Generator/Extension Cord Question

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d0gerz
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Generator/Extension Cord Question

Post by d0gerz »

I have a corded SunJoe lawn dethatcher and a 12 gauge 100 ft extension cord to run it with. The product guide says to not run it with an extension cord of longer than 100 ft. My problem is in order to fully cover the yard I need another 75 feet or so.

The machine is rated at 1560 watts. Can I run it with a 2000 Watt generator such as this Honda model? How long would it be able to power the machine for? I'd need to run the machine for an hour, maybe two hours to be on the safe side.

What other options do I have for portable power? I thought about having an electrician install a power outlet in the middle of the yard, though I imagine this would be a significant cost upfront.

Would it be a really bad idea to try and run it with two extension cords plugged together? I understand resistance increases the longer the cord length. What if I went a gauge lower for the second cord? I was thinking a 75 ft 10 gauge wire.
neilpilot
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Re: Generator/Extension Cord Question

Post by neilpilot »

For a moment let’s disregard the generator option.

You would have no problem running at 150’ using all 10 gauge, and 175’ is very likely also doable. But NOT using 100’ of 12 gauge connected to an additional 10 gauge extension.
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Sandtrap
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Re: Generator/Extension Cord Question

Post by Sandtrap »

There are charts online that will give you amp drop per distance for a “continuous” run line.
Your goal is to have minimal drop therefore larger gauge while keeping your cord practical to use.

Do not skimp on quality line and end connectors.

j🌺
Last edited by Sandtrap on Tue Sep 14, 2021 8:47 am, edited 1 time in total.
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prd1982
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Re: Generator/Extension Cord Question

Post by prd1982 »

What are the consequences of using the extension cords the OP suggested? This is for a once a year project, for a small amt of property, since he could use 1 extension cord most of the time. I’m assuming the tool might not get the full amperage requested, and the cord might get hot. Is there a danger to the person, tool or house wiring?
Laundry_Service
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Re: Generator/Extension Cord Question

Post by Laundry_Service »

I believe the Honda EU2000i is only rated to ~1300 continuous watts.
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

neilpilot wrote: Tue Sep 14, 2021 4:43 am For a moment let’s disregard the generator option.

You would have no problem running at 150’ using all 10 gauge, and 175’ is very likely also doable. But NOT using 100’ of 12 gauge connected to an additional 10 gauge extension.
Hmmm so is it that mixing two gauges is a no-no? What if I went with another 12 gauge extension for the additional 75 feet?
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

prd1982 wrote: Tue Sep 14, 2021 8:12 am What are the consequences of using the extension cords the OP suggested? This is for a once a year project, for a small amt of property, since he could use 1 extension cord most of the time. I’m assuming the tool might not get the full amperage requested, and the cord might get hot. Is there a danger to the person, tool or house wiring?
Thanks yeah you articulated it better than I could, I was wondering the same thing. It's a once a year thing for a small section of the yard. For the majority of the yard the 100 ft cord will suffice.

I'm trying to balance the cost of supplying the power as well. If I go with two 10 gauge cords, that ends up costing more than the machine itself.
hicabob
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Re: Generator/Extension Cord Question

Post by hicabob »

You can mix gauges, just do the voltage drop calculation for each cord - second cord will obviously start with less voltage than the first cord.

https://www.southwire.com/calculator-vdrop

Nice thing about it being outside is that if it gets too hot minimal damage will occur and it's easy to check. The motor could get smoked with too much voltage drop depending on the motor .
neilpilot
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Re: Generator/Extension Cord Question

Post by neilpilot »

d0gerz wrote: Tue Sep 14, 2021 8:34 am
neilpilot wrote: Tue Sep 14, 2021 4:43 am For a moment let’s disregard the generator option.

You would have no problem running at 150’ using all 10 gauge, and 175’ is very likely also doable. But NOT using 100’ of 12 gauge connected to an additional 10 gauge extension.
Hmmm so is it that mixing two gauges is a no-no? What if I went with another 12 gauge extension for the additional 75 feet?
You are missing the point. Resistance is additive. If you use that 100' run of 12 gauge, even if you extend it using 10 gauge, that 12 gauge run will still likely result in excessive total resistance.
killjoy2012
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Re: Generator/Extension Cord Question

Post by killjoy2012 »

Your best 'cheap' attempt would be to buy (2) 100' 10ga extension cords and hope it does what you need to.
You can try a 10ga + 12ga, or (2) 12ga cords, but as has been already mentioned, resistance is additive.

