Cooler lights getting only 80V

[jeremysterling]

Here's the scenario:

Trouble call for 4 lights not working in "frozen pizza " cooler.

Cooler in question is Zero Zone 5-door frozen food retail show cooler. There are three 2-lamp F40 T8 ballasts.

For troubleshooting, all the heat trace in the five doors are unplugged.


When the ballast leads are loose from the line, the line reads 120V (116V).

When any of the three ballast loads are tied to the line, the line drops to 80V.

By chance, the cooler cycled into defrost and the circulating fan quit running. Coincidentally, all six T8 tubes come on full bright. When defrost cycle ends, fan comes on and lights go dim again. Two additional cooler cases share this circuit but are working OK. Light circuit is pulling around 3 amps while the middle cases ballast are at 80V.

Why is this happening?

How is this fan circuit affecting the light circuit? I assumed the heat trace, lights and fan were all on the same circuit, but I don't know for sure.

 

[mxslick]

Is the cooler fed by 240/120v or 208/120 single or three phase?

In any event sounds like a classic case of an open neutral.

Or, if single phase, you have a bad connection in the hot line that sags under load. If the compressor is working normally then the problem is internal to the unit.

 

[Cow]

How are you checking voltage?

I'd check both L-N and L-Gr. You need to know if it's a line or neutral problem affecting voltage.

I've had a wire fault to ground before that sagged the voltage quite a bit, but it would not trip the breaker until you put a good load on it.

I would also make absolutely sure the fan isn't sharing the same circuit as the lights.

 

[kwired]

Is the cooler fed by 240/120v or 208/120 single or three phase?

In any event sounds like a classic case of an open neutral.

Or, if single phase, you have a bad connection in the hot line that sags under load. If the compressor is working normally then the problem is internal to the unit.

I agree most likely an open neutral someplace.

But the compressor probably has nothing to do with it because it is most likely located remote from the freezer case. And most likely the compressor wiring is not even related or even interconnected to wiring of the case.

These freezer thermostat usually turns on a valve in the refrigerant line an the compressor starts and stops on refrigerant pressure. The only connection between the two units is refrigerant lines no wiring.

 

[mxslick]

I agree most likely an open neutral someplace.

But the compressor probably has nothing to do with it because it is most likely located remote from the freezer case. And most likely the compressor wiring is not even related or even interconnected to wiring of the case.

These freezer thermostat usually turns on a valve in the refrigerant line an the compressor starts and stops on refrigerant pressure. The only connection between the two units is refrigerant lines no wiring.

Not necessarily, if this is a cord and plug connected unit the compressor gets its power from the same source as the lights, etc.

That's why I said that if the compressor is working normally the fault is internal to the unit as opposed to the power source.

But you're right if it's a larger unit (like a walk-in for example) where the refrigeration system is totally separate in the electrical sense.

So the OP needs to fill us in on how this unit is powered and at what voltage/phase setup. :grin:

 

[Cavie]

I'll NEVER understand the question. "When I disconect the load I have 120 volts. When I connect the load I have xxx (less that 120)volts. What is the problem???. My answer to that question is " Put the tools down, back away and call an electrician!" Basic electricity 101.

 

[kwired]

Here's the scenario:

Trouble call for 4 lights not working in "frozen pizza " cooler.

Cooler in question is Zero Zone 5-door frozen food retail show cooler. There are three 2-lamp F40 T8 ballasts.

For troubleshooting, all the heat trace in the five doors are unplugged.


When the ballast leads are loose from the line, the line reads 120V (116V).

When any of the three ballast loads are tied to the line, the line drops to 80V.

By chance, the cooler cycled into defrost and the circulating fan quit running. Coincidentally, all six T8 tubes come on full bright. When defrost cycle ends, fan comes on and lights go dim again. Two additional cooler cases share this circuit but are working OK. Light circuit is pulling around 3 amps while the middle cases ballast are at 80V.

Why is this happening?

How is this fan circuit affecting the light circuit? I assumed the heat trace, lights and fan were all on the same circuit, but I don't know for sure.

Not necessarily, if this is a cord and plug connected unit the compressor gets its power from the same source as the lights, etc.

That's why I said that if the compressor is working normally the fault is internal to the unit as opposed to the power source.

But you're right if it's a larger unit (like a walk-in for example) where the refrigeration system is totally separate in the electrical sense.

So the OP needs to fill us in on how this unit is powered and at what voltage/phase setup. :grin:

All units that fit the description the OP gave that I have ever seen had remote compressor. I suppose there could be some that are self contained. All the self contained ones I have ever seen are not larger than two doors.

 

[Cow]

I'll NEVER understand the question. "When I disconect the load I have 120 volts. When I connect the load I have xxx (less that 120)volts. What is the problem???. My answer to that question is " Put the tools down, back away and call an electrician!" Basic electricity 101.

Just like I'll never understand guys like yourself, who post in a thread only to criticize instead of offering anything useful to the posters question.:roll: You know, that's basic manners 101.

And he is an electrician.

 

[Mgraw]

Zero-Zone makes 3 door self-contained. A five door probably has a remote condenser. The light T-stat could be going bad. They are usually just a snap-disk type. Sometimes the contacts get pitted.

