Attach grounded conductor to service enclosure?

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Psychlo

Psychlo

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Location
Melissa, TX
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Master Electrician
I've got a residential client that had a panel fire (FPE, if you can believe it). All service entrance conductors (4/0 AL URD) were vaporized. The laterals (also 4/0 URD) were disintegrated back to the mouth of the 2" GRC downpipe. So, looking at the meter, you can barely see the melted stubs of the conductors in the top of the conduit. The laterals from the transformer (100 ft away) are direct-bury, under concrete slab and/or street asphault.

Provided that the conductors in the downpipe are uncompromised and usable, I plan to cut the downpipe at about 18" above slab and put a 3R enlcosure -- then splice on new conductors to feed through a new meter, etc.

Question:

Will I need to attach the grounded conductor to the splice enclosure? Or would a #4 Cu bond wire from the panel be sufficient?
 
augie47 said:
Either way should be acceptable.
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I was thinking as much. But sometimes service bonding dos and don'ts throw me for a loop. Once I got dinged by the AHJ for running service conductors through EMT (in a church basement). It turns out that Washington has a special restriction against using EMT for service conductors (still unsure why). So I learned that one the hard way, and had to re-run it in PVC. Thanks for the affirmation.
 
Wouldn't you be required to replace the entire service? If you have to replace the panel and repair the lower feeders, wouldn't that be over 50% of the service?

(maybe I'm thinking of a local thing but when we have to do anything more than replace the panel, we have to do an entire service change)
 
If you have conductors ahead of the meter (laterals) would not these conductors be under the control of your utility?, here it would.

If not why not just do an underground water proof splice and re run up into the meter, but I can not see that this meter did not receive damage, as I'll bet it needs to be replaced as well, as well as the inside of any involved pipe now has sharp burned ends of wire in it that can damage any new wire put back in it.
 
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Psychlo said:
I was thinking as much. But sometimes service bonding dos and don'ts throw me for a loop. Once I got dinged by the AHJ for running service conductors through EMT (in a church basement). It turns out that Washington has a special restriction against using EMT for service conductors (still unsure why). So I learned that one the hard way, and had to re-run it in PVC. Thanks for the affirmation.
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your looking at what happens to shorted unprotected service conductors and ask Why EMT is not a good idea?
 
Not sure about other utilities, but here, if the 3R box was sealable, it would probably be OK. No different than a bussed enclosure feeding multiple meter panels.
 
K_Buz said:
Wouldn't you be required to replace the entire service? If you have to replace the panel and repair the lower feeders, wouldn't that be over 50% of the service?

(maybe I'm thinking of a local thing but when we have to do anything more than replace the panel, we have to do an entire service change)
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Yep, I'll be replacing the entire service, but my main question was regarding the grounded conductor attachment. This is the first time in 16 years that I've had to put a splice box in a service downpipe, so I've never had to consider it before.
 
hurk27 said:
If you have conductors ahead of the meter (laterals) would not these conductors be under the control of your utility?, here it would.

If not why not just do an underground water proof splice and re run up into the meter, but I can not see that this meter did not receive damage, as I'll bet it needs to be replaced as well, as well as the inside of any involved pipe now has sharp burned ends of wire in it that can damage any new wire put back in it.
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Here, service laterals are owned and serviced by the customer, but the utility still has some say over how they are to be installed.

The downpipe emerges from a concrete slab, so that is why I want to stay away from an in-ground splice. I'll see what the extent of the damage to the pipe was when I cut into it about 3' down from the meter. I expect it will be ok.
 
hurk27 said:
your looking at what happens to shorted unprotected service conductors and ask Why EMT is not a good idea?
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I guess I figure that can happen to any metallic conduit. So why is EMT singled-out as the only prohibited method? RMC, IMC, and I suppose even flex could be used. Seems counter-intuitive to me. It's not an NEC thing, just WA state. I guess electricity behaves differently here than elsewhere....
 
John120/240 said:
What is the reasoning that PVC is a better choice than EMT ?
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I don't know, but I just dug up the code reference:
WAC 296-46B-230 says:

043 Wiring methods for 600 volts, nominal or less.

(7) The installation of service conductors not exceeding 600 volts, nominal, within a building or structure is limited to the following methods: Galvanized or aluminum rigid metal conduit; galvanized intermediate metal conduit; wireways; busways; auxiliary gutters; minimum schedule 40 rigid polyvinyl chloride conduit; cablebus; or mineral-insulated, metal-sheathed cable (type MI).

(8) Electrical metallic tubing must not be installed as the wiring method for service entrance conductors inside a building. Existing electrical metallic tubing, installed prior to October 1984, which is properly grounded and used for service entrance conductors may be permitted to remain if the conduit is installed in a nonaccessible location and is the proper size for the installed conductors.

This eliminates my supposition that flex might be ok, but what about MI cable? Does that not strike anyone else as strange? I'm still scratching my head.
 
I also scratched my head over the emt pvc deal. The whole time I was changing it out on a panel replacement in the basement of a summer cottage. Existing panel was an old fpe as well and the meter was on the front porch. Emt in the wall down to the edge of the basement wall and neatly run over and into the service panel. Got a correction and had to remove the metal pipe and replace it with 40 pvc. The logic of this escapes me to this day. No flex I can but but no emt? wish someone frome Washington could explain the logic for this.Cannot figure out why we diverge from NEC on this.
 
Just curious, do you know what caused the melt down originally? the last fpe panel I saw burn was caused by the neutral from the POCO getting cut. Hoffman makes an enclosure that has lugs in it and is perfect for underground feeders that need extending or relocating.
 
K_Buz said:
Does the salt in the air from the ocean have anything to do with emt corroding prematurely?
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I'm 200 miles from the coast. I would hope that there wouldn't be statewide code just because there was an issue with a coastal environment.
 
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