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Old 07-01-2019, 08:09 AM   #1
The Real BigGuy
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My 240 volt water heater’s connected to an old style pull handle box with 2 screw in fuses, both 30 amp. The connection at the heater is 2 wire with an additional ground.

I rarely work with 240. My question is, do the 2 30 amp fuses effectively make this a 60 amp circuit? It should only be a 30 amp so I want to reduce the fuse size if necessary.


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Old 07-01-2019, 08:27 AM   #2
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30 on each leg. what you have is fine as long as the wire is at least #10.
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Old 07-01-2019, 11:02 AM   #3
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Quote:
Originally Posted by The Real BigGuy View Post
My 240 volt water heater’s connected to an old style pull handle box with 2 screw in fuses, both 30 amp. The connection at the heater is 2 wire with an additional ground.

I rarely work with 240. My question is, do the 2 30 amp fuses effectively make this a 60 amp circuit? It should only be a 30 amp so I want to reduce the fuse size if necessary.


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You may have a 60 amp service, but the circuit is 30 amp. No need to reduce anything. As was said by the earlier post, just make sure you have a minimum 10 wire to water heater.
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Old 07-01-2019, 08:18 PM   #4
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Thanks for clearing that up. Forgot about “legs”. The wire size isn’t an issue and It is a 100 amp service. Feel better now.


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Old 07-03-2019, 01:06 PM   #5
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a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.
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Old 07-03-2019, 01:27 PM   #6
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Quote:
Originally Posted by SIKSUKR View Post
a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.


umm its Amps...
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Old 07-03-2019, 01:36 PM   #7
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Quote:
Originally Posted by SIKSUKR View Post
a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.
In this case, it's "worth" very little.
That comment is a tad confusing.
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Old 07-03-2019, 02:51 PM   #8
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Old 07-03-2019, 03:53 PM   #9
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Quote:
Originally Posted by SIKSUKR View Post
a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.
Or a different explanation...

240V X 30A = 7200 watts
120V X 60A = 7200 watts

most water heaters consume between 4500 and 5500 watts....

going back the other way with that piece of information you see that if all is good in the world, of your 60 or 30 Amp circuit you are really only using

5500 W / 240V = 22.9 AMPs
5500 W / 120V = 45.8 AMPs

on the lower side we have

4500W / 240V = 18.75 AMPs
4500W / 120V = 37.5 AMPs

so there... now it should be less confussing....
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Old 07-03-2019, 06:49 PM   #10
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Thank you! Ohm’s law


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