A generator would work, but not that Honda 2000. It's only rated for 1500W continuous, and since that dethatcher has a motor, it likely has a startup surge that would shutoff the genset.

You really need a gas-powered dethatcher. Might be better to rent one for 1/2 day from your local Rent-All store for the 1 day per year you need it.
Last edited by killjoy2012 on Tue Sep 14, 2021 7:34 pm, edited 1 time in total.
prd1982
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Re: Generator/Extension Cord Question

Post by prd1982 »

killjoy2012 wrote: Tue Sep 14, 2021 8:57 am Might be better to rent one for 1/2 day from your local Rent-All store for the 1 day per year you need it.
The problems for many, including me:

1. Not Having vehicle to transport the equipment.
2. Not having someone to help you lift the equipment in and out of the vehicle.
DoubleComma
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Re: Generator/Extension Cord Question

Post by DoubleComma »

Laundry_Service wrote: Tue Sep 14, 2021 8:17 am I believe the Honda EU2000i is only rated to ~1300 continuous watts.
At sea level EU2000I is 1600 watts continuous running and 2000i start up. More importantly it’s 13A sustained with the ability to temporarily spike to 16A for short start up bursts. We used ours regularly to run our RV all over the Western US. At high elevation we would run into challenges running high current items like a microwave.

OP - the Honda EU2000i (or newer version EU2200i) generator will run your dethatcher….unless your at elevation >7000 ft. It might get a little dicey when you Derate for power loss at elevation.
Last edited by DoubleComma on Tue Sep 14, 2021 9:27 am, edited 2 times in total.
DoubleComma
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Re: Generator/Extension Cord Question

Post by DoubleComma »

d0gerz wrote: Tue Sep 14, 2021 8:34 am
neilpilot wrote: Tue Sep 14, 2021 4:43 am For a moment let’s disregard the generator option.

You would have no problem running at 150’ using all 10 gauge, and 175’ is very likely also doable. But NOT using 100’ of 12 gauge connected to an additional 10 gauge extension.
Hmmm so is it that mixing two gauges is a no-no? What if I went with another 12 gauge extension for the additional 75 feet?
Same issue, it’s not the mixing of gauges as much as the 12 gauge can’t sustain voltage over the same span a heavier gauge can.
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Re: Generator/Extension Cord Question

Post by DoubleComma »

d0gerz wrote: Tue Sep 14, 2021 8:39 am
prd1982 wrote: Tue Sep 14, 2021 8:12 am What are the consequences of using the extension cords the OP suggested? This is for a once a year project, for a small amt of property, since he could use 1 extension cord most of the time. I’m assuming the tool might not get the full amperage requested, and the cord might get hot. Is there a danger to the person, tool or house wiring?
Thanks yeah you articulated it better than I could, I was wondering the same thing. It's a once a year thing for a small section of the yard. For the majority of the yard the 100 ft cord will suffice.

I'm trying to balance the cost of supplying the power as well. If I go with two 10 gauge cords, that ends up costing more than the machine itself.
Properly built electrical system should trip a breaker before significant danger to the person. However depending on the amperage draw of the machine you run a real risk of burning up that motor due to reduced current being available and melting of the cords and arching at the connection points.

Generally you might get away with it, but there is a real risk.

If you have a portable generator just use it and eliminate the long extension cords.
Modest Man
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Re: Generator/Extension Cord Question

Post by Modest Man »

As others have said, the generator you show is probable to small for the starting current.
You will need a longer 10 gauge cord to do the job. Or
If you can you rent a bit larger portable generator that would be more cost effective than a 10gauge cord.
Lonestar007
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Re: Generator/Extension Cord Question

Post by Lonestar007 »

DoubleComma wrote: Tue Sep 14, 2021 9:18 am
Laundry_Service wrote: Tue Sep 14, 2021 8:17 am I believe the Honda EU2000i is only rated to ~1300 continuous watts.
At sea level EU2000I is 1600 watts continuous running and 2000i start up. More importantly it’s 13A sustained with the ability to temporarily spike to 16A for short start up bursts. We used ours regularly to run our RV all over the Western US. At high elevation we would run into challenges running high current items like a microwave.

OP - the Honda EU2000i (or newer version EU2200i) generator will run your dethatcher….unless your at elevation >7000 ft. It might get a little dicey when you Derate for power loss at elevation.
Totally agree. I have a Honda EU2000 and also use on my RV as well as electric tools around the house. I feel 1600 watts continuous is possible (2000w intermittent), and if exceeded, there is a breaker on the generator that will shut it down.

