Replies

1. 
   pye | Mar 13, 2005 08:53am | #1

   Call your local utility and explain the problem, they should send out a serviceman with a true rms meter to confirm your "overvoltage". They can change the taps on the transformer. 125/250 isn't far enough out of range to cause failures, go down to any electrical supplier and you'll find 130volt rated light bulbs.

2. 
   4Lorn1 | Mar 13, 2005 11:07am | #2

   This is not an uncommon reading. A true RMS meter would get a bit more accurate reading but, contrary to common belief among many, it is seldom excessive voltage that causes problems.

   Some of this has to do with what we call 'nominal voltage ratings'. Motors are commonly rated at 115v or even 110v. Most people speak of 120v. Essentially all these are referencing the same thing. A motor with 110v on its nameplate will run fine on what we call 120v.

   In fact motors are in far more danger of low voltage than high. As long as the high end doesn't go too far. Running a 120v universal motor, unless it is designed for it, on 240 makes it run quite well. Just not for very long.

   Trick is that motors are essentially constant power devices. The power coming in both voltage and amperage. What a motor cant get in voltage it will try to make up with amperage. When amperage climbs the thin wires that make up the motors windings begin to heat up. When they reach the point that the insulation gives up the windings short out and the magic smoke comes out. Which is why overworked motors, too heavy a load or too low voltage, typically can be smelled. Slightly higher voltage saves motors. Chronically low voltage destroys them in short order.

   Most utilities have standards as to what they consider too high or low. Most utilities will send out a lineman to check the readings at your meter. Typically anything 118v to 126v, with a preference for the higher end, is considered normal.

1. 
   JohnSprung | Mar 14, 2005 09:41pm | #11

   > Most utilities have standards as to what they consider too high or low.

   LADWP told me that their standard is the nominal voltage plus or minus 5%, as measured at the service entrance.  That would be 114 - 126 for a nominal 120 volt service.

    

   -- J.S.

    

3. 
   savvy | Mar 13, 2005 12:46pm | #3

   Your 120v nominal voltage may not be exactly 120 due to voltage drop.from about 125 to 108v is ok. It sounds like there is not much drop & that you are close to the transformer.If you are getting power to the machine, I respectfully disagree with the rep you spoke to. I would look at the switch & then the machine itself.I would not look to the power co .
   Todd

4. 
   savvy | Mar 13, 2005 12:49pm | #4

   I forgot to add, also, look at the motor id plate on that machine & make sure its not 3 phase
   Todd

1. 
   4Lorn1 | Mar 13, 2005 02:49pm | #5

   Very good point.Runnning a three-phase motor on single phase 240v, if it runs at all, will destroy the motor.

2. 
   BillHartmann | Mar 13, 2005 02:50pm | #6

   Here are the standards;http://users.metro2000.net/~purwinc/seec2_2.htm
   "
   ANSI C84.1 "Electric Power Systems and Equipment - Voltage Ratings (60 Hz) sets the preferred nominal voltage at 120V and allows a range of 114 - 126V (240V nominal, range 228 - 252V). Equivalent Canadian spec is CAN3-C235."EXCEPT IN CALIFORNIA!"However, the California Public Utilities Commission has specified that the service voltage shall be kept in the range 114-120V, with some exceptions. This was done because some studies showed a reduction in energy consumption at the lower voltages."Here is a slightly more detail spec from one utility compnay.http://www.pge.com/docs/pdfs/biz/power_quality/power_quality_notes/understanding.pdf

5. 
   Sphere | Mar 13, 2005 08:22pm | #7

   I have had an accumulation of dust in the mag switch cause that, have you opened it and blown it out?

    

   Spheramid Enterprises Architectural Woodworks

   "Sell your cleverness, Purchase Bewilderment"...Rumi

6. 
   DaveRicheson | Mar 13, 2005 11:52pm | #8

   So what is voltage of your jointer?

   What did the rep talk you through?

   I have a Delta JD-8  at 230v and it has a magnetic switch (Furnas). I also have a Delta Unisaw with a magnetic starter. Two different animals, so it would help to know what you have.

   A magnetic switch is easily checked and replaced. As 4Lorn1 pointed out, plug a 120v corded device into a 230v source and that switch will burn out first, and open so you don't cook the motor.

   If it is a magnetic starter, it takes up considerably more room. The switch may look the same, but will be fed from a box containing  a transformer, relay and a contactor. the cover should have a schematic inside, showing the wiring. Somewhere in that circuitry is ussually a fuse. It is sacrificial to save both the motor and the contactor. Locked rotor amperage will blow the fuse, if you maybe forgot to take the shipping braces off of something, or something was wedged in the cutter head on start up.

   I am with the others. Your voltages are within nominal ranges. The rep is not trouble shooting for you, he sidestepping warrenty issues, if all else is set up correctly.

   Tell us what you have, and what (how) you tested.

    

   Dave

1. 
   lostarrow | Mar 14, 2005 02:19am | #9

   I've been using the joiner for about 2 weeks with no problem, it had a couple of shudders when it started a few times, but nothing major.  The switch is magnetic, and the service rep is sending a new one.  I tested the power with a Fluke multimeter.  The rep had me try the switch in the normal wire configuration and then bypass the switch, and the joiner works.  Ergo the switch is bad.  I was just asking if 125/250 was high for household volage, we already know the switch is bad, just wondering why it went bad. Thanks for the help, I appreciate it.Be not afraid of going slowly.  Be afraid only of standing still.   chinese proverb

1. 
   DaveRicheson | Mar 14, 2005 02:17pm | #10

   Sounds like he stood behind the warrenty. Good for you.

    

   Dave

7. 
   DanH | Mar 14, 2005 10:28pm | #12

   Like others have said, the voltage won't hurt your motorized equipment. If the voltage measurement is confirmed, though, and the utility folks don't lower it, you should consider using 125 or 130V incandescent light bulbs in place of any 120V bulbs you have. (Fluorescents should be OK,)