Class 450.3 (A) = OVER 600 Volts...
So forget it. That's industrial territory.
Class 450.3 (B) = LESS THAN 600 Volts...
This is the category for dry-type transformers we all know and love.
Class 450.3 (C) = Voltage Transformers...
Which is what you've described it as.
EITHER WAY you're required to provide OCPDs...
See 408.52: "...is protected by standard overcurrent devices rated 15 amperes or less."
So, you don't get to pick a rating out of the air.
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BTW, I don't think that your transformers are 450.3(C) Voltage Transformers. I'll bet that they are a part of some low voltage lighting set-up.
That makes them 450.3(B) transformers, in my eyes.
Why? They're not switchboard devices with potential coils, pilot lights, etc.
They're power supplies for some low voltage loads. -- Hence 450.3(B).
Last edited by Tesla; 05/23/12 06:10 PM.