By using a generator like the Honda a short heavy gauge extension cable will do the job. It would be nice if the OP could try the generator to make sure before purchase as the Hondas are pricey, but worth every penny. And by the way, if operated at higher elevations, Honda offers different carburetor orifice options.
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hand
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Re: Generator/Extension Cord Question

Post by hand »

Isn't the generator portable?

Get a shorter extension cord of lower gauge and move the generator a couple of times...
Chuck
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Re: Generator/Extension Cord Question

Post by Chuck »

IMO you are overthinking it.

200 feet of 10 gauge cord will give you less than 6% loss, and cost around $250, which is way cheaper than a generator. This would be the "by the book" solution.

I run a 12-amp electric lawn mower with 50 feet of 12, and 100 feet of 14, which is really dumb (by the book), but it has worked fine for me for years. Yes, it runs a bit slower. The cord warms up for the 20 minutes I'm using it, then I put it away. If it were continuous use, or used when no one is around, I would never do this. For short-term temporary use, I don't worry about it.
michaelingp
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Re: Generator/Extension Cord Question

Post by michaelingp »

This is a hard problem to crowd-source. The problem is nobody wants to give you the advice that results in a somewhat expensive machine burning up, or worse. You can calculate the voltage drop that the 75' of #10 extension cord + the #12 100 footer would result in (I get 113 volts), but nobody knows if the dethatcher will tolerate that and for how long. Personally, I'd just do it and feel the cords (and the connectors) to make sure they aren't unreasonably hot (I don't like more than warm myself). Most people don't know the gauge of their extension cords, so there are countless people running your machine with #14 or even #16 extension cords, which at 100' would be greater voltage drop than what you are contemplating.
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Re: Generator/Extension Cord Question

Post by Sandtrap »

We have a commercial size Honda generator and a smaller Honda 2000 portable.

We put the generator on a trailer cart behind our golf cart to do chores such as repair welding etc on our mini ranch. The generator will run a small air compressor, welding mini mig, etc.

Why not put your generator on a rolling lawn cart or equivalent and just move it around as you need with the appropriate Ext cord?

j🌺
Last edited by Sandtrap on Tue Sep 14, 2021 1:52 pm, edited 1 time in total.
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Mike Scott
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Re: Generator/Extension Cord Question

Post by Mike Scott »

Do you have a grill area or some place you would like to have a permanent power plug (and water if you are digging) within the 100' range? I would probably do the 2x100 cords and not worry about it.
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Re: Generator/Extension Cord Question

Post by AnEngineer »

DoubleComma wrote: Tue Sep 14, 2021 9:23 am Properly built electrical system should trip a breaker before significant danger to the person. However depending on the amperage draw of the machine you run a real risk of burning up that motor due to reduced current being available and melting of the cords and arching at the connection points.

Generally you might get away with it, but there is a real risk.
The only risk is to the equipment you run after the extension cord. As long as each extension cord is rated for the current used, there's no risk to the cords or your house. The only question is does the extra resistance hurt your dethatcher. Thus, I'd be hesitant when looking at solutions that cost more than the equipment. It probably has enough margin in the design to handle a longer extension cord, especially for rare short use and if it seems to act fine.

Can you just get a non-powered tool for the area in question?
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Re: Generator/Extension Cord Question

Post by suemarkp »

Also plug the extension cord into a 20A circuit (look at the breaker handle rating of the circuit you want to use). You're getting some voltage drop from the wiring in the house to the outlet. Minimize that by at least using a 20A circuit in the house which will have 12ga wire. These can usually be found in the kitchen and dining room, bathrooms, and laundry rooms. Outside circuit could be 15 or 20. Garage outlets are sometimes also 20A.

Most people who put an outlet in the yard don't upsize the wire, so that really isn't much different than using an extension cord. Even if they do, they'd probably upsize to #10 at the most. The main difference here will be extension cord wiring versus permanent, but the voltage drop in #10 copper is the same either way. My general rule for upsizing is to go up one size at 75 to 100 feet (so 14 would need to be 12). I'd upsize again around 150 to 200' (so 14 would need to be 10). I think you'll be fine with two 100' #10 extension cords.

