General Category > Equipment and Software
Minimum Amps Required For Simple RIMS Setup
mabrungard:
A multimeter won't work. You need an amp meter to check how much load a circuit has. Some multimeters have an amp meter, but they are typically for teeny loads. The easiest way to check the loads on a circuit is to turn it off and see what was connected to it by looking for inoperative stuff.
Another thing, you said you are going to use a 1500w element? That rating is based on 240v operation, so the current loading at 120v is much lower. As pointed out above, a 4500w element operated at 120v has a much lower draw. I think my old RIMS used a 4500w low density element and I never had a problem with over-current. My new RIMS is run at 240v and all the circuitry was designed for a 50a max load. That handles 5500w and 4500w elements operating together.
Pawtucket Patriot:
I'll have to look at my multimeter to see if it even measures amps.
So would the wattage difference between running a 1500w element at 120v be proportional to the voltage difference? In other words, would running the element at 120v use a maximum 750w? If so, then I think I should be fine with using a standard 15A outlet.
mabrungard:
First, find element resistance:
Resistance = (Voltage x Voltage) / Wattage
In the case of most water heater elements, the voltage at which their power is rated is 220 to 240 volts (its usually 240v). For a 1500w element, its resistance is therefore between 32 and 38 ohms.
Second, find the current draw at the new voltage:
Current (in amps) = Voltage / Resistance
In the case of a 1500w element operating with 120v, the current is: 3.75 to 3.15 amps.
You should now see that a 1500w element is no problem for a 15a circuit. I would upsize to at least 4500w (9.4a @ 120v) and you could also go with a 5500w (11.4a @ 120v) element. They should be low or ultra-low density elements to reduce any chance at wort scorching, although scorching is unlikely if a PID is used and setup properly.
Enjoy!
Pawtucket Patriot:
Thanks a lot, Martin. This is very helpful!!
dak0415:
I would check the specs on the 1500W element. 1500W is PROBABLY a 120v element.
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