4500W element 240V v 220V (easy question)

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ekjohns

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I am making a eBIAB system with 1 PID and 1 4500W element. At 240V this should pull 18.75A. I will be moving soon and plan to use the dryer plug and Spa panel so i think there is a chance it could be 220V which means 20.5A. However I think I read somewhere that the resistance of the elements is static so a 4500W element on 220V will run slightly under 4000W (18.2A). Is this correct? I want to use 20A plugs to save on cost and 4500W should be more than enough power for my 5 gal batches.
 
you are correct. However, saying "220" is really a misnomer. I believe 220 service is minimum voltage for service to a residence, so you are likely to have ~240.
 
The load is as you've stated 4500 watts:

4500w/240v=18.75 amps

The NEC considers a HWH a continuous load therefore the circuit must be sized at 125% of the nameplate value:

18.75 amps * 125% = 23.4 amps.

Per code, you really shouldn't go over 3500 watts on a 20 amp breaker and 12gauge wire. Just be aware that your pushing it with that 4500 watt heater.
 
I was actually thinking last night I might go with a 3500W element anyway which will be 14.6A + 1.4A for my pump will give me 16A. Will that be okay with 20A receptacles and 12 gauge wire? If I do the 124% rule that puts me at 20A which should be right at the max since that is only a theoretical load correct?
 
I'm not an electrician, but 16 amps is the rating for continous load, which I think is 3 hrs at full blast. A 3500 watt heater should boil 5 gallon batches just fine, and if the name plate on the pump says 1.4 amps at 240v, all should be fine. I doubt the pump starting current, even with the heater at full blast, would be enough to trip the breaker as its a short duration.
 
The load is as you've stated 4500 watts:

4500w/240v=18.75 amps

The NEC considers a HWH a continuous load therefore the circuit must be sized at 125% of the nameplate value:

18.75 amps * 125% = 23.4 amps.

Per code, you really shouldn't go over 3500 watts on a 20 amp breaker and 12gauge wire. Just be aware that your pushing it with that 4500 watt heater.

12ga solid core shouldn't have anything over 20amp on it. But stranded could possibly handle more. It's all about surface area :)

... well if you were planning on using 12ga stranded on a 30amp circuit to power a 4500w element.
 
#12awg thhn wire either solid or stranded is rated for 30amps at 90deg C. But the nec says not to use #12 for more than 20a. part of the reason for this is that the terminals you connect the wires to are only rated for 60deg C. therefore you would have to derate the wire to the minimum terminal rating or 20a on 12awg wire.
 
#10awg at 90° C. is 35A. if you open a water heater you'll often see #12 awg solid wire. that wire has a different type of insulation than what is commonly available. I believe it is rated for 105°C. either way they full under th UL regs rather than the nec.
 
My roofing welder (for single ply) has a voltage gauge. Often reads 250 and can drop below 220 when heated up. The voltage drop comes from the resistance in the wires all the way from the service transformer. That thing does not even pull 20 amps but I use 50 foot of 8 AWG and 150 foot of 10 AWG from the job site temporary service. You will get more power out of your element if you over size your wire.
 
So as a general consensus if I use a 3500W element on 240V with a march pump running at 120V (wired from the 240V source) with 20A rated plugs and 12AWG I should be okay?
 
grandequeso said:
#12awg thhn wire either solid or stranded is rated for 30amps at 90deg C. But the nec says not to use #12 for more than 20a. part of the reason for this is that the terminals you connect the wires to are only rated for 60deg C. therefore you would have to derate the wire to the minimum terminal rating or 20a on 12awg wire.

So use the 30a recepticles and plugs and go w the cheaper 12/3 for wire :)
 
I would recommend keeping everything standard. if you're doing 20a keep it all 20a. Heck if you're going through the trouble running a new circuit just bite the bullet spend an extra few bucks and run it 30a. I can't stand waiting on my hlt to heat or my boil to get rolling. I couldn't stand using less than 5500 watts
 
I was thinking about 5500W but will have to check an make sure the wall wiring can handle that, but for the sake of purchasing I might be better to just drop the coin and not have to re-buy stuff if I ever want to move to a higher powered element
 
Right, 240VAC is typically the nominal supply voltage. Appliances or devices are often rated at 220VAC to allow for voltage drop in the wiring.

Heating elements are purely resistive, and their resistance does not change based on the supply voltage, so running any resistive heating element on a different voltage would give:

V1 = rated voltage, i.e. 240VAC
V2 = supplied voltage, i.e. 220VAC

Then the actual output as a ratio is ratio of the voltages squared, like

Power output percentage = (V1/V2)^2

So for example, (220 VAC supplied / 240 VAC rated) squared is 84%. So a 5000 watt resistive heater rated at 240VAC would give 84% of that or 4200 watts at 220VAC.
 
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