3 phase power 240v vs. 480v
I have what I hope is a minor problem.
I am building an irrigation system, which has four pumps, a motor to drive a debris screen, and associated underground wiring.
The Power Coop showed up yesterday to energize, and we found out they deliver 480V, and not 230V 3-phase we designed and built for.
I know that all the motors need to rewired, for the 480V, and that all the direct buried conductor is now twice as big as it needs to be.
The question I have is; do the breakers all need to be down sized by half?
I know that electrical sub, and the electrical engineer will tell me sometime in the next day or so, but I want to get a handle on the dollars as soon as I can so I can start figuring out how much this should cost.
Replies
In general, yes, the breakers will need to be downsized by about half. You also need to be sure that all the panels and wiring are rated for 480V.
An option to consider is a transformer. 480/240 transformers are a fairly common item and may work out cheaper than redoing everything else, especially if you'd have to change out some motors.
Luckily, all the motors are dual voltage, so the electrician will only have to rewire them at the motor.
Wasn't sure on the breakers, my gut feeling was they would to be downsized by half.
There are three motors, that we haven't touched, so if we went with the transformer we would have to rewire them, so it won't be much more time to rewire the four we installed, than to rewire the three.
More important the overloads in the motor start will need to be resized. They are what are closing matched to the motor currernt.
Breakers can be several times the motor current as they are only used for protecting the wiring.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
You may be able to keep the breakers and panel(s) if there are rated at 480v. You can install fused disconnects at the moters with the proper fueses to get the proper overcourent protection; just make sure they are also rated and 480v or over.