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-   -   fused disconnect and/or GFCI ? (http://www.diychatroom.com/f18/fused-disconnect-gfci-14587/)

pchiz 12-19-2007 11:13 AM

fused disconnect and/or GFCI ?
 
I am installing a hard-wired/plumbed residential steam humidifier which requires 240v (no neutral) and is rated at 17.8 Amps. The manual calls for "an external fused disconnect" rated at 25 amps but does not mention a GFCI breaker. It seems like a gfci would make sense in this case, and may be required by NEC (but not sure how a humidifier gets classified by NEC).

My question is how "best" (compliant with NEC and safest way) to do this ---

a) install 30 amp GFCI breaker in main panel (SquareD QO panel -- no 25amp breakers available) and a 25 amp fused disconnect at the unit. (or can I use non-fused disconnect since using GFCI at main panel?)

b) install 30 amp breaker in main panel and a 30 amp GFCI breaker/disconnect at the unit (25 amp if i can find one)

c) install 30 amp breaker in main panel and 25 amp fused disconnect at the unit, and skip the GFCI...


Thanks!!

220/221 12-19-2007 11:45 AM

"c"



Does your water heater require a gfci?

Dishwasher?

Pool motor?

Maybe they should, but they don't.

Of course it's always OK do go the extra step. I don't see how it would HURT to instal the GFCI as long as there is no control circuitry one one leg.

HouseHelper 12-19-2007 11:55 AM

"c"
That's two votes for "c"

NateHanson 12-19-2007 11:56 AM

You can probably use the breaker for the disconnect if it's within sight of the installed humidifier. Not sure if it also has to be a certain distance?

goose134 12-19-2007 09:04 PM

Also bear in mind that a GFCI device does not measure current to ground. It measures a differential in the current on the neutral. Having no neutral will greatly hamper the operation of the device.:) The others are right, no GFCI is required.

goose134 12-19-2007 09:06 PM

Sorry. As for the disconnect, I believe that the breaker will qualify if within sight. If not, the small fused disconnect that you will need are not expensive at all, and readily available at many home centers and supply houses.

HouseHelper 12-19-2007 09:12 PM

Quote:

Originally Posted by goose134 (Post 81960)
Also bear in mind that a GFCI device does not measure current to ground. It measures a differential in the current on the neutral. Having no neutral will greatly hamper the operation of the device.:) The others are right, no GFCI is required.

A 240V GFCI measures the current balance between the two hots; the protected circuit does not need a neutral. The GFCI itself does... that's what the white pigtail provides.

goose134 12-20-2007 10:04 PM

Yes, that makes sense. Kirchoff's Law strikes again!:)

RichyL 12-21-2007 10:02 AM

When in doubt always go with the manufacturers specs. If something asks for a fused disconnect, generally you should always go with a fused disconnect. My vote is for "C"


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