I’m trying to install one temporary GFCI outlet about 200′ away from my main house service panel to plug 120v power tools into.
I have checked voltage drop calculators and it seems as though I can use a 10ga wire if it is 240v, 3 wire setup with a 5% max drop
My plan is to run this 10-3 wire to an outdoor subpanel and then install one single pole 20 amp circuit breaker in the box going to the GFCI outlet.
The problem is the subpanel has 2 lugs for the power supply and then another for the neutral. If I attach the black and red wires to seperate lugs and just use a single pole breaker, I will still have the voltage drop problem that the 10-3 wire was supposed to solve won’t I? Can I put the two hot wires under the one lug that the single pole breaker is touching. This sounds wrong to me, but I can’t think of how to convert this 240v back to 120v in order to use a standard GFCI outlet while keeping the voltage drop at acceptable levels.
I hope this makes sense. My understanding of electricity is pretty limited, so I may be missing something obvious.
Any help would be greatly appreciated
GregS
Replies
GregS,
Please, your post has so many errors that it is obvious that you do not have enough education about electricity and home wiring to do this yourself. Hire an electrician.
As an alternative, go buy 2 "Contractor Grade" (hehehe) 100' 20amp extension cords and see if that will power your tools. You might need a Pigtail to convert from 20a to 15a plugs.
What tools? what are their draws?
SamT
I most profoundly agree.
GregS - Please don't take this personally or as any form of insult. Failing to get this absolutely right, close enough won't get it, could get you, or someone you care about, hurt.
A short visit from a trained electrician, the local handyman might not be a good choice, is cheap compared to a trip to the ER or a funeral.
The voltage drop on a 10ga wire will be dependent on the amperage being used, regardless of the voltage.
Typically a 240v circuit is run if there will be more than one device using the circuit. That is, you might have a Skilsaw on the black side and a table saw on the red side, both working at once. With this arrangement you actually get LESS voltage drop at the tools when both are running vs what you would have with only one running.
But if you're going to be working single-handed, you'll only be using one device at a time, and it's pointless to have a 240v circuit. You might as well just build a glorified 120v extension cord (or buy one), using 10-2wg.
Thanks for your input. Unfortunately what you are saying is exactly the opposite of what I based my temp power pole on. I was looking at this website http://www.stanselectric.com/vdrop.html
Besides having the voltage drop calculator, it says "An interesting corollary is that if the line voltage doubles (240 instead of 120volts) the voltage drop decreases by a factor of 4. That means that a line can carry the same power 4 times further! Higher voltage lines are more efficient. "
This is why I went with a 10-3 wire with 30 amp breaker at the service.
Actually, probably much to the dismay of the other people that answered this post, I went ahead and wired it this way, keeping the two hot wires under their respective lugs in the subpanel. Then took the GFCI off a 20 amp single pole breaker. It worked, but I still don't know if I am getting the benefit of the 240v as you pointed out.
According to the website though, the voltage drop on a 10-2 wire at 200' is to high to risk.
That site's "interesting corollary" is not very well explained. IF POWER REMAINS CONSTANT, doubling the voltage allows distances four times as long with the same wire gauge.
For instance, if you RE-WIRE a submersible pump or an air compressor to run on 240 volts, then you will get less voltage drop. 1/2 the voltage drop because it pulls 1/2 the amps. And the % voltage drop will be reduced by 1/2 again because you are dividing by a bigger number.
But you can't rewire your skillsaw, etc. Unless you go to Europe, Japan, or the Middle east and buy a 240-volt unit.
What you did (red and black carrying the same phase and white the carrying the return current) reduces the voltage drop to 3/4 of what it would have been (if you had used black going out and white coming back).
I've done stuff like that, but only when I'm the only when using the non-standard set-up and I always disassembly it before I leave.David Thomas Overlooking Cook Inlet in Kenai, Alaska