Elevator Grounding Issue

[larrybartowski]

I'm in MN. A customer of mine is being required by the local electrical inspector to add a grounding conductor to each of 4 elevators feeds. 2 of the elevators are being fed underground and 2 overhead, and all are with aluminum conductors. 2 Questions:

1. Does each elevator need its own ground per code? Or if its sized properly can they all be grounded from 1 ground conductor run back to the main service?

2. Can the grounding conductor be strapped to the outside of existing conduit or run in a separate conduit altogether?

Another more expensive option would be to remove the existing aluminum conductors and replace with copper to make room for the grounding conductor. Any advice is appreciated.

 

[tom baker]

Grounding conductor is not a code term.
What color is it and what is its function?
Also "each elevator must have its own ground" is not clear. Look at the defintion of ground, is that what you mean?

 

[larrybartowski]

It's not? I'm looking at the definition of "grounding conductor" right now in my code book. Ya know the green one that usually doesn't carry the stuff?


The inspector wants each elevator feed to have its own ground/green conductor back to the main service.

I know I'll likely have to give him what he wants, but I'm wondering if code requres it. I'm also trying to figure out the best method for giving him what he wants.

 

[raider1]

It's not? I'm looking at the definition of "grounding conductor" right now in my code book. Ya know the green one that usually doesn't carry the stuff?


The inspector wants each elevator feed to have its own ground/green conductor back to the main service.

I know I'll likely have to give him what he wants, but I'm wondering if code requres it. I'm also trying to figure out the best method for giving him what he wants.

The term "Grounding conductor" was removed from the 2011 NEC due to the fact that the term is misused.

I think what you are asking is, do the elevator feeders require and equipment grounding conductor to be run with the circuit conductors to the elevator.

The elevators are required to be connected to an equipment grounding conductor and that conductor must be run with the feeder suppling the elevator.

300.3(B) is the code section that requires the EGC to be run with the other conductors of the circuit.

Chris

 

[roger]

What type of conduit is being used for these feeders?

Roger

 

[larrybartowski]

2 elevators are being fed from an existing underground 4" PVC feed and 2 are being fed from 2 existing overhead 2" EMT feeds.

The inspector wants a ground wire the same size as the circuit conductors, so just pulling a ground into the existing conduits isn't an option UNLESS the existing aluminum conductors are replaced with copper to make room for the ground.

 

[pete m.]

The inspector wants....

Then your customer should want to see some specific code references.

FWIW the 2"EMT raceways, if installed correctly, could qualify as an EGC. The two PVC raceways would need to have an EGC installed but I do not know where the inspector is coming up with the requirement for full size EGC?

Pete

 

[charlie b]

I'm looking at the definition of "grounding conductor" right now in my code book.

No, you are looking at the definition of, "grounding conductor, equipment." If you leave out the "e" word, you will confuse your audience.

Let's forget about elevators for a moment. Every feeder needs to include an EGC, regardless of what it feeds. Sometimes, the conduit can serve as an EGC, but certainly not if it is made of PVC.

My concern is over the inspector's requirement that the EGC be the same size as the ungrounded conductors. What is the reason for that? EGC's are sized on the basis of the overcurrent protection device, and the sizes appear on table 250.122. For an elevator load, it is a good bet that the feeder is large enough that the EGCs are no longer the same size as the ungrounded conductors.

By the way, what size(s) are the ungrounded conductors, and what are the ratings of the overcurrent devices serving these feeders?

 

[Jim W in Tampa]

The 2 EMT feeds are likely OK but had i installed it would have ground wire
As to the 2 in PVC you have a problem. You did not tell us conductor size so can not say if conduit fill will be issue.
If you can carefully pull them back out and add the ground. Sure you wont like it but you might need copper to win on pipe fill.
Inspectors should never use the word WANT. He either has code number or needs to look it up.

 

[roger]

As stated by the others, the emt raceways are EGC's themselves, see 250.118, the PVC will have to have EGC's sized per 250.122 installed with the ungrounded conductors.

Roger