Grounding electrode conductor raceway.

[slo7682]

A grounding spec that I reviewed recently asked for the grounding electrode conductor that is routed throughout the building connecting the main ground bar in the main electrical room to remote ground bars in branch electrical and telecom rooms to be non-magnetic conduit. What is the reason for this? Can the conduit be PVC, or should it be aluminum? What is wrong with standard steel EMT? The conduit I presume is for protection. Can it or should it be left open?

 

[dereckbc]

Re: Grounding electrode conductor raceway.

The steel conduit presents a choke or girdling effect for a single conductor. In other words it adds considerble inductance and raises the high frequency impedance.

You can use PVC. Just be careful not to use steel straps that encircle the conduit. Most Telcos just run it in open air unless AHJ objects.

 

[ryan_618]

Re: Grounding electrode conductor raceway.

In addition to what Dereck said, take a look at 250.64(E).

 

[sdbob]

Re: Grounding electrode conductor raceway.

Originally posted by dereckbc:
The steel conduit presents a choke or girdling effect for a single conductor. In other words it adds considerble inductance and raises the high frequency impedance.

Is this still true if the steel conduit is bonded to the conductor on both ends?

 

[dereckbc]

Re: Grounding electrode conductor raceway.

Originally posted by sdbob:
Is this still true if the steel conduit is bonded to the conductor on both ends?

No, but if your talking about long distances with several sections of pipe, then joint integrity comes into play. I have done it three ways:
Open Air
PVC
Steel conduit bonded at both ends.

Some locations I work with are exempt from NEC so in those areas I use open air. All others what ever the AHJ will let me get away with. Some open air, mostly PVC, and a few steel.