can I run a single ground to 3 branch circuits?

[twd000]

This question has nothing to do with my electric brewery, but want to pose a wiring question to the experts here.

In my garage, I plan to run 3 branch circuits from the subpanel. They are all in a line (by design) just different lengths so I will be running individual conductors in 3/4" conduit. 12-gage wire, one 120V/20A and two 240V/20A circuits for woodworking tools. Using standard breakers, not GFI, so no worry about inducing ground faults. Can I run a single 12-gage ground conductor to the first box, then pigtail to the second and third box? This would save 2 conductors in a crowded conduit. Of course I will bring individual hot and neutral conductors for each circuit.

 

[brew_ny]

I have done it in my garage when running solid conductor in conduit because of room

is it correct as far as code goes ? I wouldn't know, does it work it does

the neutral and hot legs are going to their own breakers they all share the same ground bar in the panel

all the best

S_M

 

[DaleHair]

Yes, that's the way it is normally done.

 

[The10mmKid]

Running your wiring that way is proper.
You have plenty of room in your conduit. (assuming THHN wire)

http://www.allenelectric.com/referencedata/conduitfill.htm

You have room to pull a couple spare wires to the first box. I'd use a double box for that first one of the run.

'da Kid

 

[Onkel_Udo]

Depending on the amperage of the 240V circuit the 12 gauge may be undersized is the only issue I see. this was acceptable practice in the early 2000's NEC (2002?) for residential but I cannot guarantee it is now.

You would be amazed what you can pull (legally and physically) through a 3/4" conduit.

 

[bsperr]

I agree with everyone else that sharing the EGC between circuits should be fine. Depending on the type of conduit and boxes you use, and if you keep everything bonded, the conduit could be your EGC and you wouldn't need to run another wire. However, your 120v circuit in the garage has to be GFCI protected under the NEC (if you're concerned about code compliance). Sharing the EGC between circuits shouldn't cause the GFCI to trip. That would only happen on multi-wire branch circuits when your sharing the grounded (neutral) conductor.

 

[neild5]

This question has nothing to do with my electric brewery, but want to pose a wiring question to the experts here.

In my garage, I plan to run 3 branch circuits from the subpanel. They are all in a line (by design) just different lengths so I will be running individual conductors in 3/4" conduit. 12-gage wire, one 120V/20A and two 240V/20A circuits for woodworking tools. Using standard breakers, not GFI, so no worry about inducing ground faults. Can I run a single 12-gage ground conductor to the first box, then pigtail to the second and third box? This would save 2 conductors in a crowded conduit. Of course I will bring individual hot and neutral conductors for each circuit.

Having 7 current carring conductors in the conduit will require you to derate the current capacity each conductor can carry but otherwise it will work.

 

[DaleHair]

Having 7 current carring conductors in the conduit will require you to derate the current capacity each conductor can carry but otherwise it will work.

There are only 6 current carrying conductors, the ground does not count. Using THHN he will be fine.

 

[The10mmKid]

Here is a neat Derating, OCPD (Circuit Breaker) and voltage drop calculator:

http://www.electrician2.com/calculators/wireocpd_ver_1_reverse.htm

Carry on with your wiring, your good.

If you choose to use the 4-square/double box, I would loop your 220v runs inside and push them into the very back. It will give you some wire to play with if you want to make changes down the road.

'da Kid

 

[neild5]

There are only 6 current carrying conductors, the ground does not count. Using THHN he will be fine.

Actually there should be 8 wires,
120 v 20 amp- 2 wires 1 hot 1 neutral
240 v 20 amp- 3 wires 2 hot 1 neutral
240 v 20 amp- 3 wires 2 hot 1 neutral
Total 8 wires

I agree THHN wire is still fine but each 240 V circuit shold have a dedicated neutral back to the panel.

 

[DaleHair]

Actually there should be 8 wires,
120 v 20 amp- 2 wires 1 hot 1 neutral
240 v 20 amp- 3 wires 2 hot 1 neutral
240 v 20 amp- 3 wires 2 hot 1 neutral
Total 8 wires

I agree THHN wire is still fine but each 240 V circuit shold have a dedicated neutral back to the panel.

Why do you need a neutral for the 240v, I assumed they would be for heater element, 2 hot 1 ground

 

[The10mmKid]

There is no purpose for a neutral in the 220v circuits.

'da Kid

 

[CatchinZs]

There is no purpose for a neutral in the 220v circuits.

'da Kid

I'm not an electrician so please correct me if I'm wrong but that's not necessarily true if his woodworking tools have a control panel that run with 120 but are integrated into the 240 circuit.

 

[DaleHair]

I'm not an electrician so please correct me if I'm wrong but that's not necessarily true if his woodworking tools have a control panel that run with 120 but are integrated into the 240 circuit.

That would be a 120/240v outlet.

 

[twd000]

Yeah they're pure 240 so no neutral

 

[neild5]

I'm not an electrician so please correct me if I'm wrong but that's not necessarily true if his woodworking tools have a control panel that run with 120 but are integrated into the 240 circuit.

You are correct. Also it is cheapper to run the 2 extra wires now than have to redo it and add them if needs or intended usage changes later.

 

[Onkel_Udo]

I agree with everyone else that sharing the EGC between circuits should be fine. Depending on the type of conduit and boxes you use, and if you keep everything bonded, the conduit could be your EGC and you wouldn't need to run another wire. However, your 120v circuit in the garage has to be GFCI protected under the NEC (if you're concerned about code compliance). Sharing the EGC between circuits shouldn't cause the GFCI to trip. That would only happen on multi-wire branch circuits when your sharing the grounded (neutral) conductor.

For some stupid reason many local code enforcement agencies are misinterpreting the NEC for residential and outlawing the use of EMT as a the EGC. I understand the argument but I do not agree. As long as the ground path is never interrupted from fixture to ground bar, even poorly installed 1/2" EMT is a more than sufficient conductor. Just be aware that this VERY COMMON practice my not be allow in your jurisdiction.

 

[bsperr]

For some stupid reason many local code enforcement agencies are misinterpreting the NEC for residential and outlawing the use of EMT as a the EGC. I understand the argument but I do not agree. As long as the ground path is never interrupted from fixture to ground bar, even poorly installed 1/2" EMT is a more than sufficient conductor. Just be aware that this VERY COMMON practice my not be allow in your jurisdiction.

Good point. When in doubt, talk to your local inspector (if this will be a permitted job), because they make the call about what the code requires.

 

[Onkel_Udo]

Good point. When in doubt, talk to your local inspector (if this will be a permitted job), because they make the call about what the code requires.

By the way the argument is the same as the reason that grounding to a cold water pipe has been outlawed...You cannot guarantee that future remodel/upgrades will not break the ground path by installing non-metallic somewhere in between the fixture and the service entrance.

An example would be if you have a single run of EMT with three fixture boxes with a continuous ground path from metal box to metal conduit to metal box, etc, someone later could come along and replace one section of EMT with plastic conduit to insert another fixture between boxes one and two. Now two, and possibly three, fixtures have no ground path.

In the water line-as-ground I almost get this argument as I have replaced a section of galvanized line with a section of CPVC before...in and old house that used the cold water line as ground for retro-fitted 2-wire outlets. If I were an ignorant (not stupid) homeowner I would not have put a jumper over that section with ground clamps on either end. Without that jumpr, half my outlets would have lost the EGC if the tap water itself were not conductive enough (rust water from galvanized lines...not really an issue).