Location, secondary OCPD

[chris kennedy]

Under 2008 here and can't find where the secondary OCPD for a 75kva 480D 208y/120 has to be located. Can I use a main breaker panel in a tenant space if the tranny is in the adjacent electrical room?

Thanks

 

[Dennis Alwon]

Chris I do not see anything in the 2008 but I see an added section in 2011

450.14 Disconnecting Means. Transformers, other than
Class 2 or Class 3 transformers, shall have a disconnecting
means located either in sight of the transformer or in
a remote location. Where located in a remote location,
the disconnecting means shall be lockable, and the location
shall be field marked on the transformer.

 

[augie47]

Keep in mind, unless otherwise alloed by 240.21(C), your secondary OCP must comply with the secondary rules of 240.21 which in most cases will put your OCP within 25 ft of the transformer.

 

[Smart $]

Chris I do not see anything in the 2008 but I see an added section in 2011

The required disconnecting means would be on the primary side, so not applicable to secondary protection ocpd location.

 

[Smart $]

Keep in mind, unless otherwise alloed by 240.21(C), your secondary OCP must comply with the secondary rules of 240.21 which in most cases will put your OCP within 25 ft of the transformer.

That's right. There is no specified location for a transformer secondary OCPD, but 240.21(C) and 240.92(C) requirements for secondary conductor protection force the secondary conductor and transformer secondary protection device (if there is one) to be one and the same.

 

[Dennis Alwon]

I agree with the others however Chris wanted to know if the disconnect had to be in the same room, I believe

 

[don_resqcapt19]

Under 2008 here and can't find where the secondary OCPD for a 75kva 480D 208y/120 has to be located. Can I use a main breaker panel in a tenant space if the tranny is in the adjacent electrical room?

Thanks

The length of the wire from the transformer secondary terminals to the first OCPD is limited by the rules in 240.21(C). If the wire length is short enough, you could do as you suggest.

 

[Carultch]

Keep in mind, unless otherwise alloed by 240.21(C), your secondary OCP must comply with the secondary rules of 240.21 which in most cases will put your OCP within 25 ft of the transformer.

240.21(C) only applies to customer-owned transformers, where the conductors are thus classified as transformer secondary conductors.

For utility-owned transformers, the secondary conductors are classified as service conductors, and 240.21(C) doesn't apply. Service conductor rules apply instead.

 

[augie47]

240.21(C) only applies to customer-owned transformers, where the conductors are thus classified as transformer secondary conductors.

For utility-owned transformers, the secondary conductors are classified as service conductors, and 240.21(C) doesn't apply. Service conductor rules apply instead.

Thank you for letting me know that
I assumed (foolishly) since he asked about a 480D/208Y-120 that it was customer owned as I have yet to see a service transformer with that rating

 

[Carultch]

Thank you for letting me know that
I assumed (foolishly) since he asked about a 480D/208Y-120 that it was customer owned as I have yet to see a service transformer with that rating

It's a reasonable assumption. Most, if not all, utility-owned transformers will have a medium voltage side.

 

[chris kennedy]

Thanks all, I was aware of the requirements of 240.21 and that's not a player here. (Tranny back to back with PLN.) Just was under the impression the secondary OCPD needed to be located near the tranny.

Being still under the 2008 but having in my possession and read the 2011 and 2014 I have too many code cycles in my head. As Dennis pointed out in post 2 what I was thinking of was the change in the primary OCPD rules.

Thanks again.

 

[augie47]

Thanks all, I was aware of the requirements of 240.21 and that's not a player here. (Tranny back to back with PLN.) Just was under the impression the secondary OCPD needed to be located near the tranny.

Being still under the 2008 but having in my possession and read the 2011 and 2014 I have too many code cycles in my head. As Dennis pointed out in post 2 what I was thinking of was the change in the primary OCPD rules.

Thanks again.

I can sure relate.... TN is still under the '08... "thinking about" adopting the '11 and the State IAEI holds seminars on the '14.. go figure.....

 

[Carultch]

I can sure relate.... TN is still under the '08... "thinking about" adopting the '11 and the State IAEI holds seminars on the '14.. go figure.....

Suppose you happen to have a job in a state that is still on an older version of the NEC, such as NEC2008. Are you permitted to take advantage of more permissive rules in 2014 that are not yet accepted in places where 2008 applies?

As an example, listed PV wire of all sizes is now permitted in cable trays as of NEC2014. In NEC2008, that is not the case. It was more of an issue of semantics than any real world consequences. Most AHJ's would approve it anyway.

One reason this might happen unintentionally, is in the event that you work in a state on NEC2014, and you've scrapped your old books. Then you happen to be working on an out-of-state job, and reference rules from NEC2014 without thinking that they are new rules. Or perhaps you are new to the trade, and never learned NEC2008.

 

[augie47]

Suppose you happen to have a job in a state that is still on an older version of the NEC, such as NEC2008. Are you permitted to take advantage of more permissive rules in 2014 that are not yet accepted in places where 2008 applies?

As an example, listed PV wire of all sizes is now permitted in cable trays as of NEC2014. In NEC2008, that is not the case. It was more of an issue of semantics than any real world consequences. Most AHJ's would approve it anyway.

One reason this might happen unintentionally, is in the event that you work in a state on NEC2014, and you've scrapped your old books. Then you happen to be working on an out-of-state job, and reference rules from NEC2014 without thinking that they are new rules. Or perhaps you are new to the trade, and never learned NEC2008.

As far as I know the legal answer is that you would need to comply with the adopted Code.
90.4 gives the AHJ the authority to permit alternative methods where it can be assured equivalent objectives are attained.
I have seen such "variances" approved by the AHJ and I have also seen some jurisdictions where such a change would need to be presented to a variance board.