Switch for a hot water tank

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  #1  
Old 09-11-07, 12:01 PM
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Switch for a hot water tank

I want to add a switch to my 30 amp 240 volt hot water tank at my cottage, so I can turn it off and on without pulling the double fuse in the main box. I purchased a 30 amp DPST switch box made by Federal Pioneer. It includes places for 2 screws-in fuses, the little guys, not the larger cartridge type. I need 2 30 amp fuses, right? However the fuses are only rated for 120 volt. Is this OK? The switch box includes bars for the neutral (which I will not use), and ground.

So back to my question, are the 30amp 120 volts fuses ok to use in this 240 volt only application? I am not familiar with fuses. I know about breakers.

I am not really explaining this too well.
 
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  #2  
Old 09-11-07, 12:11 PM
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Each of the two hot wires in a (North American) 240 volt setup is only 120 volts. They are 120 volts with respect to ground and exactly out of phase so they are 240 volts with respect to each other.
 
  #3  
Old 09-11-07, 12:22 PM
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Thanks

That's what I thought, but it's good to double check. Somehow not having the neutral connected confused me. I would not even give it a second thought if it had been a 3 wire circuit including two hots and the neutral; that I understand. However, the tank is a two wire 240 volt only unit, so I wanted to double check.

I really wanted to install a timer for the water tank, but I can't find one here in Canada. I only use the cottage at weekends, so I need a timer with settings for each day, on Friday, off Sunday. I was hoping to buy the Intermatic EH40, but it does not appear to be available here in Ontario.

Thanks for your help.
 
  #4  
Old 09-11-07, 01:48 PM
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it might be legal, but..

I really don't like edison base fuses for 240v circuits. If the box allows you access to the fuses with the power on, unscrewing the fuse exposes the operator to line votage via the shell of the fuse. Also, edison base fuses do get warm when delivering 20+ amps for a period of time.
Can't you get an unfused disconnect? Safer, cleaner, more reliable...
 
  #5  
Old 09-11-07, 01:58 PM
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Personally, I would install a timer and use that.
 
  #6  
Old 09-11-07, 04:23 PM
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I agree. I don't like using the switch box with fuses. But it was the only thing available from the Orange big box store. (Why do they still make things with the old fuses anyway?)

I will look around for a disconnect box.

Thanks for the help.
 
  #7  
Old 09-11-07, 05:16 PM
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Try an electrical supply store.

And I know the big box stores sell timers.
 
  #8  
Old 09-11-07, 06:47 PM
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The big box stores do sell 250Volt 30A disconnect swithes.
No need for fused devices.

For this application I would think a timer not feasible. It would need to be a seven day 24 hr or astronomical style model, not cheap.
 
  #9  
Old 09-11-07, 09:30 PM
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At Home Depot or Lowe's ask for an un-fused AC disconnect switch. It may be easier to find a 60 amp rated one and that would be fine.
 
  #10  
Old 09-17-07, 06:36 PM
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Thanks

Returned the switch, and got a 60 amp disconnect.

Works great. Thanks for all your help.
 
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