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Old 07-09-2012, 03:37 PM   #1
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new sub panel for 12-3 feed to detached garage


Hello all,

First time homeowner trying to straighten up some out of date wiring in a detached garage. The garage has a 12-3 UF run to an old box with 4 20 amp breakers, two of which were hooked up, 2 not. One circuit for receps, one for lights. The plastic housing on breakers is cracked so they don't snap on tight anymore. I'm starting from scratch within the garage as I'm changing locations of lights and receps. However I am stuck with the feeder as I don't feel like digging up my flagstone patio at this time. Feeder has red, black, and white wires. Red and black to the lugs, white to a neutral bus bar with grounds from receps and lights going there as well. No grounding bus bar present, no ground rods. Whats the safest way to rewire without running a 4 wire feeder? Is the way it was wired before safe?

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Old 07-09-2012, 03:48 PM   #2
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new sub panel for 12-3 feed to detached garage


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Originally Posted by alscich View Post
garage has a 12-3 UF run to an old box with 4 20 amp breakers
I am stuck with the feeder as I don't feel like digging up my flagstone patio
No grounding bus bar present, no ground rods.
You're grandfathered in if you leave it all alone.
If the future use is the same (misc L&R in a garage) there should be no reason to need to change anything

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Whats the safest way to rewire without running a 4 wire feeder?
If it were my house?
I'd add a ground rod and ground bar and separate the neutrals

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Old 07-09-2012, 03:55 PM   #3
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new sub panel for 12-3 feed to detached garage


Leave it all alone as in not changing out the breakers that are falling apart? Or can I switch out the box and breakers and wire it the same way and be grandfathered in?
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Old 07-09-2012, 04:13 PM   #4
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new sub panel for 12-3 feed to detached garage


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Leave it all alone as in not changing out the breakers that are falling apart?
Is that what you're asking about? I thought it was the feed/grounding.
If you have a faulty breaker then of course replace that.

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Or can I switch out the box and breakers and wire it the same way and be grandfathered in?
One bridge at a time...

Changing anything opens you up to how the inspectors in your town operate.
What you can do at the mechanical level, what will work or not is a different matter.
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Old 07-09-2012, 04:19 PM   #5
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new sub panel for 12-3 feed to detached garage


Thanks for the replies, I'm planning on installing a new sub panel with new breakers due to the condition of the old ones. I guess where I'm uncertain is whether I should install ground rods or duplicate the previous way it was wired.
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Old 07-09-2012, 04:32 PM   #6
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new sub panel for 12-3 feed to detached garage


Three wire feeder were allowed under previous editions of the NEC as long as no metallic paths between the building existed like a phone or water line. The neutral was again bonded as a service panel.

You would need to install at least one ground rod or other type of electrode.
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Old 07-09-2012, 05:24 PM   #7
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new sub panel for 12-3 feed to detached garage


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If it were my house?
I'd add a ground rod and ground bar and separate the neutrals
Whoa there! You DEFINITELY can't do that. That would leave the grounding system unbonded, which is a disaster waiting to happen. A fault to ground would not trip a breaker, but would electrify the whole grounding system. Unless there is a 4-wire feed with an N-G bond upstream, you MUST bond neutral and ground.
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Old 07-09-2012, 05:24 PM   #8
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new sub panel for 12-3 feed to detached garage


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If it were my house?
I'd add a ground rod and ground bar and separate the neutrals
If you did that, how would a ground fault clear?
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Old 07-09-2012, 05:28 PM   #9
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new sub panel for 12-3 feed to detached garage


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Originally Posted by alscich View Post
Hello all,

First time homeowner trying to straighten up some out of date wiring in a detached garage. The garage has a 12-3 UF run to an old box with 4 20 amp breakers, two of which were hooked up, 2 not. One circuit for receps, one for lights. The plastic housing on breakers is cracked so they don't snap on tight anymore. I'm starting from scratch within the garage as I'm changing locations of lights and receps. However I am stuck with the feeder as I don't feel like digging up my flagstone patio at this time. Feeder has red, black, and white wires. Red and black to the lugs, white to a neutral bus bar with grounds from receps and lights going there as well. No grounding bus bar present, no ground rods. Whats the safest way to rewire without running a 4 wire feeder? Is the way it was wired before safe?




EDIT, ehhh, nevermind.... forgot you can't extend a non grounded circuit, stick with a small panel, bond the neutral and grounds together, and drive a ground rod.

Last edited by stickboy1375; 07-09-2012 at 05:33 PM.
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Old 07-09-2012, 05:33 PM   #10
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new sub panel for 12-3 feed to detached garage


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Here is what I would do, scratch the panel all together, now you have a branch circuit not a feeder, I would land the 12-3 UF into a 4" sq. box, install two GFCI's. one fed by the black circuit, one fed by the red circuit, neutrals must be spliced together.... now off the LOAD side of these GFCI's, i would feed the receptacles off the black circuit, keep the lights on the red circuit... now you don't need ground rods. WOO-HOO!!!!
Exactly.

Besides, a 20A feeder is not code complaint. 30A minimum.
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Old 07-09-2012, 05:35 PM   #11
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new sub panel for 12-3 feed to detached garage


Quote:
Originally Posted by stickboy1375
Here is what I would do, scratch the panel all together, now you have a branch circuit not a feeder, I would land the 12-3 UF into a 4" sq. box, install two GFCI's. one fed by the black circuit, one fed by the red circuit, neutrals must be spliced together.... now off the LOAD side of these GFCI's, i would feed the receptacles off the black circuit, keep the lights on the red circuit... now you don't need ground rods. WOO-HOO!!!!


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Originally Posted by Speedy Petey View Post
Exactly.
Sorry Speedy, I edited it because you cannot extend a non grounded circuit... my bad...

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Originally Posted by Speedy Petey View Post
Besides, a 20A feeder is not code complaint. 30A minimum.
Sure it is, only the disconnect has to be rated at 30 amps.

check out 225.39 (B)Rating of Disconnect

Last edited by stickboy1375; 07-09-2012 at 05:38 PM.
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Old 07-09-2012, 06:28 PM   #12
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new sub panel for 12-3 feed to detached garage


If I do what you suggest with the branch circuit instead of the box and breakers how is it grounded? Or does it not need to be? Thanks
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Old 07-09-2012, 06:31 PM   #13
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new sub panel for 12-3 feed to detached garage


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If I do what you suggest with the branch circuit instead of the box and breakers how is it grounded? Or does it not need to be? Thanks
You're stuck with the panel my friend, just buy a 2 circuit panel and bond the neutral and grounds together, and drive a ground rod. This really is the only solution for you.

Last edited by stickboy1375; 07-09-2012 at 06:34 PM.
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Old 07-09-2012, 06:31 PM   #14
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new sub panel for 12-3 feed to detached garage


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Sorry Speedy, I edited it because you cannot extend a non grounded circuit... my bad...
I never even noticed that that was the case.
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Old 07-09-2012, 06:35 PM   #15
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I never even noticed that that was the case.
I know, I so missed the non existing grounding conductor...

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