3

Details: 240/120V split phase

Using my clamp on amp meter the readings on leg A was 3.2. on leg B 2.6 ( a .6 difference ). The neutral read 1.9 ( a 1.3 difference ).

Is the 1.3 Amps something to be alarmed about? If not, what would be considered reasonably alarming?

  • What are your expectations? Don't forget it's split phase. – Tyson Nov 9 '16 at 18:52
  • @Tyson I'd expect the neutral to carry the imbalanced load of .6 not 1.9 – Kris Nov 9 '16 at 19:40
  • What loads are present on this circuit, and is your clamp meter average or RMS responding? Also, do you have access to a power quality analyzer capable of recording multiple voltage and current channels, or an oscilloscope with CAT II 150V (min) inputs as well as a pair of current clamp probes? – ThreePhaseEel Nov 9 '16 at 23:26
  • @ThreePhaseEel, residential circuits i.e., general lighting loads, small computer, maybe a few smart switches. I believe RMS. I'm using a Fluke 376. No oscilloscopes. Just the clamp around the main service legs. – Kris Nov 10 '16 at 1:34
  • With Measurements made on loads that have nonlinear characteristics the totals don't always add up the way you would expect. Variable speed motor drives, dimmer circuits, modern flouresent ballast are all devices that can cause interesting voltages and diferent amp draws on each leg. – Ed Beal Nov 10 '16 at 2:53
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With Measurements made on loads that have nonlinear characteristics the totals don't always add up the way you would expect. Variable speed motor drives, dimmer circuits, modern flouresent ballast are all devices that can cause interesting voltages and diferent amp draws on each leg. I thought I would also add on a 20 amp electronic furnace I recently worked on when running at low speed had over 9 amp imbalance but at full speed the the imbalance was less than 1 amp. For this reason the NEC considers the neutral to be a current carying conductor with nonlinear loads.

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