Feeder tap on parallel conductors

electro7

Senior Member
I am planning on a feeder tap located inbetween the main breaker and the busbar in a switchgear. The load side of the main breaker is field wired with parallel conductors. I wanted to confirm I need to run parallel conductors off the feeder taps to the line side of my fused disconnect, correct?

The main breaker and service is rated for 600A (not exactly sure the size of the parallel conductors off main breaker) and my fuses will be 300A. I am thinking 1/0 copper or 3/0 al parallel conductors to the line side of my fused disconnect from the feeder tap, does this sound right?
 

jaggedben

Senior Member
I'm assuming your feeder tap is for PV, since you put this in the PV forum.

You don't necessarily to run parallel conductors to your new disco, but you do need to tap both of the feeder conductors. All conductors of a phase should be terminated at the tap point. For example, I think you might use a Polaris type terminal block with enough positions for both existing parallel conductors, plus however many new conductors you decide upon.

You also need a new OCPD at the busbar, unless it's rated 900A.
 

electro7

Senior Member
Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

So here is what I am proposing then (thanks for reminding me).

Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?
 

ggunn

PE (Electrical), NABCEP certified
Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

So here is what I am proposing then (thanks for reminding me).

Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?
If I understand correctly what you are saying, no, not unless your busbars are rated at 600A plus 125% of your inverter Imax. Make your PV connection on the line side of the main breaker.
 

jaggedben

Senior Member
Yes, right. I will need a new OCPD inbetween the feeder tap and the busbar. It is currently a 600A service and main breaker.

So here is what I am proposing then (thanks for reminding me).

Make tap on load side of main breaker (600A) and add a 600A OCPD (maybe fused disconnect) on line side of busbar but load side of tap. That would be in conformance with NEC, correct?
I think that conforms, yes. I think ggunn isn't understanding what you're proposing. A connection on the line side of the main breaker might be a better option though.
 

ggunn

PE (Electrical), NABCEP certified
I think that conforms, yes. I think ggunn isn't understanding what you're proposing. A connection on the line side of the main breaker might be a better option though.
I got that he was proposing a load side tap with a 600A disco between the 600A OCPD and busbars of an MLO panel. That would make something approaching 1200A available to the busbars. What am I missing?
 

electro7

Senior Member
Yes. A OCPD of 600A between the tap and the busbar.

Thanks.

It would be best to do the line side tap and there are existing holes in the busbar to do so but he AHJ is asking for UL listing for it or have a UL listing engineer come do his field evaluation on it.

On another note, I wanted to confirm the NEC2017 rapid shutdown code (I am so used to Solaredge and not having to worry about anything with it). If I have these string inverters within 5ft of the array that satisfies the rapid shutdown, correct? All the inverters on this job will be located at the arrays (groundmounts). Thanks again!
 

jaggedben

Senior Member
If this install is in California then we're still on the 2014 NEC so that 5ft for rapid shutdown is fine until 2020. If on the 2017 NEC the rules change at the end of this year per special clause in the code.
 
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