138 Volts!?

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I just signed a lease on a nice warehouse in the industrial part of town...mostly just for my own work shop. I measured the voltage of my outlets, mostly to check for 220v. But when I tested my regular "110 volt" outlets, they read 138 volts! I know 110 isn't supposed to be an exact number, but 138 seems awful high! They're always 119v at my house. Is this a problem I need to fix? I don't want to burn out anything expensive just by plugging it in...
 
If you are close to the supply transformer, your volts will be high (is).

Our 415 volt boards at the power station are usually 435-440.

As to burning things out, AC motors draw less current when running higher volts.
 
Crinkles, they have different frequencies as well.

Oz uses 50 Hz (my generators run at 3,000RPM), other places use 60Hz (3600 RPM for full speed machines).

Three phase is 415 volts (phase to phase), while phase to earth is 240.
 
IIRC, the fed regulates the frequency (60hz), there are fines and such if that isn't spot on. voltage is allowed to fluctuate though; that's why some call it 110v, others 120v. I just call it house current.
 
Originally Posted By: labman
An electrician or the power company may be able to reset the taps of the transaformer.


yes

It might have been set that way to compensate for voltage drop for a previous occupant who used a lot of power.
 
Originally Posted By: SecondMonkey
But when I tested my regular "110 volt" outlets, they read 138 volts! I know 110 isn't supposed to be an exact number, but 138 seems awful high!


The electric companies have slowly raised the voltage over the years to help stop the loss of electricity between the power station and your plug in outlets. The higher the voltage, the less loss they have.
Older appliances, such as tube audio amps, have a hard time with the increased voltages.
Typical household voltages now run from about 118 to 125, but can vary all over the place. If your measurement is indeed accurate at 138, it is too high.
Call your power company and have it measured and adjusted.
 
It will also burn out the ballasts in your fluorescent tube lighting. I have had this problem with one of my restaurants until the Power Co came out and admitted there was a problem. They paid $1200 to my Franchise Owner for all the electrical stuff he had replaced that looked like it had been slowly fried over the year.
wink.gif
The voltage was anywhere between 134 - 136 volts
 
Originally Posted By: Kruse
Originally Posted By: SecondMonkey
But when I tested my regular "110 volt" outlets, they read 138 volts! I know 110 isn't supposed to be an exact number, but 138 seems awful high!


The electric companies have slowly raised the voltage over the years to help stop the loss of electricity between the power station and your plug in outlets. The higher the voltage, the less loss they have.
Older appliances, such as tube audio amps, have a hard time with the increased voltages.
Typical household voltages now run from about 118 to 125, but can vary all over the place. If your measurement is indeed accurate at 138, it is too high.
Call your power company and have it measured and adjusted.


+1
Cut all breakers off to the building as to insure 0 current flow and measure the voltage at the main breaker. This voltage will be very close to the output of the transformer. report this number to the power company if it is above 125 VAC. As some of the reports stated above, sometimes higher voltage is better becuase it reduces the current draw to get the same power, but running devices that were designed to run a particular voltage, on higher voltages will reduce life or blow them up. 138V is to high, get it fixed. Make sure your meter is reading VAC RMS. I dont think this is a major issue with most meters but there is a differance between RMS and Peak to Peak. Just make sure your meter is measuring true RMS and not some funky reading.
 
Originally Posted By: jstutz
+1
Cut all breakers off to the building as to insure 0 current flow and measure the voltage at the main breaker. This voltage will be very close to the output of the transformer.

Is the building three phase? You will get some odd voltages with three phase if things aren't just right.
Or you may have a bad neutral connection somewhere. If there is a load on the circuit anywhere, a bad neutral connection will cause the system to "see" a 240 circuit running all your L1 and L2 (i.e. 120 volt to nuetral) circuits in series. The voltage will devide up across the various load, and you will have >120 volts on some, and Disconnecting everything should show true X-fmr secondary voltage at the panel. If in doubt, call a professional.
 
Originally Posted By: crinkles
why do different countries use different voltages? i always thought 250 was the norm.


A lot of countries use 110V to 120V with some at 100V and 127V. They are either 50Hz or 60Hz.

Most of the 110/120 countries are in North America or have close ties to the US. The US prolly has 120V because they were the first major country to be electrified. Other countries have 220/240 because they had more time to think about it. There was lot of paranoia about AC electricity in the US in the 19th century, let alone 240VAC. Then there is the mess with electrical plugs in different countries
http://www.kropla.com/electric2.htm

Much the same deal with TV standards, the US has NSTC because we were first, other countries have better systems because they cam along later.

I would be interested in
Shannow's opinion, but I think 240V 60Hz is the best combination of existing standards for household use.
 
I've recorded as high as 127VAC in my area before, and while notifying hydro to lower it, I've been proactive in switching most of my gears along the way to cope (more like keep up to) with the variances.

I now have all my fluorescent lighting on full electronic ballasts that can take it all the way up to 148VAC and still keeps on ticking.. (Timex commercials)

I have all my gears on UPSs with AVRs.

I have my audio gears on an automatic buck/boost regulator.

I have surge arrestors up da ying-yang.

Whenever I spec'ed an audio design for PNW area customers, I request my custom Japanese tranformer winder to make it 120V AC/60Hz instead of the old 117V AC.

2c's worth.

Q.
 
138 volts times 1/2 of the squareroot of three, (a common three phase voltage division)~.866 is 120 volts. Makes me suspicious you have a three phase system that is either miswired or a failed connection.
 
Actually, the more I think about it, someone might have just improperly center-tapped a 277 volt circuit. I really wouldn't get into a panel, especially a 480/277 volt panel, unless you know what you are doing.
 
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