Generator and Manual Transfer Switch for 480 V Wye Service with Unused Neutral

[SnakNest]

Thanks to everyone for the input thus far. I'm going to try to make a visit to the site this week to verify the bonding / grounding questions that were raised with the fused switch, and check the origin of the grounding conductor that passes through the breaker enclosure vs the one that grounds that enclosure.

Regardless, I'll get input from the client to see how receptive they are to the idea of purchasing a new 5-wire cord / connector setup in the interest of avoiding any questionable code situations.

 

[hornetd]

I don't think this is correct. 250.6 only says you need to avoid Objectionable Current and there will not be any chance of that because all the loads being discussed are line to line.

Section 250.24 uses the prescriptive language "Shall Not." If forbids the grounding of the neutral on the load side of the service disconnecting Means. The code format changed with the 2020 edition. The first part of the article states what is to be done. The second part prescribes how it will be done. It is the second portion of the article that is used for enforcement. The critical words are shall, shall not... 250.24 Says "A Grounded Conductor Shall Not... be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article." To say that the article otherwise permits you have to find language in the article which says "May" followed by language describing a situation were "reconnected to ground" would be done.

Search or argue as you will you will not find language that permits the neutral of a generator that is connected to the neutral of the supply conductors on the load side of the service disconnecting means to be bonded to the frame unless that neutral is switched with the phase conductors which would change the generator to a separately derived system. If the neutral is not bonded to the frame of the generator Then the frame must be protected from accidental contact with an energized conductor by the installation of an Equipment Grounding Conductor to provide a low impedance pathway for fault current back to the main bonding jumper so that a fault will cause the generator over current protective device to open and interrupt the fault current before additional damage, electric shock, or electrocution can occur.

The conclusion that brings me to is that the connectors must be capable of connecting 5 conductors, to accommodate the addition of a EGC, to the supplied systems wiring.

 

[ActionDave]

250.24 says "Service Supplied"
250.24(A)"A premises wiring system supplied by a grounded ac service"
Everything under discussion is about generator supplied power, not service supplied power.

Section 250.24 uses the prescriptive language "Shall Not." If forbids the grounding of the neutral on the load side of the service disconnecting Means. The code format changed with the 2020 edition. The first part of the article states what is to be done. The second part prescribes how it will be done. It is the second portion of the article that is used for enforcement. The critical words are shall, shall not... 250.24 Says "A Grounded Conductor Shall Not... be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article." To say that the article otherwise permits you have to find language in the article which says "May" followed by language describing a situation were "reconnected to ground" would be done.

250.24 Grounding of Service-Supplied Alternating-Current Systems

(A) System Grounding Connections

A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

(1) General

The grounding electrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
Informational Note: See definitions of Service Conductors, Overhead; Service Conductors, Underground; Service Drop; and Service Lateral in Article 100.

I don't see the words Shall Not anywhere.

Search or argue as you will you will not find language that permits the neutral of a generator that is connected to the neutral of the supply conductors on the load side of the service disconnecting means to be bonded to the frame unless that neutral is switched

I don't have to find language that permits me to do anything. There is no language to stop me from driving 30 MPH in a 45 MPH zone.

 

[hornetd]

250.24 says "Service Supplied"
250.24(A)"A premises wiring system supplied by a grounded ac service"
Everything under discussion is about generator supplied power, not service supplied power.

250.24 Grounding of Service-Supplied Alternating-Current Systems

(A) System Grounding Connections

A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

(1) General

The grounding electrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
Informational Note: See definitions of Service Conductors, Overhead; Service Conductors, Underground; Service Drop; and Service Lateral in Article 100.

I don't see the words Shall Not anywhere.

I don't have to find language that permits me to do anything. There is no language to stop me from driving 30 MPH in a 45 MPH zone.

That's because you did not look at Section 250.24(A)(5) which reads; "A Grounded Conductor Shall Not... be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article." Doing that very thing is a code violation.

No competent electrical inspector is going to final the permit with such a connection in place. I realize that not all inspectors are competent, thorough, and willing to go to the extra work that withholding approval of the work will cause. If your only measure of quality is what you can get past the inspection authority then why discuss the code at all.

I "cut my teeth" on power production work while in the air force just out of high school. I learned that project managers; who, after all, get there "atta boys" by keeping costs down; will approve the purchase of anything marked "Optional" in the catalog. That was even true in the Air Force. Both the grounded conductor isolating kit and the 4th pole kit for the transfer switch are marked as optional

Go ahead and offer advise that will put the original poster in the trick bag. It's no skin off your nose right? When I undertake to answer a question which someone posts here I do my best to give them sound advise based on the code as written and not how I think it should have been written. To offer them anything else is a disservice not just to them but to the entire craft.

 

[ActionDave]

That's because you did not look at Section 250.24(A)(5) which reads; "A Grounded Conductor Shall Not... be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article." Doing that very thing is a code violation.

Why do I need to go down to (A)(5)? All I have to do is read the title- 250.24 Grounding of Service-Supplied Alternating-Current Systems.

When I undertake to answer a question which someone posts here I do my best to give them sound advise based on the code as written and not how I think it should have been written. To offer them anything else is a disservice not just to them but to the entire craft.

I don't see a portable generator meeting the definition of a service supplied alternating current system.

Article 100 Service. The conductors and equipment connecting the serving utility to the wiring system of the premises served.

 

[hornetd]

OK I get it. I've been successfully trolled by someone who is just playing with words. Congratulations on wasting the time of everyone who took the time to read your drivel.

 

[ActionDave]

You're welcome