The dethatcher will draw more than its rated current if the voltage drops too much. That can overheat it. If it is well designed, the motor will have thermal protection, shutdown if it overheats, and will resume working once it cools down. If it isn't, it will burn up and not work again. I doubt this will happen using two #10 extension cords. The tables these manufacturers give for extension cord length make no sense half the time. I think manufacturers just cut and paste them without calculating anything.
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DoubleComma
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Re: Generator/Extension Cord Question

Post by DoubleComma »

AnEngineer wrote: Tue Sep 14, 2021 2:46 pm
DoubleComma wrote: Tue Sep 14, 2021 9:23 am Properly built electrical system should trip a breaker before significant danger to the person. However depending on the amperage draw of the machine you run a real risk of burning up that motor due to reduced current being available and melting of the cords and arching at the connection points.

Generally you might get away with it, but there is a real risk.
The only risk is to the equipment you run after the extension cord. As long as each extension cord is rated for the current used, there's no risk to the cords or your house. The only question is does the extra resistance hurt your dethatcher. Thus, I'd be hesitant when looking at solutions that cost more than the equipment. It probably has enough margin in the design to handle a longer extension cord, especially for rare short use and if it seems to act fine.

Can you just get a non-powered tool for the area in question?
Based on your screen name I'm guessing your correct.

But am I wrong that as voltage drops the device will pull higher amperage which could trip the breaker. If the break doesn't trip, or say you have a 15 Amp duplex on a 20 amp circuit, you could also cook the duplex?

Very interested if my understand is wrong. I always understood a relationship between voltage and Amps to generate the required wattage existed. And since voltage drop of the cable length due to additional resistance it would cause the motor to consume excess Amperage.
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Re: Generator/Extension Cord Question

Post by AnEngineer »

DoubleComma wrote: Tue Sep 14, 2021 3:54 pm
AnEngineer wrote: Tue Sep 14, 2021 2:46 pm
DoubleComma wrote: Tue Sep 14, 2021 9:23 am Properly built electrical system should trip a breaker before significant danger to the person. However depending on the amperage draw of the machine you run a real risk of burning up that motor due to reduced current being available and melting of the cords and arching at the connection points.

Generally you might get away with it, but there is a real risk.
The only risk is to the equipment you run after the extension cord. As long as each extension cord is rated for the current used, there's no risk to the cords or your house. The only question is does the extra resistance hurt your dethatcher. Thus, I'd be hesitant when looking at solutions that cost more than the equipment. It probably has enough margin in the design to handle a longer extension cord, especially for rare short use and if it seems to act fine.

Can you just get a non-powered tool for the area in question?
Based on your screen name I'm guessing your correct.

But am I wrong that as voltage drops the device will pull higher amperage which could trip the breaker. If the break doesn't trip, or say you have a 15 Amp duplex on a 20 amp circuit, you could also cook the duplex?

Very interested if my understand is wrong. I always understood a relationship between voltage and Amps to generate the required wattage existed. And since voltage drop of the cable length due to additional resistance it would cause the motor to consume excess Amperage.
You could make a device designed to consume a set number of watts, but that could be dangerous (imagine when barely plugged in, or with little voltage, you could spike the current and start a fire). It would also be much more complicated as most things naturally respond to current (amps) or voltage. Power (watts) is generally a consequence of the other two (and current itself mostly determined by voltage). An example: in spite of what the store clerk tells you, a charger that has the correct plug, the correct voltage, and at least the required current will work for your device. You don't have to buy a charger with the "correct" current.
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Re: Generator/Extension Cord Question

Post by suemarkp »

DoubleComma wrote: Tue Sep 14, 2021 3:54 pm But am I wrong that as voltage drops the device will pull higher amperage which could trip the breaker. If the break doesn't trip, or say you have a 15 Amp duplex on a 20 amp circuit, you could also cook the duplex?

Very interested if my understand is wrong. I always understood a relationship between voltage and Amps to generate the required wattage existed. And since voltage drop of the cable length due to additional resistance it would cause the motor to consume excess Amperage.
It depends. On a space heater, as voltage drops, the current drawn also drops. So a 1500W heater is only a 1500W heater at its rated voltage. It is less watts than that under voltage drop conditions. It would also generate more heat (watts) if you plugged it into 240V. It would make so much heat the heating element would quickly burn up (happens a lot when people buy 120V baseboard heaters only to find it is a 240V circuit).

A motor is different. It does work. If the applied voltage is lower than normal, it draws more current to do the same amount of work. The problem with motors is since more current is drawn as voltage goes down under load, a voltage drop issues feeds on itself (voltage goes even lower, which increased the current, which causes more voltage drop). There are limits to this too. You don't want to put 150V on a 120V motor to help it draw less current, nor do you want to try and run it on 90V as it will most likely burn up its winding. It also depends on the motor type. A universal motor will spin faster on higher voltage and slower on less. Induction motor speed is determined by voltage frequency. The RPM affects the work being performed.

