Line voltage question

[Mitchell Andrus]

I'm setting up the new shop and tested the line voltage for the first time. I'm getting 122.1 VAC & 243.8 VAC on average (fluctuates a few tenths).

Seems high - is this a problem for my motors in the shop?

I'm getting the same readings at the house and nothing seems to be having a problem there.... Heat pump, hot tub motors....
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[Mike Minto]

can i stealth a question onto yours? not knowing anything about electricity, is the kind of thing you are asking about (line voltage) something that would vary with the length of the electric wire feeding one's shop? would a multi-meter be what one would use to check this?

[Dan Friedrichs]

You're fine - the voltage will fluctuate +/- 10% or more. I have 130V at my house. The motors won't mind at all.

Mike - the line length only matters when you have a load attached, because the voltage dropped is current*wire_resistance. If you don't have any current flowing, you won't lose any voltage. You might have 125V with just a multimeter attached (which draws almost zero current), but if you hook up a large appliance and the multimeter at the same time, you could have significantly less voltage (you could lose 10V or more).

[Rod Sheridan]

Dan, I don't think you meant to indicate that voltage drop is proportional to the square of the current, it's proportional to the current.

Regards, Rod.

P.S. Mitch, the voltage is perfect, modern value is 120/240V so you're right on the correct value.

[Dan Friedrichs]

Dan, I don't think you meant to indicate that voltage drop is proportional to the square of the current, it's proportional to the current.


d'oh! Thanks, Rod...

[Lee Schierer]

I routinely have 125 to 128 volts at my house. Basically you are getting a free bit of power at the slightly elevated voltage. It won't hurt your motors at all.

[Mitchell Andrus]

Thanks, all.

Our here in the country.... some guy on a treadmill......

I have a comm'l building in NJ. A potential tenant passed on the space due to the volts being too low for a few of his bigger machines. Power Co. said it was within limits, his electrician said no-go.

Ya never know.
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[Ed Griner]

Mitch, Maybe your potential tenant wanted 480 volts.Did you mention the tritium in the ground water? Just kidding!!! Ed

[Van Huskey]

Thanks, all.

Our here in the country.... some guy on a treadmill......

I have a comm'l building in NJ. A potential tenant passed on the space due to the volts being too low for a few of his bigger machines. Power Co. said it was within limits, his electrician said no-go.

Ya never know.
.

Low line voltage is much more of an issue than high, well in that you will rarely see anything above 130 give or take a volt or two but you can often really pull down voltage in lots of ways and though either outside a tolerance level (which id different for different types of equpment) can cause damage. FYI I normally see 125-126V.

[David Helm]

Generally what most Americans call 220 is actually 240 + or -. 110 is actually 120 + or -.

[David Cefai]

It might be a good idea to watch the voltage behaviour when you start up a machine. It should dip momentarily and then return to more or less the previous value. If it doesn't then your line has too high a resistance and may warm up.

I can't quote numbers as over here we use 220 / 415 V.

[Mitchell Andrus]

I can't quote numbers as over here we use 220 / 415 V.

Set up your profile so we can tell where "here" is. It's interesting to know where our members are.
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[Rod Sheridan]

Set up your profile so we can tell where "here" is. It's interesting to know where our members are.
.

Somewhere where they have 50Hz power:D..............Rod.

Regards, Rod.

[Brian Cover]

can i stealth a question onto yours? not knowing anything about electricity, is the kind of thing you are asking about (line voltage) something that would vary with the length of the electric wire feeding one's shop? would a multi-meter be what one would use to check this?

Yes, the voltage under load (measured when the motors are running under load) will always be affected by the length of the wire. Longer runs require fatter wires.

Go to Home Depot and get "Ugly's" Electrical reference for about $9. It is a pocket guide that answers all your questions to do it right the first time.

When in doubt, upsize the wire one gauge.