# Detached Garage Sub Panel



## MainePainter (Aug 24, 2006)

After reading eveything I could and talking to those more knowledgeable than I, I think that I have all my bases covered, but I would appreciate any input or red flags from cyberspace.

My plan is to install a new 100Amp main panel in my detached garage located 15ft from the house and approximately 50ft from the main service panel. I intend to run 2 8guage hot leads and 1 neutral lead from a 50Amp breaker in the house to 100amp breaker and the neutral lug in the new sub panel. I also will run an 8 guage ground wire between the two panels. All wires will run inside a PVC conduit buried 18" below ground in a trench. Further, an 8' copper grounding rod will be driven into the ground and connected to the sub panel via a 6guage copper wire. The new panel will power a 20Amp 240V space heater, plus circuits for lights and outlets.

I have two questions: 1) Does the grounding rod wire get connected to the neutral bus bar or the equipment ground bus bar in the sub panel; and 2) What is the purpose of the bonding screw and should I install it?

Thanks in advance for your help.


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## jwhite (Mar 12, 2006)

You can use a number 10 ground wire.

Do not use the bonding screw. Depending on the make of the panel. the two bars may be on each side of the breakers and tied together with a cross bar. With this type panel you can remove the cross bar and use one side for your grounds. The ground wire from the rod goes to the ground bar. The ground bar should also be bonded to the panel enclosure. If you go to an electrical supply house and tell them that you want to use that panel as a sub panel, they will sell you all the right stuff.


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## darren (Nov 25, 2005)

MainePainter said:


> I intend to run 2 8guage hot leads and 1 neutral lead from a 50Amp breaker in the house to 100amp breaker and the neutral lug in the new sub panel.


Why are you running only a 50A breaker from the house, this will only get you a 50A panel in your shed. To what you say your wiring you will be fine but just curious why you wouldn't run it to a 100, or maybe your trying to save yourself a few bucks which would make sense.


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## stagger19 (Mar 12, 2006)

Im doing the same thing in my garage that I just built. Im running 6 ga wire out to the 100 amp sub panel, but my over current protection in the main panel will only be a 50 amp breaker.

In the sub panel, I will have (1) 20 amp branch circuit for my receptacles, and (1) 15 amp circuit for my shop lights. The other 15 amps is for a future breaker that will connect the garage door opener, and an exhaught fan in the rear gable.

*** Just make sure you run THWN thru the PVC. The pipe will fill with water from condesation over time, and normal Romex (NM) cable is not rated for wet application. Other option is running UF (underground Feeder) which is rated for direct burial.

Im coming off my main breaker panel in my basement with 6-3G romex into a Junction box where i will Splice over to the THWN and piped Into the sub panel.


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## MainePainter (Aug 24, 2006)

My reasoning for a 50A breaker was simply that with only 100A service to the house and the needs that I stated earlier, it seemed like overkill to push any more power than necessary.

By the way, can someone explain exactly what the purpose of the bonding screw is? I like to learn as much about stuff as I can


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## jwhite (Mar 12, 2006)

The bonding screw bonds the panel enclosure itself, and any ground bar that is mounted to the back of the can is grounded then through the can. This is so that if any of the wires in the panel short to the panel enclosure, or can, the breaker will trip.

Don't confuse the bonding screw with the neutral to ground bond bar, or wire that should be installed in a main panel and not installed in a sub panel. Even in a sub panel the ground bar should be bonded in some way to the can. If it is mounted to the can itself using drilled and tapped holes and machine screws this counts. If it was on insulators and a bond bar between the ground and neutral was removed, then the ground bar still needs to be bonded to the can.


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## jwhite (Mar 12, 2006)

Just a little more electric speak.

A panel is an assembly of electrical components like buss bars, lugs, and breakers.

An enclosure or can is the box that a panel goes in.


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