Neutral/ground size for 4AWG 220VAC ?

[bcarwell]

I am running a 100 amp 220VAC service buried in conduit to my shed. The online wire calculators you all kindly provided indicates 4AWG copper wire. But nowhere can I find what size to use for the neutral and the ground wires.
Could somebody tell me as a double check to whatever the guy at Home Depot is going to say ? I also checked in the Ugly book tables but am not sure of those either.
And not to worry. Work will be permitted and I'll have licensed electrician signing off. I just want to get started today with purchases.
And any clever tips on pulling these through 125 feet of conduit ? I saw somewhere about using a shopvac and grease, etc., but it sure seems just using a length of string and a washer would do fine, no ?

Thanks for any info and Happy New Year to all,

Farmer Bob

 

[Farwell]

Bob,
For the 125 foot run using copper wire I would use #2 copper for the two hot legs, #2 copper for the neutral and at least a #6 for the ground. Not sure what your amp load will be at your destination. I would consult your electrician prior to purchasing your wire to make sure on the wire size and I would also do some serious shopping for the wire because it can vary a lot between suppliers.
See my post on pulling the wire.
Be prepared for some heated discussion because almost every time anything associated with wiring is posted the fir starts flying. Best advice is to consult your licensed electrician.
David B

 

[caver]

Yeah, run #2,,,Neutral too. You can run a # 8 for your grounding electrode. Local/newer codes could be more strict.
You can vacuum something light and almost the diameter of the pipe tied to a lightweight string. This will be your mouse. They actually make a professional version of what I'm talking about. An electrical supply house may have spares in stock. Then use the string to pull in a rope. While at the supply house pick up some wire lube
Dump a handful of this into the pipe you are feeding the wire into. Have someone help feed this wire in while generously smearing it on the conductors.
I've used dish soap in a pinch but the wire lube is much better. Don't use grease.
I also forgot that there is also a mouse/string unit listed here.
Powr-Fish®, Pull Line, Pro-Pull Rope, Foam Carriers & Line Packages, Conduit Measuring Tape

 

[Farwell]

Yeah, run #2.
You can vacuum something light and almost the diameter of the pipe tied to a lightweight string. This will be your mouse. They actually make a professional version of what I'm talking about. An electrical supply house may have spares in stock. Then use the string to pull in a rope. While at the supply house pick up some wire lube
Dump a handful of this into the pipe you are feeding the wire into. Have someone help feed this wire in while generously smearing it on the conductors.
I've used dish soap in a pinch but the wire lube is much better. Don't use grease.
I also forgot that there is also a mouse/string unit listed here.
Powr-Fish®, Pull Line, Pro-Pull Rope, Foam Carriers & Line Packages, Conduit Measuring Tape

Caver,
I went to the site you posted on pulling mice. I noticed that the last set of wires I pulled that there was quite a bit of moisture in the underground conduit. I guess that the moisture came from condensation due to the underground conduit was cold and the outside air temperature was in the 80s.
I did not know that the commercial mice would help remove the moisture. Thanks for the information. I learned something new.
On using petroleum based grease as a pulling lube, petroleum can soften some rubber and plastic products. I agree that in a pinch, liquid dish soap is a much better idea.
David B

 

[SPIKER]

the ground only needs to be a #8.

You did not state if you are running a NEW service or running from you current service as a Sub-Panel in he shed. Either way you HAVE to put in a ground rod for the other building and tie the GROUND rod to the Ground of the new building service panel.
this means you do not need to run a ground wire from the old building to the NEW building unless you're local codes differ from NEC. Only have to run 2 hots and one Neutral wire in this case...

BUT if you are running to a different building and powering this shed from you're HOME service. then you need the new ground rod, you don't need the ground wire from old service. You must not bond the new service ground to the new building Neutral (the Neutral must not have ground wires attached and vice versa.) the New Service Panel gets bonded to the NEW ground rod using #8 unsheilded conductor. (stranded is better as it is easier to work with but they also have solid #8 for same use.)

hope this helps.

 

[kmdigital]

When running to my barn from the existing house service panel, I used a 4 conductor aluminum service entrance cable, even though it was inside of a 2" conduit. This way it made it much easier inside the house, because I didn't need conduit in the basement as essentially I was running large romex wire to the main panel. Use copper if you want, but aluminum is much cheaper, and very seldom do you actually use more than 30 or 40 amps max on a 100 amp service.

By buying a service entrance cable all the conductors are already bundled inside an outer covering and properly sized for you. You can get this in either direct burial underground cable, or in cable designed for above ground use, such as to a mast head, etc. It is cheaper than buying the separate conductors, and it was cheaper at the electrical supply house than at Lowes or Menards.

Aluminum is always used by the utility companies around here for all services, so I figured it was more than adequate for my needs. Just coat the connections with a good antioxidant grease before tightening the screws, although the utility companies don't even bother to do that.