Both 15A and 20A duplex receptacles are the same internally (metal thickness and width). They will each take a 20A load. The only difference is the T slot on the 20A version. A 15A receptacle is supposed to be limited to 15A, and that is generally enforced by the device (it doesn't get a 15A plug if the nameplate amps is over 15, UL determines how you calculate the nameplate amps).
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michaelingp
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Re: Generator/Extension Cord Question

Post by michaelingp »

DoubleComma wrote: Tue Sep 14, 2021 3:54 pm But am I wrong that as voltage drops the device will pull higher amperage which could trip the breaker. If the break doesn't trip, or say you have a 15 Amp duplex on a 20 amp circuit, you could also cook the duplex?
You are correct some types of motors will draw more amps if the voltage drops. (Resistive loads will draw less.) However since 15 amp receptacles are permitted on 20 amp circuits (and that's what most electricians install), I'm assuming the folks that write the code figure that 15 amp receptacles can in fact can carry 20 amps. The only reason, then, for 20 amp receptacles is for 20 amp plugs which are pretty rare. Also, I think you can assume a 15 amp breaker will trip at pretty close to 15 amps.
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Re: Generator/Extension Cord Question

Post by forkhorn »

The worst thing that will happen is you damage the power tool. In your case I'd say it's unlikely. You can spend a lot on heavy extension cords or just do it and you'll probably be fine. If it were me, I'd do it without hesitation. In fact, I do have a 14.5 amp electric chainsaw that I run all the time through two 100' 12ga cords without issue.

One comment though, which I didn't see asked above. If you're using a generator, just wheel the generator around and only use one cord. Why not just move the generator once or twice mid-job? Why daisy chain cords to reach a very portable generator?
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Re: Generator/Extension Cord Question

Post by CurlyDave »

d0gerz wrote: Mon Sep 13, 2021 11:18 pm
...The machine is rated at 1560 watts. Can I run it with a 2000 Watt generator such as this Honda model? How long would it be able to power the machine for? I'd need to run the machine for an hour, maybe two hours to be on the safe side...
You do not need a Honda-quality generator for very occasional use. Go down to the closest Harbor Freight and they will sell you an adequate generator for a couple hundred $.
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Re: Generator/Extension Cord Question

Post by snackdog »

Why not just trade your corded dethatcher for a cordless one for under $200?

https://www.amazon.com/SuperHandy-Scari ... den&sr=1-2
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Re: Generator/Extension Cord Question

Post by willthrill81 »

Chuck wrote: Tue Sep 14, 2021 11:24 am IMO you are overthinking it.

200 feet of 10 gauge cord will give you less than 6% loss, and cost around $250, which is way cheaper than a generator. This would be the "by the book" solution.

I run a 12-amp electric lawn mower with 50 feet of 12, and 100 feet of 14, which is really dumb (by the book), but it has worked fine for me for years. Yes, it runs a bit slower. The cord warms up for the 20 minutes I'm using it, then I put it away. If it were continuous use, or used when no one is around, I would never do this. For short-term temporary use, I don't worry about it.
I agree. The only problem here is that the voltage may drop a bit, but as long as the voltage at the outlet is good (at least 120v, which it should be), even a 10% drop to the dethatcher would still be within normal parameters. A dethatcher definitely does not qualify as an electronically sensitive piece of equipment.

For years, I ran a 1,200 watt lawn mower with a cheap 16 gauge 100' extension cord with zero problems.
“Good and ill have not changed since yesteryear; nor are they one thing among Elves and Dwarves and another among Men.” J.R.R. Tolkien, The Lord of the Rings
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Re: Generator/Extension Cord Question

Post by willthrill81 »

CurlyDave wrote: Wed Sep 15, 2021 9:37 am
d0gerz wrote: Mon Sep 13, 2021 11:18 pm
...The machine is rated at 1560 watts. Can I run it with a 2000 Watt generator such as this Honda model? How long would it be able to power the machine for? I'd need to run the machine for an hour, maybe two hours to be on the safe side...
You do not need a Honda-quality generator for very occasional use. Go down to the closest Harbor Freight and they will sell you an adequate generator for a couple hundred $.
Yes, the Predator brand of generators they sell are remarkably good in quality. Their inverter generators are quite common in the RV community. For occasional use, there is no need to spend the premium on a Honda or Yamaha (said by someone who's owned a Yamaha inverter generator for the last 7 years without issue).
“Good and ill have not changed since yesteryear; nor are they one thing among Elves and Dwarves and another among Men.” J.R.R. Tolkien, The Lord of the Rings
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

forkhorn wrote: Tue Sep 14, 2021 9:21 pm The worst thing that will happen is you damage the power tool. In your case I'd say it's unlikely. You can spend a lot on heavy extension cords or just do it and you'll probably be fine. If it were me, I'd do it without hesitation. In fact, I do have a 14.5 amp electric chainsaw that I run all the time through two 100' 12ga cords without issue.

