Electrical Question

The Real BigGuy · 07-01-2019, 07:09 AM

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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jbolty · 07-01-2019, 07:27 AM

30 on each leg. what you have is fine as long as the wire is at least #10.

swnoel · 07-01-2019, 10:02 AM

Quote:

Originally Posted by The Real BigGuy

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.

The Real BigGuy · 07-01-2019, 07:18 PM

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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SIKSUKR · 07-03-2019, 12:06 PM

a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.

SteveO123 · 07-03-2019, 12:27 PM

Quote:

Originally Posted by SIKSUKR

a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw.

umm its Amps...

brk-lnt · 07-03-2019, 12:36 PM

Quote:

Originally Posted by SIKSUKR

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.

jbolty · 07-03-2019, 01:51 PM

…………………. …………..

LIforrelaxin · 07-03-2019, 02:53 PM

Quote:

Originally Posted by SIKSUKR

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....

The Real BigGuy · 07-03-2019, 05:49 PM

Thank you! Ohm’s law

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07-03-2019, 12:06 PM	#5
SIKSUKR Senior Member Join Date: Apr 2004 Posts: 5,075 Thanks: 215 Thanked 903 Times in 509 Posts	a 240 30 volt circuit would draw the same as 60 volts of 120 fwiw. __________________ SIKSUKR

07-03-2019, 01:51 PM	#8
jbolty Senior Member Join Date: Jun 2015 Posts: 664 Thanks: 320 Thanked 251 Times in 150 Posts	…………………. ………….. Attached Images

07-01-2019, 07:09 AM	#1
The Real BigGuy Senior Member Join Date: Apr 2004 Posts: 1,308 Thanks: 125 Thanked 472 Times in 287 Posts	Electrical Question 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. Sent from my iPhone using Winnipesaukee Forum mobile app

07-01-2019, 07:27 AM	#2
jbolty Senior Member Join Date: Jun 2015 Posts: 664 Thanks: 320 Thanked 251 Times in 150 Posts	30 on each leg. what you have is fine as long as the wire is at least #10.

07-01-2019, 07:18 PM	#4
The Real BigGuy Senior Member Join Date: Apr 2004 Posts: 1,308 Thanks: 125 Thanked 472 Times in 287 Posts	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. Sent from my iPhone using Winnipesaukee Forum mobile app

The Following User Says Thank You to jbolty For This Useful Post:
Electric man (07-05-2019)

07-03-2019, 05:49 PM	#10
The Real BigGuy Senior Member Join Date: Apr 2004 Posts: 1,308 Thanks: 125 Thanked 472 Times in 287 Posts	Thank you! Ohm’s law Sent from my iPhone using Winnipesaukee Forum mobile app