Electrical Repair Questions? Ask an Electrician for Answers ASAP
Hello. Welcome to Just Answer.
This calculates to about 36 amps.
That being the case, I would feed it with a 50 amp breaker, and #6 copper wire.
If you are using THHN stranded building wire, it can be #8/
can you provide the formula that you used
Sure. Volts X Amps = Watts. We know the wattage is 7500, and the voltage is 208. So, just divide the watts by the volts, 7500/208 to arrive at 36 amps.
watts divided by volts--x 1.732 equals amps correct ??this is 3 phase
are u there
Thank you for your patience. I'm referencing my materials, as it's been a while since I had to determine when to use the 1.73 rule.
Yes, you are correct. I was mistaken. 36 X 1.73 = 62.28. That would be a 70 amp breaker and #4 copper wire.
7500 watts at 240 volt SINGLE phase is 31.25 amps (watts divided by volts)---7500 watts / 208 volts=36.06 times 1.732 is= 62.46 amps----shouldn't the amperage on 3 phase be lower than single phase ???
Now that I look at it again, I believe we are both misapplying the formula.
what am i doing wrong ?
We don't need to multiply the original amperage I arrived at by 1.73.
That is to find watts.
Wire is sized on amperage, not wattage.
a 7.5 kw heater at 208 3 phase
7.5 is 7500 watts
so only 7500 divided by 208 ??
I apologize for being rusty, it's been a while since I've had to use the 1.73 rule.
gues im done--nite
If you don't mind standing by for a moment...
I just found a site that explains it very well.
so i just close this web site now ?
I'll post a link after I view it.
ok--go i go now ?? dinner is waiting
You can go and come back later. No problem.