One comment though, which I didn't see asked above. If you're using a generator, just wheel the generator around and only use one cord. Why not just move the generator once or twice mid-job? Why daisy chain cords to reach a very portable generator?
Yeah I was thinking in terms of either/or, not both get a generator AND multiple extension cords. I'd prefer a generator but they seem pricy. The link upthread was for a Home Depot rental but sounds like the jury's out as to whether it'll be powerful enough.
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

michaelingp wrote: Tue Sep 14, 2021 1:47 pm This is a hard problem to crowd-source. The problem is nobody wants to give you the advice that results in a somewhat expensive machine burning up, or worse. You can calculate the voltage drop that the 75' of #10 extension cord + the #12 100 footer would result in (I get 113 volts), but nobody knows if the dethatcher will tolerate that and for how long. Personally, I'd just do it and feel the cords (and the connectors) to make sure they aren't unreasonably hot (I don't like more than warm myself). Most people don't know the gauge of their extension cords, so there are countless people running your machine with #14 or even #16 extension cords, which at 100' would be greater voltage drop than what you are contemplating.
Do you mind sharing how you calculated the voltage drop to 113 volts? There were a couple of links posted here to calculators but tbh I was a little bewildered by the choices and not understanding technical terms (power factor, phases, number of conductors etc?)
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Re: Generator/Extension Cord Question

Post by suemarkp »

Voltage drop is resistance * amps going through it. A 100' cord has 200' of electricity travel (it goes to the plug and back). Resistance for wires sizes is approximately as follows:

#14 stranded = 0.32 ohms per 100'
#12 stranded = 0.2 ohms per 100'
#10 stranded = 0.125 ohms per 100'

Assuming each cord is 100', that requires 200' of the resistance value for each cord. So resistance is 0.4 + 0.25 = 0.65 ohms if one cord is #12 and one cord is #10. Current was 13 amps. So 13 * .65 = 8.45V lost.

There will be additional voltage drop between the power panel and the wall outlet being used. But, house voltage supplies are usually more than 120V and less than 125V. So assuming 120V at the outlet is a good approximation. The motor should work fine down to 110V. So having a 10V drop in the cord should be acceptable.
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

suemarkp wrote: Wed Sep 15, 2021 1:30 pm Voltage drop is resistance * amps going through it. A 100' cord has 200' of electricity travel (it goes to the plug and back). Resistance for wires sizes is approximately as follows:

#14 stranded = 0.32 ohms per 100'
#12 stranded = 0.2 ohms per 100'
#10 stranded = 0.125 ohms per 100'

Assuming each cord is 100', that requires 200' of the resistance value for each cord. So resistance is 0.4 + 0.25 = 0.65 ohms if one cord is #12 and one cord is #10. Current was 13 amps. So 13 * .65 = 8.45V lost.

There will be additional voltage drop between the power panel and the wall outlet being used. But, house voltage supplies are usually more than 120V and less than 125V. So assuming 120V at the outlet is a good approximation. The motor should work fine down to 110V. So having a 10V drop in the cord should be acceptable.
Thank you!
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Re: Generator/Extension Cord Question

Post by iamlucky13 »

TLDR summary: use one of the extension cord combos I list below, and go a bit slower than normal to be ensure a long life from the tool.

Reported generator experiences for powering electric tools vary, but I have seen Honda EU2000 users on other sites report being able to power other tools with similar ratings (12-13A), such as circular saws and electric chainsaws. I have also seen some report they aren't able to provide enough power for the initial inrush.

So it appears marginal, and it's hard to say how well it would work without actually trying a specific tool with a specific generator.
d0gerz wrote: Tue Sep 14, 2021 8:34 amHmmm so is it that mixing two gauges is a no-no? What if I went with another 12 gauge extension for the additional 75 feet?
The concern here is not specific gauges and lengths, but sufficient voltage reaching the tool. If the voltage drops too much, the motor slows more under load than intended. At lower speeds, efficiency declines, producing more heat, and current draw can actually increase compared to normal speeds, meaning even more heat. Taken too far, the motor will burn out. Manufacturer listed requirements tend to be fairly conservative, but on the other hand, you can burn out a motor even if it is receiving adequate power if you bog it down too much.

