Subpanel Questions

[gpalmer77]

Getting ready to do some real electrical work, and want to make sure I'm on the right track. I've done research to get to this point, so thank you already for a lot of information I've gathered from other threads.

Looking to take a 60A service to my detached garage, from a 100A panel in the house. Running #6 copper for two hots and the common, but unsure of size needed for the ground back to the main panel. I have 1 1/4" pvc underground, with EMT in the house for the run from the main panel to the underground transition. Using THWN wire, total run is 80 of 90 ft.

I have a 100A subpanel that someone gifted me, can I change out the main breaker in this to a 60A so it matches the rating of the one in the main panel? It is a Square D Homeline panel, I want to use the actual panel because it has a lot of space in it, and it is already mounted with a lot of conduit run already. I have a separate ground bar from the common bar, common is not bonded to the ground. Planning 2 10' ground rods for the garage.

Am I doing this right, and can anyone answer the couple of questions I have?

Thanks,

Gavin.

 

[gpalmer77]

Some research this afternoon says I can keep the 100A breaker in the garage panel, by code it is merely a disconnect. The overcurrent protection is the 60A breaker in the main panel. It would be misleading to a fresh set of eyes, suggesting 100A service is present, but apparently not a code violation so long as the wire size is compatible with the lugs.

 

[pattenp]

You're fine with the 60A feed to a 100A sub. The ground needs to be no smaller than #10 for 60A circuit. Make sure you run the correct type wire for wet locations (conduit underground).

 

[gpalmer77]

Scouting mission to Home Depot at lunchtime showed that the 6awg Cerrowire is THHN/THWN rated. $65 for a 100ft spool.

 

[pattenp]

I now realize you said THWN in the OP, so you're good. I assume you know to use #6 Cu for connecting the ground rods to the sub-panel and the wire needs to be one continuous piece. Rods also need to be at least 6ft apart from each other.

 

[Aceman]

Adding to pattenp's post, the rods only need to 5/8" x 8' long.

Also, the #6 neutral wire MUST have white insulation. You cannot buy a big spool of black and simply use white tape for the neutral wire. #4 and larger can be taped, however.

 

[teamextreme]

Some research this afternoon says I can keep the 100A breaker in the garage panel, by code it is merely a disconnect.

Correct. Of course the home inspector my dad had to deal with when he sold his place didn't know this and wrote that up as a violation for the subpanel I installed in his shop. Dad had to hire an electrician to come out and basically write up a ticket that said it, and everything else, was to code.

 

[gpalmer77]

All helpful information. Thank you guys.

 

[justind]

I just did the same exact thing, 60 amp from the house to a 100 amp panel in the garage about 100 foot of wire box to box. I used #6 hots and neutral and a #8 ground (has to be green). When I asked my electrical supply house for white neutral wire they told me they just stock black and then green for the ground when selling it by the foot which I think was 49 cents a foot for number 6.

I coded the neutral with white tape and one of the hots with red I passed rough in a couple weeks ago.

As said you need 2 5/8 by 8' ground rods 6 feet apart with a continuous number 6 ground wire. I used a 25 footer or solid bare copper from home depot for 20 bucks rods are 9 each and the clamps are a few bucks each.

Also in case you did not know the 110v outlets have to be tamper resistant and gfci protected.

 

[Norcal]

I just did the same exact thing, 60 amp from the house to a 100 amp panel in the garage about 100 foot of wire box to box. I used #6 hots and neutral and a #8 ground (has to be green). When I asked my electrical supply house for white neutral wire they told me they just stock black and then green for the ground when selling it by the foot which I think was 49 cents a foot for number 6.

I coded the neutral with white tape and one of the hots with red I passed rough in a couple weeks ago.

As said you need 2 5/8 by 8' ground rods 6 feet apart with a continuous number 6 ground wire. I used a 25 footer or solid bare copper from home depot for 20 bucks rods are 9 each and the clamps are a few bucks each.

Also in case you did not know the 110v outlets have to be tamper resistant and gfci protected.

You cannot use tape for 6 AWG & smaller conductors, HD does sell it by the foot.