Sub panel wiring?

[ELMO67]

I have just added an attached garage, and now need to add electricity to it. I have a 125 amp subpanel mounted in the basement of the garage, it is approximately 40-45 feet from the main panel. My question is - what size cable do I need to run from panel to panel. I'd prefer to use copper, and does the subpanel need it's own ground cable/ ground rod? I hope this was the correct forum to post this question to ,I apologize if it isn't.

 

[WVBill]

Is the garange a detached building or in the same building as the main panel?

 

[Inspector507]

Attached garage does not need a ground rod, but yes needs a grounding conductor from the main panel. Decide if you want 125A, 100A, 90A....then make your wire selection . (We'll help) /forums/images/graemlins/grin.gif

 

[ELMO67]

Thanks for the replies, so far! The garage is attached to the house by way of a 10'x 12' mudroom. The house, mudroom and garage all have basements, which is where the main panel ( house), and subpanel (garage) are located. The subpanel I have mounted in the garage basement is rated at 125 amp capacity; I would like to have that full capacity available. I think that the most I'll be drawing at one time would be 60 amps, but that may not allow for a start up draw.

 

[TWINKLE_TOES]

<font color="blue"> (We'll help) </font>

You just did /forums/images/graemlins/smile.gif I have had the ground rod on my to-do list for 5 years. Amazing how time solves problems, thanks

 

[Inspector507]

For 125A feed to the garage, you’ll need to keep the following in mind.
Assuming all your terminations are rated at 75°C, you can use #2AWG Cu to feed the sub-panel. The #2 is rated at 115A at 75°C, but then you can “round up” to the next standard fuse size, which is 125A.
Run 3-#2Cu, one of them being marked white in some fashion. AND include a #6 bare or green for the grounding conductor.

The above is all based the premise you want to run Copper, sizes must be changed accordingly if you use Aluminum.

Jerry

 

[ELMO67]

Thanks for the info, guys, now when I get the wiring done I won't have to keep dragging an extension cord all over the place!

 

[bky]

Remember to keep the neutral bar isolated from the panel and keep all neutral (white) wires on it and add a ground bar and put all the ground (bare or green) wires on it and bond (connect the ground bar to the metal breaker box

 

[yooperdave]

BKY-

I was told by an electrical engineer and a electrical inspector that you only use the bonding screw to bond the main box and not the sub box.

Please verify.

Thanks

Yooper Dave

 

[bky]

yes true ion your main pannel. but in the sub pannel you have to bond the ground bar not the nuteral bar

 

[Inspector507]

bky,
There is always an exception........ /forums/images/graemlins/grin.gif
In a separate building you DO want to use it to bond the neutral bar to the cabinet if you don't pull a ground out, which is permissable.

Jerry

 

[bky]

Well if the panel is feed from the main panel from the house and you run to a separate building it is still considered a sub panel and at that point if you don’t take a ground out to it then you have to drive a ground rod and bond the ground wire to the ground bar and bond the ground bar to the panel but the neutral bar still needs to be isolated /forums/images/graemlins/laugh.gif

 

[Inspector507]

Correction........if you don't run a ground and there are no continuous metallic paths between buildings, you need to drive the ground rod AND connect it to the neutral bar. Neutral bar and ground bar are one in the same in this case.
Read Art. 250-32B2 of the 2002 NEC® /forums/images/graemlins/grin.gif

Jerry

 

[bky]

ok i will check that artical. now that you mention it ii do rember somthing about that at the last code change seminar . thanks for setting me stright. /forums/images/graemlins/blush.gif

 

[ELMO67]

Again, I thank everyone for their advice. I haven't yet decided which route I'll take, most likely it will be running a ground from panel to panel. TractorlessSacto- thanks for the reply, but especially for your last statement... " Or well meaning advice from some guy on the internet". I think that is advice anyone who surfs the Internet should read and remember.