I'll put some numbers to this, assuming this is your dethatcher, or a close equivalent. The actual instruction I see is 50' of 16 AWG or 100' of 14 AWG:
https://snowjoe.com/products/sun-joe-13 ... ection-bag

The worse of the two conditions above is 100' of 14 AWG, which per an online calculator provided by a cable manufacturer should result in 7.5V drop at 12A. Here's a couple alternate voltage drops:

100' of 10 AWG + 100' of 12 AWG = 7.7V
100' of 10 AWG + 75' of 12 AWG = 6.6V
75' of 10 AWG + 100' of 12 AWG = 6.9V

So there's the numbers for you. No generator needed. You might be surprised to see how much a 100 foot, 10 gauge extension cord costs, however.

One of those configurations is just slightly more voltage drop than the manufacturer specified extension cord, but it's probably close enough. First of all, the power you're receiving at your house probably is not at the minimum voltage tolerance. Second, you can slow down to reduce the load on your dethatcher - you have exactly the right instinct when you suggested giving yourself 2 hours to do the job instead of trying to finish in an hour.

Disclaimer: I feel like I should also mention that the above is not in accordance with the listed use of either the dethatcher or the extension cords (which are not intended to be chained). Those listed uses are in part too keep people not able to quantify the effects as above as not creating a hazard, so I personally see no issue with those who can quantify the effects evaluating equivalent alternatives. However, I'm bringing this up for full disclosure, and because OSHA regulations would prohibit doing this in a workplace (they don't apply to personal use). I have personally done similar at my home and would do so again. I would not ask a coworker to do it.

You could also consider one of the newer cordless dethatcher's, although it sounds like you have a large yard, and it would probably take several battery charges. It's hard to estimate how many charges, not knowing how much power a dethatcher really consumes. It is not actually 1560W continuous. A KillaWatt is a handy tool for determining actual consumption. I see Home Depot showing (although out of stock right now) a Greenworks 40V model for $300 with one 4 AH battery, with "up to 30 minutes runtime." That's an average power draw of about 300W. Extra batteries are really expensive, but still a lot cheaper than an EU2000i.

Or if you really want to avoid any scenario not specified by the manufacturer, you can just use a rake for any areas your power dethatcher can't reach.
snackdog wrote: Wed Sep 15, 2021 9:43 am Why not just trade your corded dethatcher for a cordless one for under $200?

https://www.amazon.com/SuperHandy-Scari ... den&sr=1-2
That model is half the battery capacity of the one I mentioned, and I have reservations about the capacity even of the one I mentioned.
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

Thanks all for your replies. Yeah I may be overthinking this but I really want to get this project started/done and was having choice paralysis. Seems like my options are:

1) Rent/buy a generator rated for more than the running watts + some starting surge rating. Per Sun Joe their running/starting wattage is the same for this unit i.e. 1560 watts.
2) Get 2 10 gauge 100' wires or 1 100' and 1 75'
3) Roll the dice with mixing 10 gauge with the 12 gauge I already have and hope the motor doesn't burn out
4) Rent a dethatcher but for that I would also have to rent a truck for transport or borrow a friend's car and labor etc
5) Cover whatever 100' will get me and leave it at that, or use a regular thatching rake for the rest and do it manually
6) Get battery powered dethatcher. I have looked into this but for the models out there I don't think the batteries are going to last long enough to be able to do it in a single or even two or three sittings. So a lot of waiting around for batteries to charge or buying lots of spare batteries.
7) Hire it out. But I like doing my own yard maintenance
8) Do nothing it is just a yard after all lol

I'm leaning 3. Will report back. Though also checking Craigslist to see if someone's offloading a generator. New ones seem too expensive, even HF models are $400+
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Re: Generator/Extension Cord Question

Post by Mike Scott »

I vote for #8.
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Re: Generator/Extension Cord Question

Post by neilpilot »

or option #9 - continue to overthink until the seasons change and the job can't be done
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TexasPE
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Re: Generator/Extension Cord Question

Post by TexasPE »

Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
At 20: I cared what everyone thought about me | At 40: I didn't give a damn what anyone thought of me | Now that I'm 60: I realize that no one was really thinking about me at all | Winston Churchill (?)
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willthrill81
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Re: Generator/Extension Cord Question

