Grounding Bushing 1999 NEC 250-64(e)

[ed downey]

If I have a piece of EMT that is run in a block wall and stubbed out near the structural steel overhead.
I then run a THHN copper conductor (equipment grounding conductor) from a transformer at the floor into the conduit and then out the top of the conduit then cadweld the conductor to the building steel.

Per the 1999 NEC 250-64(e) do I need a grounding bushing on each end of the conduit?, or just one end?, or not at all?
If a grounding bushing is required is this because of the potential for the length of conduit to become energized even though it is an insulated conductor?

Thanks,
Ed

[ October 28, 2003, 05:28 PM: Message edited by: ed downey ]

 

[tom baker]

Re: Grounding Bushing 1999 NEC 250-64(e)

A metalic conduit containg a grounding electrode conductor has to be bonded at each end, all boxes in between have to be bonded as well. this is to prevent an impedance choke from restircting the high current/voltage pulse from a lighting event (it will restrict up to 97%)
However, unless this is a time and materials job, why not use schedule 80 PVC?
Depending on the location you could run the GEC exposed, if it was 4 AWG....but PVC (only sch 80 for physical protection per the UL listing) is better.

 

[ed downey]

Re: Grounding Bushing 1999 NEC 250-64(e)

Thanks, Tom

This Conductor Is Currently Installed In EMT In A Block Wall So A Grounding Bushing At Each End Will Be Installed.

 

[pirate77]

Re: Grounding Bushing 1999 NEC 250-64(e)

Re: Running a GEC in PVC, MUST it be in Schd.80,
or can Schd.40 be used? I only had 10' to go to
bldg. steel.
Thanks

 

[roger]

Re: Grounding Bushing 1999 NEC 250-64(e)

Pirate, no, you do not have to use schd 80.

See article 250.64(B) for some more info.

Roger

 

[rickg]

Re: Grounding Bushing 1999 NEC 250-64(e)

I believe the conductor that is attached to the bond bushing must be the same size as the conductor inside the EMT. Any comments?

 

[tom baker]

Re: Grounding Bushing 1999 NEC 250-64(e)

Roger: the UL listing for PVC conduit states that where physical protection is required, then Sch 80 PVC must be used. If not exposed to physcial damage then sch 40 can be used.

 

[roger]

Re: Grounding Bushing 1999 NEC 250-64(e)

Hello Tom, Pirate's post didn't mention "physical damage" he simply asked if a GEC had to be installed in Schd 80.

Also, what are the oppinions on "exposed to physical damage" or "exposed to severe physical damage" being enforcible. It seems to me these terms are as vague as "workmanlike"

We know what sloppy work is, and we know what a fork lift can do to any conduit.

Roger