Six circuit rule

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lowvoltman

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According to table 450.3b, if you have 6 or less ocp means on the secondary of a transformer and the total rating does not exceed what would be allowed for a single ocp. than a main breaker would not be necessary. Is my understanding correct?

for instance: 30a fused switch supplying 10 kva 480-120/240 v transformer
with a small loadcenter containing 6-15a 1pole c/b.
thanks.
 
Art 450 covers the transformer installation, but you also need to comply with 408.36 if you are feeding a panel.
 
Actually, 450.3 applies to the rating of the primary device.

You need to look at 240.21(C) for protection of the secondary conductors.
 
lowvoltman said:
so 6 individually mounted breakers or fused switches would comply?
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Not for protection of a panelboard. 408.36 requires overcurrent protection of a panelboard to consist of a single overcurrent device and 408.36(B) requires that when a panelboard is supplied by a transformer that the overcurrent protection device be located on the secondary side of the transformer.

Chris
 
lowvoltman said:
so 6 individually mounted breakers or fused switches would comply?
Click to expand...

My opinion, if you complied with 240.21(C) rules on each of the taps and terminated in 6 individual breakers or fused disconnects that were grouped (per 450.3) you would be Code compliant.
(a seperate tap from the transformer to each OCP)
 
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