Post by willthrill81 »

TexasPE wrote: Wed Sep 15, 2021 2:38 pm Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
That would be my vote. It would be far cheaper than a 100' 10 gauge cord, which would be around $120.
“Good and ill have not changed since yesteryear; nor are they one thing among Elves and Dwarves and another among Men.” J.R.R. Tolkien, The Lord of the Rings
iamlucky13
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Re: Generator/Extension Cord Question

Post by iamlucky13 »

suemarkp wrote: Wed Sep 15, 2021 1:30 pmThere will be additional voltage drop between the power panel and the wall outlet being used. But, house voltage supplies are usually more than 120V and less than 125V. So assuming 120V at the outlet is a good approximation. The motor should work fine down to 110V. So having a 10V drop in the cord should be acceptable.
The voltage drop to the outlet applies regardless of what extension cord the user has

The manufacturer had to design for the utility providing 120V +/- 5% (ANSI C84.1), meaning a minimum of 114V at the home's meter. National Electric Code prescriptions for building wiring generally limit the drop within a building to another 6%.

In other words, electrical equipment manufacturers should be designing their 120VAC products to operate acceptably at as little as 106.8V (in some material I actually 104.4V mentioned, but I'm not sure where that comes from).

Since the dethatcher manufacturer specified a 100' extension cord, they should then assume additional voltage drop in the cord.
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

willthrill81 wrote: Wed Sep 15, 2021 2:55 pm
TexasPE wrote: Wed Sep 15, 2021 2:38 pm Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
That would be my vote. It would be far cheaper than a 100' 10 gauge cord, which would be around $120.
Yeah except I don't have an SUV. Maybe I should buy one just for this project :mrgreen:
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willthrill81
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Re: Generator/Extension Cord Question

Post by willthrill81 »

d0gerz wrote: Wed Sep 15, 2021 2:58 pm
willthrill81 wrote: Wed Sep 15, 2021 2:55 pm
TexasPE wrote: Wed Sep 15, 2021 2:38 pm Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
That would be my vote. It would be far cheaper than a 100' 10 gauge cord, which would be around $120.
Yeah except I don't have an SUV. Maybe I should buy one just for this project :mrgreen:
I think that Home Depot will let you rent a truck starting at $19 plus mileage.
“Good and ill have not changed since yesteryear; nor are they one thing among Elves and Dwarves and another among Men.” J.R.R. Tolkien, The Lord of the Rings
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

Mike Scott wrote: Wed Sep 15, 2021 2:19 pm I vote for #8.
neilpilot wrote: Wed Sep 15, 2021 2:25 pm or option #9 - continue to overthink until the seasons change and the job can't be done
:sharebeer
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d0gerz
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Re: Generator/Extension Cord Question

Post by d0gerz »

willthrill81 wrote: Wed Sep 15, 2021 2:58 pm
d0gerz wrote: Wed Sep 15, 2021 2:58 pm
willthrill81 wrote: Wed Sep 15, 2021 2:55 pm
TexasPE wrote: Wed Sep 15, 2021 2:38 pm Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
That would be my vote. It would be far cheaper than a 100' 10 gauge cord, which would be around $120.
Yeah except I don't have an SUV. Maybe I should buy one just for this project :mrgreen:
I think that Home Depot will let you rent a truck starting at $19 plus mileage.
For 75 minutes*. This job will take me a lot longer so I'll probably need a U-Haul or some such.

*The last time I did that they started the clock as soon as I finished signing the paperwork as opposed to when I got in the truck, which was 15 minutes later.
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Re: Generator/Extension Cord Question

Post by TexasPE »

d0gerz wrote: Wed Sep 15, 2021 2:58 pm
willthrill81 wrote: Wed Sep 15, 2021 2:55 pm
TexasPE wrote: Wed Sep 15, 2021 2:38 pm Rent something like this gasoline powered model...

https://www.homedepot.com/p/rental/Clas ... /301609427

$44 for 4 hours. Should fit in an SUV cargo area.
That would be my vote. It would be far cheaper than a 100' 10 gauge cord, which would be around $120.
Yeah except I don't have an SUV. Maybe I should buy one just for this project :mrgreen:
Responses like this make me GLAD I wasted the time to do a little research...
At 20: I cared what everyone thought about me | At 40: I didn't give a damn what anyone thought of me | Now that I'm 60: I realize that no one was really thinking about me at all | Winston Churchill (?)
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