600v fusible disconnect

[SamC]

I have a 600v fusible disconnect rated at 30 amps. 2 questions.

1> Can I legally use this disconnect on a 240v circuit? I've seen an older version (same cat #)of this switch and it had HP ratings for 600v and 240v. The one I have has only the 600v rating.

2> Also can I use 600v rated fuses on a 240v curcuit or would I have to get 250v fuses and clips and install them in the disconnect?


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[electric-ed]

Sam, I could not find anything in the Code that addresses your specific question. I would suggest that you can use the 600 volt switch and fuses on a 240 volt circuit, but not the other way around. If you use it for a motor circuit it really should be HP rated for the voltage you are using it on.

Hope this helps.

Ed

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[SamC]

Thanks for the reply Ed.
I kind of figured the disconnect would be okay, my biggest concern was the fuses, an electrician I work with figures the fuses must also be sized to the voltage being used. Since the fusible disc. sw I have has 600v fuse clips, he figures I have to purchase 250v fuse clips and use 250v fuses. From what I remember fuses open on current flow not on wattage, so voltage should not be a factor. Iam I right on my thinking?

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[electric-ed]

Sam, you are correct, fuses open on current, not watts.
With regard to the voltage rating, 14-012 simply states that protective equipment "shall have ratings sufficient for the voltage employed". From a safety standpoint, I can't see any problem, however, you never can tell how an inspector will interpret the situation.

Ed

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[SamC]

Thanks Again Ed
Iam going to call the inspection department, and see what the inspector says. I was hoping some inspectors would be visiting this site by now. Anyway I'll post what the inspector says, regarding the fuse voltage rating.

SamC

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