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I have 252v coming into my building (126 per leg) and a piece of equipment which uses a percentage timer that has a small motor on it which is rated for 120v. Will 126v fry the motor?

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  • \$\begingroup\$ That's an 8% difference. I think it should be okay. It will run a bit hotter than normal though. But it's a hunk of steel and copper. It'll be more tolerant of variances than a semiconductor. \$\endgroup\$ – DKNguyen May 2 at 22:17
  • \$\begingroup\$ So, is this US/Canada split-phase? Just curious. In general and in the US, the customer service voltage standard allows from \$114\:\text{V}\$ to \$126\:\text{V}\$ per phase on a standard split-phase system. Your voltage appears to be on the high end (assuming you measured it correctly using an RMS meter which is more expensive to buy.) But motors are supposed to tolerate the range. So you are probably fine. \$\endgroup\$ – jonk May 2 at 22:21
  • \$\begingroup\$ If curious, look up "American National Standard for Electric Power Systems and Equipment – Voltage Ratings (60 Hertz)" (the 1st edition came out in 1954.) \$\endgroup\$ – jonk May 2 at 22:44
  • \$\begingroup\$ In Can/USA , you can expect tolerances 120 +/- 10% which motors are usually rated for. but typically < 5% supply tolerances are offered \$\endgroup\$ – Sunnyskyguy EE75 May 2 at 23:20
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    \$\begingroup\$ Wow, one of those old Eagle timers? They were built like a tank and should be fine. \$\endgroup\$ – Spehro Pefhany May 2 at 23:21
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The nameplate is your "goto" for this information. It must tell you the operating voltage range.

e.g. enter image description here

This one is "universal".

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    \$\begingroup\$ It says 120v. However, I have 126v per leg coming in to my building. My question is can it handle that. \$\endgroup\$ – Michelle Bankey May 3 at 0:40
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    \$\begingroup\$ If it only says 120V then assume it can tolerate 10%, however if you switch large motors with that, it may reduce contact life \$\endgroup\$ – Sunnyskyguy EE75 May 3 at 0:41
  • \$\begingroup\$ Nice to know Sunnyskyguy. It controls 2 contactors that turn a set of heating elements on & off every 15 to 30 seconds. \$\endgroup\$ – Michelle Bankey May 3 at 2:08

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