Missing neutral question

[wwhitney]

The conductors are run UG in nonmetallic conduits in close proximity to each other.

Unfortunately, the requirement in 310.10(H)(3) doesn't have any exception for nonmetallic conduits. Perhaps it should.

You could certainly run your neutral in proximity to the conduits in a single conductor direct buried cable. And then maybe you could argue that it would still comply with 310.10(H)(3) if that single conductor cable were inside the larger conduit (assuming it's big enough), since it's a cable type method, rather than a conductor that requires the conduit around it. Seems like that argument ought to work for something like ENT as an innerduct, if you had enough available conduit area to pull ENT in.

Cheers, Wayne

 

[ggunn]

lost track of if it was mentioned what this is, but it would still be do-able if outdoors as you have no length limit on feeder taps.

The scenario would be a 600A OCPD feeding two sets of 500kcmil conductors not connected on the other end from the disco with each set feeding different loads. That would be compliant?

 

[wwhitney]

The scenario would be a 600A OCPD feeding two sets of 500kcmil conductors not connected on the other end from the disco with each set feeding different loads. That would be compliant?

If at the load end you provide proper OCPD and if the 500 kcmil conductors are all outdoors, where unlimited feeder tap lengths are allowed. 240.21(B)(5)

Cheers, Wayne

 

[kwired]

The scenario would be a 600A OCPD feeding two sets of 500kcmil conductors not connected on the other end from the disco with each set feeding different loads. That would be compliant?

Is it inside a building?

Outside feeder taps have no length restriction.

However you can still run into issues with number of feeders supplying a separate structure if both end up at same location.

 

[ggunn]

Unfortunately, the requirement in 310.10(H)(3) doesn't have any exception for nonmetallic conduits. Perhaps it should.

You could certainly run your neutral in proximity to the conduits in a single conductor direct buried cable. And then maybe you could argue that it would still comply with 310.10(H)(3) if that single conductor cable were inside the larger conduit (assuming it's big enough), since it's a cable type method, rather than a conductor that requires the conduit around it. Seems like that argument ought to work for something like ENT as an innerduct, if you had enough available conduit area to pull ENT in.

Cheers, Wayne

In the 2020 NEC the exception to 300.4(B)(1) explicitly mentions non metallic UG raceways.

 

[wwhitney]

In the 2020 NEC the exception to 300.4(B)(1) explicitly mentions non metallic UG raceways.

[300.3(B)(1) Exception] OK, and that exception allows for isolated phase installations (and is redundant with broader allowance in 300.3(B)(3).) However, you aren't proposing an isolated phase arrangement, and nothing in 300.3 provides any relief from the requirements of (2020) 310.10(G)(3) on parallel installation. An isolated phase arrangement would still comply with 310.10(G)(3)'s requirement that each conduit have the same number of conductors, as long as the same number of sets is being used for each phase.

A couple further comments: a cheap trick to try to get a pass on 310.10(G)(3) is to just pull another #14 in the other conduit, and leave it unused. Now they all have the same number of conductors. That section doesn't say that the conductors should be same size.

Also, 310.10(G)(1) Exception 2 could be interpreted to apply to your situation and allow you to pull #2 neutrals into each conduit, if a #2 will fit in the smaller conduit, fill wise.

Cheers, Wayne

 

[ggunn]

[300.3(B)(1) Exception] OK, and that exception allows for isolated phase installations (and is redundant with broader allowance in 300.3(B)(3).) However, you aren't proposing an isolated phase arrangement, and nothing in 300.3 provides any relief from the requirements of (2020) 310.10(G)(3) on parallel installation. An isolated phase arrangement would still comply with 310.10(G)(3)'s requirement that each conduit have the same number of conductors, as long as the same number of sets is being used for each phase.

A couple further comments: a cheap trick to try to get a pass on 310.10(G)(3) is to just pull another #14 in the other conduit, and leave it unused. Now they all have the same number of conductors. That section doesn't say that the conductors should be same size.

Also, 310.10(G)(1) Exception 2 could be interpreted to apply to your situation and allow you to pull #2 neutrals into each conduit, if a #2 will fit in the smaller conduit, fill wise.

Cheers, Wayne

Unfortunately, the conductors in the smaller conduit are already in violation at 45.2% This project is a mess.

 

[electrofelon]

This project is a mess.

Well gotta have some adversity now and then to keep you from getting bored