US electrical q:my 240v reads only 190v (lemmy.world)

submitted 1 month ago by Brkdncr@lemmy.world to c/asklemmy@lemmy.world

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Was fixing a bad wiring job between a sub panel and a 240v 2 phase water pump and noticed that my multimedia was only testing it as 190v. Checked back at the breaker and saw the same. Checked between L1 and L2 on a different breaker and saw the same.

My 240v equipment (dryer, oven, water heater, 2 HVAC units) all work fine.

Should I be concerned?

How big of a deal is this? Like call an electrician asap or wait until I have some other electrical work lined up?

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[-] Brkdncr@lemmy.world 3 points 1 month ago

Typical residential is delivered as 2 phases that are moving back and forth 180 degrees out of sync. If you wires just one of those phases you get 120v. Wire them both and you get 240v.

There’s 3-phase but that’s mostly found in commercial buildings, and you typically get either 208v or 120v depending on if you wire one or two of the 3 wires.

[-] Canopyflyer@lemmy.world 1 points 1 month ago

Power delivered to homes in the US is Split Phase. Meaning the distribution transformer was wired to a single distribution phase and it is center tapped. So you would get 120vac A to center, or B to center, but 240ac from A to B.

If it was 2 phase they would be 120 degrees out of sync and would deliver 208vac.

this post was submitted on 16 Feb 2026

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