Several circuits in same conduit

[ktm400sx]

Hi -
I am going to be running a 15amp 110 volt, 20 amp 115 volt and 30amp 115 volt circuit in the same conduit.
Iam a little confused as to where in the code I find the requirements for the ground conducter for this scanerio.
Any help would be greatly appreciated.

The conduit is metallic

 

[jtester]

In the "05 NEC, look at 250.122(C).

Jim T

 

[charlie b]

You also need to look at the ampacity of the conductors you are using for the three circuits. 210.15(B)(2)(a).

 

[Bob NH]

You also need to look at the ampacity of the conductors you are using for the three circuits. 210.15(B)(2)(a).

What version of NEC? My NEC 2005 doesn't have 210.15.

 

[charlie b]

Typo: Should have said 310.15(B)(2)(a).

 

[petersonra]

Typo: Should have said 310.15(B)(2)(a).

ground is not a current carry conductor.

 

[charlie b]

ground is not a current carry conductor.

I didn't say it was. But you do have three separate circuits (15 amp, 20 amp, and 30 amp) in the same conduit. That is at least six current-carrying conductors.

 

[infinity]

Since the conduit is metallic no additional EGC may be necessary.

 

[Smart $]

... That is at least six current-carrying conductors.

Could be six. At least four. They may be a 3?, 4-wire MWBC. Not likely, but we're speculating on possibilities here

 

[infinity]

Could be six. At least four. They may be a 3?, 4-wire MWBC. Not likely, but we're speculating on possibilities here

Wouldn't that be 3 CCC's if the neutral only carries the unbalanced load from the three circuits? I agree that until we hear back from KTM we're simply speculating. These could be all two wire circuits or fed from a 120/240 volt system.

 

[petersonra]

I didn't say it was. But you do have three separate circuits (15 amp, 20 amp, and 30 amp) in the same conduit. That is at least six current-carrying conductors.

good point. might need to kick the ground up to account for the increased size of the CC conductors.

 

[kbsparky]

IF you want to add a supplemental equipment grounding conductor in that metallic conduit, then a single #10 wire should suffice for all circuits, assuming the largest current-carrying conductor is a #10 as well.

 

[mattsilkwood]

IF you want to add a supplemental equipment grounding conductor in that metallic conduit, then a single #10 wire should suffice for all circuits, assuming the largest current-carrying conductor is a #10 as well.

i agree always go with the biggest conductor in the pipe and you are covered

 

[ibew613]

Gec

Gec

Unless spec. why the money and labor for egc. Conduit is perfect, can be better egc than installed wire. Remember to command more wage, we must be better than average.

 

[petersonra]

Unless spec. why the money and labor for egc. Conduit is perfect, can be better egc than installed wire. Remember to command more wage, we must be better than average.

Is this an opinion, or fact? And what are the criteria for determining "better"?

Just curious.

 

[charlie b]

Could be six. At least four. They may be a 3?, 4-wire MWBC. Not likely, but we're speculating on possibilities here

Are you saying that you can have a MWBC with three different branch circuit ratings? I think not. You have 6 CCCs here, not four.

 

[infinity]

Are you saying that you can have a MWBC with three different branch circuit ratings? I think not. You have 6 CCCs here, not four.

Why can't he run 4-#10 conductors and protect one circuit at 15 amps, one circuit at 20 amps and the third circuit at 30 amps?

 

[monkey]

Are you saying that you can have a MWBC with three different branch circuit ratings? I think not. You have 6 CCCs here, not four.

Is that really a violation? Why can't you run say a 15A and a 20A on a 1Ph system using a #12 neutral between them? I inquired about this once and I don't recall anyone saying it was not legal.

 

[iwire]

I re-used an existing 6/3 AC cable to supply 30 amp and 20 amp 120 volt loads.

There is no requirement that a MWBC have equal OCPDs on each leg.

 

[iwire]

Is this an opinion, or fact? And what are the criteria for determining "better"?

Just curious.

I believe it is a fact that a properly installed conduit system provides a lower impedance fault path than the EGC normally installed in the raceway.