What are these conductors called?

[hhsting]

I have customer owned 13.2kv delta to 480/277V wye customer owned transformer. Primary of the transformer also belongs to customer.

The customer owned transformer one set feeds switchboard and another set of secondary conductors feed fire pump controller. The line side of the fire pump is connected to jockey pump.

In the below attached sketch conductor that connect the fire pump controller supply conductors on line side to jockey pump is circled green. The green circled conductors cant be feeder taps since their is no overcurrent protection device upstream. What are the green conductors? If they are tap conductors then I don’t see it in NEC 2017 Article 695 as call them tap conductors.

 

[jim dungar]

They are transformer secondary conductors, subject to 240.21(C). My first thought is they need to go all the way back to the transformer. But I waver a little if they are the same size as the conductors to the fire pump. But, I do know you cannot use 240.21(B) to create a tap from a 240.21(C) conductor.

 

[Tyler C]

Which part of 240.21 allows this? They appear to be transformer secondary conductors, but transformer secondary conductors must feed a single load, which is not the case here. When this is done from a service it is clear, but once you are in 240 this doesn't appear to be explicitly permitted.

 

[hhsting]

They are transformer secondary conductors, subject to 240.21(C). My first thought is they need to go all the way back to the transformer. But I waver a little if they are the same size as the conductors to the fire pump. But, I do know you cannot use 240.21(B) to create a tap from a 240.21(C) conductor.

They are not the same size as the fire pump supply conductors.

You are allowed to supply jockey pump from fire pump supply conductors NEC 2017 Article 695.6(B)(1). Their is no exception to that if its customer owned transformer either

I dont see how what your saying has to go back to all the way to customer owned transformer apply here?? Even NEC 2017 Exhibit 695.5 shows it and in their it is not going back to the transformer.

 

[jim dungar]

I dont see how what your saying has to go back to all the way to customer owned transformer apply here??

Is the transformer in the OP dedicated to the fire pump and associated equipment, like the one in the exhibit 695.5?

 

[hhsting]

Is the transformer in the OP dedicated to the fire pump and associated equipment, like the one in the exhibit 695.5?

No it supplies switchboard thru another set of transformer conductors. This is multi building campus style complex.

But I dont see exception in NEC 2017 Article 695.6(B)(1) either that non dedicated customer owned transformer cannot supply jockey from fire pump supply

 

[don_resqcapt19]

Not sure I see anything in the 2017 Article 695 that permits the installation. The rules for a campus style distribution system only address feeder conductors. They don't address transformer secondary conductors. It also appears to me that this will also require an alternate power source for the fire pump.

 

[hhsting]

Not sure I see anything in the 2017 Article 695 that permits the installation. The rules for a campus style distribution system only address feeder conductors. They don't address transformer secondary conductors. It also appears to me that this will also require an alternate power source for the fire pump.

Yes they have generator as alternate source and the fire pump controller is also has ats in it.

Would not NEC 2017 Article 695.6(B)(1) permit the connection of jockey pump to fire pump supply conductors?

 

[jim dungar]

But I dont see exception in NEC 2017 Article 695.6(B)(1) either that non dedicated customer owned transformer cannot supply jockey from fire pump supply

Yes a feeder to a fire pump can also feed a jockey pump.

I believe the issue is the transformer is not dedicated to the fire pump. The last one I designed like this, decades ago, required an OCPD between the transformer and the FP.

 

[don_resqcapt19]

Yes they have generator as alternate source and the fire pump controller is also has ats in it.

Would not NEC 2017 Article 695.6(B)(1) permit the connection of jockey pump to fire pump supply conductors?

I am not questioning the supply to the jockey pump, but the supply to the fire pump. I see nothing that says you can supply it with transformer secondary conductors.
If you can supply the fire pump like that, there is nothing in 240.21 that permits the tap shown. In fact the parent text of 240.21 says:

Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

 

[hhsting]

I am not questioning the supply to the jockey pump, but the supply to the fire pump. I see nothing that says you can supply it with transformer secondary conductors.
If you can supply the fire pump like that, there is nothing in 240.21 that permits the tap shown. In fact the parent text of 240.21 says:

I have multi building campus style complex. NEC 2017 Article 695.5(C) would permit to supply fire pump from transformer. Also the jockey pump controller has ocpd.

My question was the green circled conductor in post #1 attachment which line side of fire pump controller and feeds the jockey pump controller is it tap? If not then what would you call it and is their any length associated with it like less than 10 feet etc?

 

[don_resqcapt19]

My issue is that 695.5(C) permits feeder conductors and you have transformer secondary conductors, not feeder conductors,

 

[wwhitney]

My issue is that 695.5(C) permits feeder conductors and you have transformer secondary conductors, not feeder conductors,

Transformer secondary conductors are generally feeder conductors per the definition. They just have extra requirements imposed on them by 240.21(C).

Seems like 695.5(B)'s "Secondary overcurrent protection shall not be permitted." is directly modifying 240.21.

Cheers, Wayne

 

[hhsting]

So the green circled conductor has no length limit 240.21 doesn’t apply or is part of 240.21(C) needs to be fed from transformer secondary terminal?

 

[Tyler C]

Seems like 695.5(B)'s "Secondary overcurrent protection shall not be permitted." is directly modifying 240.21.

Agreed, however after reading into it I am not sure it even matters. All the cases where the OCPD (or lack thereof) rating can exceed the conductor ampacity of 310.14/310.15 are specified in 240.4, with one of these being 240.4(E)(3), which allows for 240.21. Another common instance is "specific conductor applications" listed in table 240.4(G), with the most common such circuits I'd say being motor circuits (Article 430), and hermetic refrigerant motor-compressor circuits (Article 440). Notably, Article 695 is missing from this table, but that is likely because including it would be redundant, as fire pumps are specifically listed in 240.4(A) as a circuit where power loss creates a hazard. Since 240.4 is saying that overcurrent protection for the conductor ampacity is not necessary, I don't think the rest of 240 applies much at all.

Perhaps the answer might lie in 695.6(C), which says to treat the wiring for a fire pump tap as service conductors.

695.6 Power Wiring.
Power circuits and wiring methods shall comply with the requirements in 695.6(A) through (J), and as permitted in 230.90(A), Exception No. 4; 230.94, Exception No. 4; 240.13; 230.208; 240.4(A); and 430.31.

(C) Overload Protection.
Power circuits shall not have automatic protection against overloads. Except for protection of transformer primaries provided in 695.5(C)(2), branch-circuit and feeder conductors shall be protected against short circuit only. Where a tap is made to supply a fire pump, the wiring shall be treated as service conductors in accordance with 230.6. The applicable distance and size restrictions in 240.21 shall not apply.