fused disconnect and/or GFCI ?

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Old 12-19-07, 02:05 AM
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Question 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" 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...


Also, if i use a fused disconnect, which is preferred -- the lever switched type of disconnect or a pull-out type disconnect?

Thanks!!
 
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Old 12-19-07, 06:01 AM
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I've never seen a GFCI on a humidifier circuit. The type of disconnect is your personal preference. I prefer the lever type but there is not a thing in the world wrong with using a pull out type.
 
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Old 12-19-07, 06:17 AM
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2 pole 30 amp breaker in panel
10 gauge wire

240 vac 30 amp cartridge fused disconnect with 25amp fuses install
 
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Old 12-19-07, 09:55 AM
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Wow, I'm really surprised that a gfci is not required or highly recommended for a standalone steam humidifier.

Is there any reason, besides extra cost, not to put a gfci breaker in main panel and have fused disconnect at unit?
 
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Old 12-19-07, 04:30 PM
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Originally Posted by pchiz View Post
Wow, I'm really surprised that a gfci is not required or highly recommended for a standalone steam humidifier.

Is there any reason, besides extra cost, not to put a gfci breaker in main panel and have fused disconnect at unit?

Nope. Just the fact your throwing your money away. Code doesn't require it. The manufacture doesn't either. I'm not sure if it will do you any good because all the GFCI breakers I have installed for spas require a neutral. Your humidifier does not use a neutral so the GFCI breaker may not work properly anyway.
 
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Old 12-19-07, 04:49 PM
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A 240 volt GFCI has to determine the current on all three wires (2 hots and a neutral). It works fine on both 240 volts and on 120/240 volt circuits.
 
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Old 12-19-07, 10:04 PM
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Originally Posted by Tolyn Ironhand View Post
I'm not sure if it will do you any good because all the GFCI breakers I have installed for spas require a neutral. Your humidifier does not use a neutral so the GFCI breaker may not work properly anyway.

GFCI can be used for loads with no neutral - they would still sense a current imbalance on the two lines, as well as shorts, etc. There are plenty of spas that require no neutral (because they use only 240v, not 120v& 240v) yet those still require and benefit from a GFCI.
 
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Old 12-20-07, 12:26 AM
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Originally Posted by Tolyn Ironhand View Post
Nope. Just the fact your throwing your money away. Code doesn't require it. The manufacture doesn't either.
Yea, and it's still legal to drive an old car with no airbags, but i don't do that anymore either... I think spending an extra ~$100 for GFCI when dealing with a water-fed appliance isn't such a bad investment.
 
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