Friend installing a subpanel for me. Need to know what to buy. 250 feet from house. 4 wire all aluminum #2 in conduit under ground.Not hooked up at barn or house yet. Just cable ends ready to go.
Was given a 100 amp square D 6 spaces box. DO I need a main shut off in the barn? Will this box work? Can I put ground rods in the barn. I have rubber matts in this room I can cut out piece a drive rods in instead of going outside? 2 rods 6 feet apart? I will be having installed 4 2 tube fluorescent lights on one circuit with a plug in on one end with on off switch for possible small dusk to dawn light add on later. Also second branch will have 2 lamp fixture in feed room with plug in for accessories like electric shears. Nothing more than 1,500 watts at high end.

I have 60/60 breaker, two 20 amp, two 15 amp. 100 amp box does not have ground bar kit.

Any one want to help a real electrical dummy

My answers follow your questions:

DO I need a main shut off in the barn?

A main in the subpanel is not needed, but one can be here if desired for convenience.

Will this box work?
It should work, and model number would be helpful to be sure. If the panel does not come with a main breaker kit and is added in a branch circuit slot, a main breaker retainer kit is needed.


Can I put ground rods in the barn.

Yes, a ground rod(s) are needed for a subpanel in a separate building with a four wire feeder.

100 amp box does not have ground bar kit.

You will need a separate equipment ground bar kit to mount into the panel, bolted directly to the panel with machine thread screws, and connect only green and bare ground wires, and any wire to ground rods.

Leave the neutral bar insulated and isolated and only use for insulated neutral wires.


2 rods 6 feet apart?
Yes, at least 6 feet apart if more than one rod is used.



Since this will be for livestock, you may need an Equipotential Ground Plane, which is a fancy name for connecting all metal in the livestock area to a common ground connection to protect livestock from stray voltages:

http://www.egr.msu.edu/age/extension...Facilities.pdf

http://www.mrec.org/pubs/2006%20MREC...l%20Planes.pdf

I do not believe this will be a sub panel since the structure is detached. I would wire as a main panel, You only have 6 spaces so the move of the hand rule will be OK. You will need a 8 foot driven rod and if any metal water lines are present they will also need to be in the ground circuit. Do not forget the GFCI's for your protection and especially when using your electric tools. Make sure you get a neutral bonding screw also. All else will be standard wiring practices as outlined in the NEC.

NOTE if this is a metal barn bond it to the panel. I would also put the G rod outside this is just my preference.

Hey tkrussell does he really have to wire this as a sub??

The only difference is the Main, since there will be a breaker at the source, or main panel on the property, protecting the feeder and the new panel, a Main is not needed at this panel.

Good catch on the "Six Switch Rule", but let's not confuse a DIY'er, too much.

Why waste two breaker slots on a Main Breaker.

A ground rod driven inside or outside is only a preference, it is still driven into earth 8 feet, and no longer inside or outside.