Freezer with 57 volts on the frame?

[tortuga]

I had an after hours service call yesterday evening.
After two plug in space heaters were set to 'hi' home owner tripped a breaker.
Upon resetting breaker they were still without some power.

I get there and find two GFCI's tripped that are on completely unrelated circuits.
Bathroom one resets fine.
Kitchen one wont reset.
Its a 1969 house so some garage recepts are down stream of the kitchen GFCI.
I unplug the freezer and the GFCI resets.
I had an ideal 'sure test' with me.
All voltage readings normal, outlets are all grounded and have been replaced in the last 2 years.

I have a 3 prong to two prong adapter in my test bag, plug in freezer with adapter and GFCI holds.
I take the freezer plug off the GFCI test again this time measuring voltage from the frame ground to the ground pin on the outlet.
I get 57 volts.
I am still into this service call under 10 minutes.
This kitchen / garage circuit had nothing to do with the space heaters that tripped the breaker.
The name plate of the freezer says 5 amps, my ammeter is measuring about 8.

Why would a overload on a totally different circuit cause this?

 

[480sparky]

MWBC with an open neutral.

 

[Dennis Alwon]

Check for a multiwire branch circuit. The 5 amps vs 8 amps may be the ampmeter itself or something is making the freezer work harder.

With gfci's it is no telling why different circuits would trip

 

[g-and-h_electric]

Ignoring the tripped GFCI in the bathroom, and the overloaded circuit for a minute (they are apparently unrelated to the kitchen). My opinion is that there MAY be either a bad compressor (hence the higher current reading) or a bad defrost heater in the freezer which is causing the leakage current. How old is the freezer, it may be reaching the end of it's useful life?

Just my thoughts based upon my albeit limited knowledge of refrigeration equipment.


Howard

 

[480sparky]

A defective or dying unit would be my next choice. Megger it at 120v or less.

 

[tortuga]

Yeah I had opened the panel and looked for MWBC's and there were none.
Grounding and service all seemed fine.
the freezer definitely seemed like it was not new.
I recommended a new freezer.
But what bewildered me is why did it go bad at the exact same time as a totally different circuit tripped a breaker?

 

[Dennis Alwon]

Yeah I had opened the panel and looked for MWBC's and there were none.
Grounding and service all seemed fine.
the freezer definitely seemed like it was not new.
I recommended a new freezer.
But what bewildered me is why did it go bad at the exact same time as a totally different circuit tripped a breaker?

It may be some power company issues that are coming and going

 

[Fred B]

I've seen a few go bad after a surge event from utility, it too tripped some odd circuits unrelated to the fridge. It seemed to fry the circuit board, installed SPD and that seemed to stop the issue, one customer was replacing or repairing the fridge several times in just a couple of years, hasn't had an issue since putting on a whole house SPD. Odd thing was it fried the fridge but not the tv.

 

[ptonsparky]

Could be you just got ‘lucky’ to be there at the right time.

 

[ramsy]

I've seen a few go bad after a surge event from utility..

Yes, utility xfmrs replaced by attrition in my area have failed in spectacular fashion. Lots of smoke and crackling brings out the spectators

One failure selectively destroyed all low voltage Class-2 xfmrs in several homes. All doorbells, many appliance clocks, and T-Stats

Don't know if surge protection could have made a difference.

 

[hbiss]

Could be you just got ‘lucky’ to be there at the right time.

Bingo! Bathroom had nothing to do with the freezer. It was tripped for two days but of course the customer won't tell you that.

-Hal

 

[Eddie702]

Bad freezer would be my guess. Something in the freezer leaking to ground. Probably the compressor

 

[flashlight]

Could be you just got ‘lucky’ to be there at the right time.

That's my vote. I never win the lottery, but I seem to get lucky that way sometimes.

 

[tortuga]

Thanks all for the replies.
If the freezer had not been running fine on a GFCI for two years, I might have been more inclined to look for a way to take it off a GFCI.
I dont have a meter that can measure mili-amps,

Which leads me to a theory question:
Is it possible to solve for miliamps of leakage from the two voltage readings? Vsource and Voutput
Like a voltage divider circuit?

Cheers all

 

[ptonsparky]

Put a resistor in series with the EG. Connect to a non GFCId circuit and measure the VD. OHMS law. I haven’t had to do it since school. Bought the meters instead.

Wear your gloves.

 

[drcampbell]

Degraded insulation in the motor windings could explain both leakage current (if there's a short to ground) and excessive current. (if there's a turn-to-turn short) Most small hermetic refrigeration compressors pass refrigerant vapor directly over the motor windings, which are vulnerable to contamination. (moisture in the refrigerant can form acids, and overheated oil leads to something else bad ... I forget what, maybe coke buildup)

Which, I acknowledge, it probably overthinking things. Measure the ground fault and red-tag the freezer if need be. Be careful, that 57 volts might have a very low impedance behind it if it's the result of a motor-winding short.

 

[tortuga]

Put a resistor in series with the EG. Connect to a non GFCId circuit and measure the VD. OHMS law. I haven’t had to do it since school. Bought the meters instead.

Wear your gloves.

Gotchya thanks

I was thinking somthing similar to the formula for a voltage divider, but with only one resistance:

Vo = Vs X R / R
therefore
R = Vo / Vs-Vo

but that gave me 132 amps on the the ECG surely that would have tripped the 20A breaker.

 

[Dim&Dimmer]

Had a door gasket heater go bad and short out to the frame. Didn't trip the circuit(no gfci) but I could measure voltage and the bartender could feel it.

 

[kwired]

A defective or dying unit would be my next choice. Megger it at 120v or less.

Yep. ground fault but with high impedance so it doesn't get into trip range of the overcurrent device. The fact he eliminated the EGC will allow it to not trip the GFCI, might not run for too long before it fails further.