Residential Grounding and bonding

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Johnhall30

Senior Member
Location
New Orleans, LA
Occupation
Engineer
I've seen the results of that myself many times and typically try to avoid doing it as well.

Had one last summer that was probably ~30 year or better installation. You probably know NPPD hasn't and still doesn't necessarily put weatherheads on their end of underground laterals that originate at top of a pole. This was one that likely was that way when initially installed, but a second structure to be supplied was added at some time and they just moved the meter to the pole, with a meter/main assembly, but never put a weatherhead on the top of the conduit. Surprised that main breaker lasted as long as it did, especially with aluminum wire in it. We replaced the breaker and had a weatherhead put on the conduit.
If the panelboard has any knockouts above or even with any of the busbars, weathertight gasketed locknuts should be used
 

Johnhall30

Senior Member
Location
New Orleans, LA
Occupation
Engineer
In theory, even though parallel paths exist between the neutral bar in the panel and the neutral termination within the meter can, the path of least resistance would be the larger neutral wire, which would carry most of the current. But objectionable current will still flow through the cabinet and GEC back to the source.
 

kwired

Electron manager
Location
NE Nebraska
If the panelboard has any knockouts above or even with any of the busbars, weathertight gasketed locknuts should be used
Yes, but that still doesn't stop condensation within the raceway, and it will happen in most areas, from draining onto your main lugs/main breaker when it is directly above them.
 

Buck Parrish

Senior Member
Location
NC & IN
But wait... An offset nipple is not allowed? I had no idea. I've used many of them for that purpose.


Come to think of it, most of mine have been plastic PVC.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
But wait... An offset nipple is not allowed? I had no idea. I've used many of them for that purpose.


Come to think of it, most of mine have been plastic PVC.
The issue is not the offset nipple itself but rather the threads. A PVC offset has the same issue. Offset nipples, PVC MAs, EMT connectors, etc. all have straight threads that are only listed for use with lock nuts.
I know it is crazy and is a common practice in many areas but a violation none the less.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Is the problem with "straight threads into hub" more than that is has not been tested to be a suitable bonding connection? Because I would say the bonding bushing in the picture in the OP sidesteps that issue; it doesn't need to be a bonding connection.

Cheers, Wayne
 

Buck Parrish

Senior Member
Location
NC & IN
I don't want to take away from the OPs topic. But it's kind of important. So if I use a straight PVC connector in a hub, it's okay? But not an offset nipple?
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
I don't want to take away from the OPs topic. But it's kind of important. So if I use a straight PVC connector in a hub, it's okay? But not an offset nipple?
No. As I stated in previous post, a PVC MA is only listed to use with lock nuts. The only thing you can use with a threaded hub would be threaded IMC or RGC
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Arent factory threads on rigid straight threads too? Seems like the coupling goes all the way on those. I know most threading machines are set for tapered threads, so if you cut the conduit and thread it may be a tapered pipe thread.

Does this mean you cant use a factory rigid thread in a hub?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Arent factory threads on rigid straight threads too? Seems like the coupling goes all the way on those. I know most threading machines are set for tapered threads, so if you cut the conduit and thread it may be a tapered pipe thread.

Does this mean you cant use a factory rigid thread in a hub?
All threads (factory and field cut) on RMC and IMC are tapered. The threads on an electrical coupling are straight.
 

kwired

Electron manager
Location
NE Nebraska
Never actually seen one in the wild but have seen in catalogs/online that there is PVC bolt on hubs for meter sockets, with slip/glue socket for the raceway. Not aware of Square D making one to fit their 3R bolt on setups similar to the one pictured in the OP though.
 
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