Multiplier issue

[Max]

Hi All,

I just put a Emporia clam on one leg of hot tub breaker, but readings seem wrong, it shows 20AMP while it should be really only 10Amp, as pumps are rated at max 5

 

should multiplier be set to 2 or should I put clam on each leg

[djwakelee]

Correct.  For monitoring 240V circuits, you can either…

1) Use one clamp and specify a multiplier of 2.

(or)

2) Use two clamps (one for each hot leg), and manually add the two readings for the total power.

Also – there is a bug presently with Amps regarding incorrect math and false readings.  Only power works correctly as above.

[djwakelee]

Also, hot tubs typically require clamps for both legs since most hot tubs are unbalanced loads.  Heater and pumps typically 240V, but the electronics often run on just one of the 120V phases.

[msturtz]

@djwakelee that’s not universally true, in fact its actually fairly uncommon.  Most often, a tub will only get 220V, by way of two legs 180 out of phase, and a ground, but NOT a neutral.  Usually the equipment pack will have a small transformer/power supply on or near the circuit board to power the electronics (control panel, lights, audio, etc), but it’s still balanced since that runs on 220 without a neutral.  All the equipment, including pumps, and of course the heater, will always use 220V regardless if there’s a neutral or not.  The one exception is (or was since they aren’t common anymore) was blowers, which could go either way.  Ozone units can be ordered either way, but 220V is very common.

@Max if your hot tub has a neutral wire (white wire, or white tape hopefully, going to the neutral bus bar in the panel, or look in the hot tub panel where the conduit comes in — are there 3 wires or 4?), you technically should use one sensor on each leg, however even if it is there, the huge majority of the tub’s power usage will be balanced, so one sensor on one of the two hot wires, with a multiplier of 2 in the app, will most likely be very close even if a very small part of the load is unbalanced.

• This reply was modified 3 years, 5 months ago by msturtz. Reason: typo / grammatical correction

[djwakelee]

@msturtz The guiding rule for determining balanced or unbalanced 240V (hence one clamp or two) is if your device has a neutral connection.  If it does have a neutral (white wire), you should use two clamps.  Same as a subpanel.  In my case, my hot tub does have a neutral connection (and ground).  Main pumps and heater 240V, circulating pump and electronics on 120V – so substantial imbalance.  No transformer or equipment pack like you mention, 2 hots, neutral, ground directly wired to the controller.  Can’t say which is more common, but my unit is a MasterSpa, Down East model circa 2006.  National Electrical code requires 50A GFCI on hot tub circuit, with neutral wired through the GFCI as is typical.

[Max]

Hi friends,

 

I do have 3 wire + ground …

So question is, is there way sin Emporia to combine two clamps or do I always have to switch back and Fort and manually add numbers, which is not a big deal but just wondering

 

thank you

[djwakelee]

For now, you need to manually add the two phases.  Combining them in the software is one of the most requested features, and is supposedly coming with the next major app update.

[Author]

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