# Thread: Hey Electrical Engineers 460v vs 230v 3 Phase

1. ## Hey Electrical Engineers 460v vs 230v 3 Phase

Can anyone settle an argument for me.

Whats cheaper to run? "Without" regards to startup amps. Just nominal run time.

Just for example...

25 hp compressor
45 amps at 230v 3ph
OR
22.5 amps at 460v 3ph

My beef is, they consume the same power! but its a ongoing argument and no one really knows?

2. Originally Posted by 94blowncobra
Can anyone settle an argument for me.

Whats cheaper to run? "Without" regards to startup amps. Just nominal run time.

Just for example...

25 hp compressor
45 amps at 230v 3ph
OR
22.5 amps at 460v 3ph

My beef is, they consume the same power! but its a ongoing argument and no one really knows?
My vote is it's a wash. Unless the electric co. gives a better rate for the higher voltage.

3. 460 volt consumes less current, less cost to operate.

4. Originally Posted by Peztoy
460 volt consumes less current, less cost to operate.
Well........

Thats the argument. Mathmatically they equal the same wattage...right?

5. But using Ohm's law, wouldn't the wattage be the same and that's what you are paying for?

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What is the line voltage supplying the transformer? The difference will be the the losses in transforming the incoming to the correct voltage into the unit. In our plant we have 13.8 with large efficient transformer that goes to 480. step down again and you have more losses therefor in our plant 480 is less cost to operate.

7. Originally Posted by drjfjr
What is the line voltage supplying the transformer? The difference will be the the losses in transforming the incoming to the correct voltage into the unit. In our plant we have 13.8 with large efficient transformer that goes to 480. step down again and you have more losses therefor in our plant 480 is less cost to operate.
What if the service is 480 or 240 and no step downs ?

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kw=kw if no losses in transmission then no difference in efficiency

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thats a small motor, but for larger motors, look at the difference in cost for conductors, conduit, and installation. on larger loads, it can be a lot.

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Higher the voltage the lower the amps. Let's say we have a motor running at 110v and 8 amps. If you run 220v to that same motor the amps will be cut in half (4amps). Your electric bill is in kW. Therefore, you would see no cost difference between the two voltages. 220v requires 1/2 the time to do what a 110v circuit does.

watts=volts(amps)

Now, the difference in cost of wiring and components... 220v will cost more as you need two 110v legs. So 220v circuits will costs 2x (or more depending on gauge) as much to install compared to a 110v circuit.

Say you had a 110v hot tub and a 220v hot tub. The 220v hot tub will heat up 2x faster than the 110v but use the same amount of energy. As for motors it won't matter as the RPM's will remain the same.

As everyone is stating if their is losses in transmission then you will see a fraction of savings but nothing worth noting
Last edited by ZeroTolerance; 03-02-2011 at 11:50 PM.

11. If I remember... in the OP's question; we were comparing 460 3ph to 230 3ph...

IMO the KWH will be the same, so the cost to operate theoretically will be the same. Some power co's may offer different rates for different services... talk to the power co.

The difference is the circuit to the unit... If the 230V unit uses 45A, then it needs 6 GA wire... If the 460V unit uses 22.5A then it needs 10GA wire... And we both know the cost difference on those two cables. Lets not forget larger conduit, larger disconnect, and larger breaker.

The major advantage to higher voltage is less expense in the supply circuit. Not much on one unit... but on the roof of a Walmart, and you may save a significant amount to Sparky.

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Yes, we were.... I was just comparing apples with apples as the difference in 110 and 220 is the same as 230 and 460.

Would you like me to change the voltage values in my post to appease you?

Also, gauge size is determined by length of run btw. So, your post above is somewhat inaccurate

13. Originally Posted by ZeroTolerance
Yes, we were.... I was just comparing apples with apples as the difference in 110 and 220 is the same as 230 and 460.

Would you like me to change the voltage values in my post to appease you?

Also, gauge size is determined by length of run btw. So, your post above is somewhat inaccurate
Hmmm,

Somehow I do not remember quoting anyone in my post... sorry if it sounded personal... it was not meant to be.

The point was to compare 3Ph to 3ph at different voltages.

As to the wire size... both examples have lots of room (length) in them...

However just for the record: Tell me the max ft of 10GA wire on 22.5A and the max ft of 6GA wire on 45A... that way we both can be right...

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