Amps from 120v element on 240v circuit

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scottland

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I couldn't find the answer to this anywhere, and I wanted to double check.

I'm planning an electric system right now. I'm going to be running off of a 50a Range circuit. I have a 4500w 240v element, which I know will draw a max of 18.75a.

I also have a 1500w 120v element I use in my HERMS HEX. I'm planning on running it off of one of the Hot legs from the 240 circuit. Will this draw 6.25amps (1500/240) or 12.5amps (1500/120). I believe it's the later (12.5a), but I wanted to double check. I'd rather plan for my system to be under 30a total, and keep the wiring at 10gauge rather than 6 or 8. So I'll ditch the 1500/120 element for a 1500/240 element if it draws 12.5a off of the single hot leg.
 

crane

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You are correct the 120V 1500W element will draw twice the current (12.5A) compared to a 240V 1500W element (6.25A). The 120V element will have half the resistance of a 240V element of the same wattage.
 
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scottland

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Thanks. I'll swap it out for a 1500/240 element to comfortably stay under 30a.

One more question. I'm using a 50a range outlet, which i'm connecting a 50a Spa Panel (50a GFCI Breaker) to. Now my system is going to be under 30a, so I'd rather use 10gauge wire inside my control panel. Do I need a 30a breaker or 30a fuse to protect that 10g wire?
 
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