430.36 and 430.37

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Isaiah

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I have a very old combination starter (1950's?) that has only two overload devices installed in phases A and C. The starter is using a 3-phase fused switch (vs MCP) for motor branch protection. The fuses are for short circuit only. Is this a violation of 430.36?
 
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jap

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It would seem that you do in fact have a fuse installed in each ungrounded conductor, but, they are not being used for the overload protection.

The 2 overloads in the starter are serving that purpose.

If 1 or the other Overloads amperage gets exceeded it will trip out the entire overload and disconnect the motor, or, at least it should.


JAP>
 
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jap

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Though you may need to look at 430.7 and it's table to see if you have enough overloads in place to serve the purpose.


JAP>
 
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Isaiah

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jap said:
Though you may need to look at 430.7 and it's table to see if you have enough overloads in place to serve the purpose.


JAP>
Click to expand...


I've done a little more research; it seems prior to 1971 NEC, two overloads were acceptable. Since then, a concern over 'single-phasing' has led to requirement of OL's in each phase.
 
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