used voltage tester and part of it melted

**sawmilleng** · 03-01-2015, 01:35 PM

Just a slight correction here...

Voltages are not absolute...for example, the common industrial voltage is called 460, or 480, or if you are a little older it sometimes is referred to as 440. All the same animal. If you put a voltmeter onto it you would see anything in the range, mostly +/-10% around 460..., but some utilities shoot for 480.

In one of the plants I engineered for when everything was down you would see just over 500V and when we were putting out rivers of lumber and drawing lots of power the voltage would suck down to 415V. This was due to an undersized main transformer and lack of an automated gizmo on the transformer called an "auto load tapchanger" that would change taps to boost the voltage when under load and lower it when idling.

I ultimately changed out the transformer for a bigger, good used one from a US Air Force base in California that had a tapchanger. We set the voltage at 480 because the higher voltage meant motors drew less current to give the horsepower.

Just the same in home plug voltages. You've heard 110, 117, 120, even 130 V for a standard plugin voltage. Its all the same. The older guys have heard 110 a lot more than they have now, where 120 has become the "standard". The exact voltage you see in you house is governed by the settings on the transformer on the pole out on the street and the load on the transformer.

Jon. ...the details geek....

**mthomasdev** · 03-01-2015, 03:54 PM

Originally Posted by sawmilleng

Just a slight correction here...

Voltages are not absolute...for example, the common industrial voltage is called 460, or 480, or if you are a little older it sometimes is referred to as 440. All the same animal. If you put a voltmeter onto it you would see anything in the range, mostly +/-10% around 460..., but some utilities shoot for 480.

In one of the plants I engineered for when everything was down you would see just over 500V and when we were putting out rivers of lumber and drawing lots of power the voltage would suck down to 415V. This was due to an undersized main transformer and lack of an automated gizmo on the transformer called an "auto load tapchanger" that would change taps to boost the voltage when under load and lower it when idling.

I ultimately changed out the transformer for a bigger, good used one from a US Air Force base in California that had a tapchanger. We set the voltage at 480 because the higher voltage meant motors drew less current to give the horsepower.

Just the same in home plug voltages. You've heard 110, 117, 120, even 130 V for a standard plugin voltage. Its all the same. The older guys have heard 110 a lot more than they have now, where 120 has become the "standard". The exact voltage you see in you house is governed by the settings on the transformer on the pole out on the street and the load on the transformer.

Jon. ...the details geek....

Jon,

I'm not trying to turn this into an argument, just going to provide the links that I have available to back up my previous post:

https://www.crmagnetics.com/Portals/...d-voltages.pdf

North American Voltage

As one of them indicate, utilities strive for plus or minus 5% of the various voltages available (120, 208, 240, 277 & 480)This is important because machinery does not run effiecently on voltages that deviate to much. To back up that statement, NEC requires that circuits be designed for limited voltage losses. I believe it is 3% for branch circuits and 2% for feeder circuits.