Secondary Protection

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L

lady sparks lover

Senior Member
Hey Guys, it's been a while....this new job does not allow me the time to even ask questions....I'm so sorry... :oops:

I have a 150KVA transformer being fed by a 225A breaker, I know I need primary protection, and hence secondary protection, but here's my question(s)...

1. Is the secondary side considered a tap?

2. Can the secondary protection be over 25 feet?

3. Where does in say in the code I need secondary protection no matter what?

I'm at work, so can you give me answer right way? Thanks...

Miss you guys! :cry:
 
Lady,

No, they are not tap conductors. All legal possibilities are listed in (C). None of them allow more than 25' before protection except for (4).
This is what I meant by "The provisions of 240.4(B) shall not be
permitted for transformer secondary conductors." which covers "tap" conductors only and not "secondary" conductors from transformers.
 
Lady,
Welcome back!! They really are "tap" conductors" based on the definition of such in 240.2, however they must be protected per the rules in 240.21(C) and not those in 240.21(B).
As far as the application of 240.4(B), that section cannot be used anywhere that the code requires conductors to be protected at their ampacity or at a specific percentage of that ampacity. The rule in 240.4(B) does not change the conductor ampacity, it only permits the use of an oversized OCPD. The addition to the words "The provisions of 240.4(B) shall not be permitted for transformer secondary conductors" in the tap and transformer secondary conductor overcurrent protection rules was not a code change. It just made it cleared up a point that was missed by many.
Don
 
Hey Don!

It's nice to hear from you again, and all of you guys. It's my end who has not been around, sorry about that. This new job is non-stop. It's more design, then engineering, so guess what I hardly need the code book. :(

To be honest, this was my best source, and hopefully one day I'll get back into engineering.

Anyway, thanks for the answers, and you all really helped me a great deal. I promise not be way so long again.

Thanks websparky, you were a help too! :)
 
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