Nec 680.21(a)(1)

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erickench

erickench

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The above NEC section exhibits an inconsistency. It states that an insulated equipment grounding conductor must be employed for the following wiring methods: Rigid Metal Conduit, Intermediate Metal Conduit, Rigid Nonmetallic Conduit and type MC cable. Now the RMC and the IMC are usable as equipment grounds and the MC cable if listed as "All Purpose" can also be an equipment ground, but not the rigid nonmetallic conduit. So in all these wiring methods you would have a double ground except the nonmetallic conduit which would have a single ground. Why should the nonmetallic conduit be different from the others?
 
Eric, 680.21(A)1 is saying that which ever wiring method you choose that is allowed, an equipment grounding conductor no smaller than a # 12 awg has to be ran with the raceway,or included with the cable.
Rick
 
Yes but why in all the indicated wiring methods only nonmetallic conduit has a single ground? Why run an insulated equipment grounding conductor in all the other methods and have two grounds as a result? That nonmetallic conduit sticks out like a sore thumb as compared to the other wiring methods. It's different.
 
Eric 680.21 is looking for a copper equipment ground conductor regardless if the raceway is metal or plastic.
 
Understood. That is what it says. I'm questioning the NEC rule itself. Why in the one(or two i.e. MC cable) case is there only one equipment ground?
 
Not really sure other than all the equipment is going to be bonded together with a # 8 awg as well as requiring the minimum # 12 awg ground.
Rick
 
Well it might have been better if they had excluded the nonmetallic conduit and indicate that the MC cable is listed as "All Purpose". This way it looks more consistent.
 
My guess would be that they want you to install the grounding conductor so that you are insured a good ground and are not relying on a mechanical means that could have been installed improperly. JMO
 
My guess would be that they want you to install the grounding conductor so that you are insured a good ground and are not relying on a mechanical means that could have been installed improperly. JMO


Probably. But the only thing is that the nonmetallic condut would be without a mechanical ground and therefore without a backup. This makes it different from all the other methods. I was wondering why they would include this in the rule.
 
But the only thing is that the nonmetallic condut would be without a mechanical ground and therefore without a backup. This makes it different from all the other methods. I was wondering why they would include this in the rule.
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The rule, is for the equipment grounding conductor run to a pool motor to be an insulated copper conductor. There is no requirement in this section that there be any redundancy of the equipment grounding conductor. The fact that there might be redundancy with certain wiring methods is purely coincidental.

Chris
 
I would have written it as saying that only nonmetallic conduit would have an insulated equipment grounding conductor. What's the point in having an additional EGC for a metal raceway when it already exists?
 
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