PV Site Transformer Secondary Conductors, 240.21(C)(1)-(6)

[cyriousn]

We've been asked to perform some studies work on a PV site that was designed by another firm. It's a 2MW site with a 13.2kV/600V 2MVA transformer. On the secondary side of the transformer the conductors are going to (4) 800A panelboards and an auxillary power transformer with a 60A fused disconnect.

I'm trying to determine if 240.21(C) would apply to this scenario since it's a PV site.
240.21(C)(1) does not appear to apply since the transformer is Yg-Yg.
240.21(C)(2) does not appear to apply since the secondary cables are over 10 feet long.
240.21(C)(3) does not appear to apply since this is not an industrial application and the feeders terminate into panelboards.
240.21(C)(4) does not appear to apply since the secondary feeders never go inside a building. Everything is outside. Am I interpreting this section correctly or would all outdoor conductors fall under this section?
240.21(C)(5) does not appear to apply since the primary and secondary combined is over 25 feet.
240.21(C)(6) does not appear to apply and the secondary cables are over 25 feet long and the feeder going to the Aux transformer would be too small to meet the voltage ratio * Primary protection value *1/3.

At this point I'm thinking I'm interpreting 240.21(C)(4) incorrectly, I'm looking at the totally wrong code section, or I need to give the owners a heads up. Thanks in advance to any input on this one.

 

[jaggedben]

I think 240.21(C)(4) applies.

 

[electrofelon]

Sorry of this is obvious, but is this definitely a customer owned transformer and they take service at 13.2 KV with a 13.2 KV service disconnect?

 

[Carultch]

At this point I'm thinking I'm interpreting 240.21(C)(4) incorrectly, I'm looking at the totally wrong code section, or I need to give the owners a heads up. Thanks in advance to any input on this one.

If everything is outside, and never on or in a building, the outside unlimited length rule applies, both for taps and transformer secondarys (assuming a customer-owned transformer, as opposed to utility-owned transformer).

 

[cyriousn]

Sorry of this is obvious, but is this definitely a customer owned transformer and they take service at 13.2 KV with a 13.2 KV service disconnect?

Sorry of this is obvious, but is this definitely a customer owned transformer and they take service at 13.2 KV with a 13.2 KV service disconnect?

Yes 13.2kV at the street with a fused GOAB on the high side of the transformer.

 

[cyriousn]

If everything is outside, and never on or in a building, the outside unlimited length rule applies, both for taps and transformer secondarys (assuming a customer-owned transformer, as opposed to utility-owned transformer).

Thanks, yes this will be a customer owned transformer and everything will be outside, never on or in a building.

 

[electrofelon]

240.21(C)(4) does not appear to apply since the secondary feeders never go inside a building. Everything is outside. Am I interpreting this section correctly or would all outdoor conductors fall under this section?

They don't have to go inside a building for the point of load termination, they just are allowed to.

Thanks, yes this will be a customer owned transformer and everything will be outside, never on or in a building.

So if this is a customer-owned transformer, then I agree with the others, covered by (C)(4)