Steel LB Surrounded By PVC Conduit

Status
Not open for further replies.
A/A Fuel GTX

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
Is there any exception allowing a steel conduit body in the middle of a run of PVC to be ungrounded? This would be used in a run for a feeder.
 
It's a Mogal LB. By design, it's a lot easier to get 4/0 SER through vs a conventional LB. I'll just run 2" EMT from the bottom of the meter/main into the LB. That should take care of the grounding issue.
 
A/A Fuel GTX said:
It's a Mogal LB. By design, it's a lot easier to get 4/0 SER through vs a conventional LB. I'll just run 2" EMT from the bottom of the meter/main into the LB. That should take care of the grounding issue.
Click to expand...
You need to ensure that the SER bending radius when it goes through the LB is at least 5X the diameter of the cable {338.24}. More often than not unless the raceway is greatly oversized you cannot comply with the 5X rule.
 
don_resqcapt19 said:
You will have to find a way to bond the metal conduit body.
Click to expand...
another brilliant code technicality I presume. what really is the point of bonding if there is no break in the conductor.
I'm all about rules but ...really some inspector could call someone on that.
 
Another C10 said:
another brilliant code technicality I presume. what really is the point of bonding if there is no break in the conductor.
I'm all about rules but ...really some inspector could call someone on that.
Click to expand...
If a fault was to occur in the metal portion of raceway it can become energized and without bonding would not be able to clear fault. Granted one small peice such as the LB, chance is low but if the LB can be contacted by person or animal a risk of death or harm is there.
Now as far as making the connection between the threaded LB and PVC likely a techincal violation there also (like 344.6, 344.42(A), 352.6), as I'm not aware of a fitting that is listed to connect PVC to a threaded connection that is not using a nut. Every connector I'm aware of for PVC is designed and listed only for adapting to a box enclosure and uses a nut to secure fitting to the enclosure.
 
As to the need, other than being Code, from the number of times I've seen damaged conductors in an LB, grounding would be well warranted.
I have added a grounding lug as electrofelon suggested or using metallic conduit from the meter main as noted will solve the problem.
 
Another C10 said:
another brilliant code technicality I presume. what really is the point of bonding if there is no break in the conductor.
I'm all about rules but ...really some inspector could call someone on that.
Click to expand...
I would cite that, as one of the common places for a fault to occur in a conduit run is at a conduit body like an LB. It is a serious safety issue if an ungrounded conductor is faulted to an isolated metal LB.
 
electrofelon said:
Is anything that would specifically prohibit bolting a lay in lug to the LB?

Edit: I see that wasn't the OPs question, but to expand the topic....
Click to expand...
Good luck finding a factory thread on the LB, to attach that lug. And if you drilled/tapped your own lug, that would violate the product listing.

What I'd recommend for the OP, would be to install a short nipple, with about 2 inches exposed after threading it on both sides, and attaching a bonding strap or bonding U-bolt, to that segment of conduit. Then use a PVC female adapter to transition back to PVC. Attach a #6 Cu bonding jumper to connect from this bonding fitting, to something that is already properly bonded. Like using a cord grip for this wire to enter a nearby enclosure.
 
Carultch said:
Good luck finding a factory thread on the LB, to attach that lug. And if you drilled/tapped your own lug, that would violate the product listing.

What I'd recommend for the OP, would be to install a short nipple, with about 2 inches exposed after threading it on both sides, and attaching a bonding strap or bonding U-bolt, to that segment of conduit. Then use a PVC female adapter to transition back to PVC. Attach a #6 Cu bonding jumper to connect from this bonding fitting, to something that is already properly bonded. Like using a cord grip for this wire to enter a nearby enclosure.
Click to expand...
Not sure this meets code.
 
Another C10 said:
View attachment 2559749View attachment 2559752
Click to expand...
I believe you will find that a threaded lb is listed for and/or the instructions state for use with rigid threaded conduit. Kind of just a stupid technicality I don't think anybody really cares about, but the way to theoretically get around it is to use a RGS nipple and a female PVC adapter - because somehow the TA threaded into the LB will kill the bus full of nuns and kittens, but the FA on a nipple won't.
 
Also, other than killing the bus full, the threads on each pictured above while almost will fit is not exactly the same and will not seal properly. A rigid conduit thread is a tapered thread (npt) and used on the LB above, and is not the same as that used with a nut which is a straight thread used on the box adapter fitting above.
The use of the 2 pictured together as above would be a technical violation even though many might use them together. In dry area might not be as much of an issue other than the fitting might break as a result of the taper of the lb during installation, but in a wet area not using matching tapered fittings will allow water intrusion and if in a area of the country that freezes it can break the parts. (Seen it)
 
Status
Not open for further replies.
Top