[ddsrph]

I am starting to wire my new detached garage. I want to have two twenty amp circuits for the wall plugs. The interior walls will be covered with white steel roofing sheets run horizontal and all wiring will be on the surface in metal boxes connected by thin wall electrical metal conduit. For the two 120 volt 20 amp wall plug circuits I plan to run both in the same1/2 inch conduit. This will mean two black, two white and will I need two green grounds or will one be enough? Circuit one will first four receptacles and the other black and white will continue on to power circuit 2 the last four receptacles. The question is can the 1/2 thin metal conduit carry five #12 wires and if separate grounds are needed six #12?

Thanks
JM

 

[Shadow99]

I'd just run a MWBC , 2 hots, 1 noodle and 1 ground.

Either way, you're good for up to 9 THHN in 1/2" EMT

 

[rjniles]

You can not by code run 2 circuits to a detached garage. You can run a MWBC (multi wire branch circuit). Run from a 2 pole 20 amp breaker; 2 hots, a single neutral and a single ground.

 

[chandler48]

Agree with Shadow, you can only run one circuit to a detached building, so a MWBC would be best. Just make sure your noodle is cooked

 

[ddsrph]

I was just referring to a portion of the overall wiring. I have already run #6 conductors from house thru underground conduit to garage. In garage I will have the two circuits already mentioned plus a 220 for welder, a 220 for small ptac heat pump, and a lighting circuit. The wires in place from house 60 amp breaker are three (#6)white, black, red plus a # 8 green ground.

 

[rjniles]

I was just referring to a portion of the overall wiring. I have already run #6 conductors from house thru underground conduit to garage. In garage I will have the two circuits already mentioned plus a 220 for welder, a 220 for small ptac heat pump, and a lighting circuit. The wires in place from house 60 amp breaker are three (#6)white, black, red plus a # 8 green ground.

Your install is a code violation. You can only have one circuit to an outbuilding. You need a sub panel for all the circuits you propose.

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[chandler48]

You will find that we are pretty particular with information, and that is why we ask so many questions. We can only assume that you have a sub panel in the garage with the breakers installed in it, and that is is grounded with two grounding rods, the neutrals separated and islolated from the grounds.

 

[Shadow99]

I was just referring to a portion of the overall wiring. I have already run #6 conductors from house thru underground conduit to garage. In garage I will have the two circuits already mentioned plus a 220 for welder, a 220 for small ptac heat pump, and a lighting circuit. The wires in place from house 60 amp breaker are three (#6)white, black, red plus a # 8 green ground.

I'd still go with the MWBC if it were me. Unless there are AFCI and/or GFCI requirements where you are for a detached structure.
But you're good for 9 #12s in the 1/2"

 

[Shadow99]

Your install is a code violation. You can only have one circuit to an outbuilding. You need a sub panel for all the circuits you propose.

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Thanks RJ, I just assumed he had a sub.

 

[ddsrph]

Thanks all for the replies. I have a QO subpanel. I was planing on using two ground fault receptacles one at the head of each of the two 120 volt outlet circuits. The subpanel will be in one corner and the two 220 volt outlets will be just around the adjacent corner. Would it be ok to run a 3/4 inch thin metal conduit from box about four feet above floor which would carry all the wires for the 120 and 220 receptacles. (Six # 10 and six #12)?
The 3/4 inch (later dropping to 1/2 inch) would run around three sides of garage. I would exit for each receptacle as this conduit passed thru 4 by 4 metal boxes. When it got further down stream and number of wires got smaller drop conduit down to 1/2 Inch. The remaining lighting circuit would go straight up from box into attic. We are still using 2008 codes here in TN. I asked the inspector when he came to look at my underground conduit about ground rods and he said one only. I made sure I was hearing correctly as I was expecting two.

 

[Oso954]

I'd still go with the MWBC if it were me. Unless there are AFCI and/or GFCI requirements where you are for a detached structure.

Per the NEC, All garage 120v 15 or 20 amp receptacles have required GFCI for years, whether attached or detached.

I have read that NEC 2017 has added significantly to those requirements.

 

[pigman#1]

the inspector is requiring GFI plugs in my new pole barn project.....he says any 120v circuit requires GFI I think code says 15 and 20 amp 120 or 240 volts circuits

but he said only 120v so that's what I will do....;-)

 

[ddsrph]

You probably already know this but one GFI receptacle will protect six down stream regular receptacles which is what I plan to do.

 

[pigman#1]

You probably already know this but one GFI receptacle will protect six down stream regular receptacles which is what I plan to do.

I did know about the down stream but was not sure of how many......thanks for the info.......do you have any ideas of a somewhat cheap way to put GFI on 20 30 or 50 amp 240volts
so far my inspector is not requiring GFI's on 240v but I am just wondering at this point

 

[ddsrph]

Double check that 6 downstream I mentioned but I think that is the number. I would just go with the current code per inspector in your area regarding ground fault requirements. When I wired my new house last year (diy amateur) I put my labor savings into better materials like commercial 20 amp receptacles thru-out, commercial and industrial rated switches, 4 by 4 metal boxes with mud rings screwed to studs etc. no 14 gauge wire except for smoke detectors. In attic all wiring is on plywood tracks not covered up by insulation. Basically the kind of job that can't be done if cost of materials or labor is a consideration.

 

[rjniles]

There is no limit of receptacles in the NEC that can be protected downstream from a GFCI receptacle or breaker.

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