 

[hardworkingstiff]

I'll NEVER understand the question. "When I disconect the load I have 120 volts. When I connect the load I have xxx (less that 120)volts. What is the problem???. My answer to that question is " Put the tools down, back away and call an electrician!" Basic electricity 101.

:grin: :grin:

Just like I'll never understand guys like yourself, who post in a thread only to criticize instead of offering anything useful to the posters question.:roll: You know, that's basic manners 101.

And he is an electrician.

Rut roh,

 

[jeremysterling]

Is the cooler fed by 240/120v or 208/120 single or three phase?

In any event sounds like a classic case of an open neutral.

Or, if single phase, you have a bad connection in the hot line that sags under load. If the compressor is working normally then the problem is internal to the unit.

I'll guess 208/120. I never found the breaker, I'm guessing it's in the compressor house. (I've not been in this type of store's compressor house before).

I found a big 24X24 j-box about 30 feet from the cooler with a lot of connections 10's and 8's. Found the red 10 supplying the lights. It comes in with a four wire boat. The same red circuit supplies lights to coolers on either side of the one in question. Those cooler lights work fine.


I think three coolers lights are on the red and three coolers fans are on a different circuit on the same neutral.

I think you are right about high resistance neutral connection for the MWBC that supplies lights and fans in my problem cooler.

But, it could be a high resistance short to ground or a the bad hot connection you alluded to. My volt measurements were the same from hot to N and/or G. N and G read continuous when ohmed.

It got late in the day, far from home, so I decided against pulling the kick plate to check the internal wiring beneath. I had already wasted my time checking the wiring chases between and above all five doors, all the while obliging customers selecting frozen pizzas between dangling ballasts. Some of you know this drill.

So right then, late in the day, the cooler fans shut off and a hint of the problem shows itself. Arghhh!

Nameplate data:

Lights 4.5A@120V
Anti-sweat 12.6A@120V
Fans 3.0@120V

Defrost 15.9A@220V

If I broke the red wire joint, three cooler's lights turned off, but when I amp-clamped it under load, it was only 3.5 A. So, I'm not sure if the name plate was including all three coolers.

I tried to call Zero Zone but the number on the nameplate was no good, but then a shopper made up for that by loudly and falsely accusing me of taking a picture of her backside with the cell phone I was attempting to get tech support with. Arghh!

I'll NEVER understand the question. "When I disconect the load I have 120 volts. When I connect the load I have xxx (less that 120)volts. What is the problem???. My answer to that question is " Put the tools down, back away and call an electrician!" Basic electricity 101.

Right. Just a regular parallel ckt. Or is it a series parallel circuit? Unfortunately, I will never know. I ran out of time and referred this mess to the cooler tech.

 

[mxslick]

Zero-Zone makes 3 door self-contained. A five door probably has a remote condenser. The light T-stat could be going bad. They are usually just a snap-disk type. Sometimes the contacts get pitted.

Curious, why would the lights have a t-stat? Or are you talking about a thermal overload in the ballast?

I'll guess 208/120. I never found the breaker, I'm guessing it's in the compressor house. (I've not been in this type of store's compressor house before).

I found a big 24X24 j-box about 30 feet from the cooler with a lot of connections 10's and 8's. Found the red 10 supplying the lights. It comes in with a four wire boat. The same red circuit supplies lights to coolers on either side of the one in question. Those cooler lights work fine.


I think three coolers lights are on the red and three coolers fans are on a different circuit on the same neutral.

I think you are right about high resistance neutral connection for the MWBC that supplies lights and fans in my problem cooler.

But, it could be a high resistance short to ground or a the bad hot connection you alluded to. My volt measurements were the same from hot to N and/or G. N and G read continuous when ohmed.

It got late in the day, far from home, so I decided against pulling the kick plate to check the internal wiring beneath. I had already wasted my time checking the wiring chases between and above all five doors, all the while obliging customers selecting frozen pizzas between dangling ballasts. Some of you know this drill.

So right then, late in the day, the cooler fans shut off and a hint of the problem shows itself. Arghhh!

Nameplate data:

Lights 4.5A@120V
Anti-sweat 12.6A@120V
Fans 3.0@120V

Defrost 15.9A@220V

If I broke the red wire joint, three cooler's lights turned off, but when I amp-clamped it under load, it was only 3.5 A. So, I'm not sure if the name plate was including all three coolers.

I tried to call Zero Zone but the number on the nameplate was no good, but then a shopper made up for that by loudly and falsely accusing me of taking a picture of her backside with the cell phone I was attempting to get tech support with. Arghh!



Right. Just a regular parallel ckt. Or is it a series parallel circuit? Unfortunately, I will never know. I ran out of time and referred this mess to the cooler tech.

Thanks for the info... so as kwired stated the compressor would indeed have nothing to do with this issue.

Since the other units served off that red #10 are working properly, sounds like the unit in question has an internal problem.

 

[peter d]

Was this particular case swapped out recently? Off the top of my head I would guess someone didn't keep track of the connections from the branch circuits to the case itself. Something sounds like it's crossed up internally.

Bob (Iwire) has a good story about an EC who wired up refrigerated cases and didn't keep track of the circuitry and where it was fed.

In the supermarkets I've worked on, the fan circuits originate in one panel, the defrost in a defrost control unit, the lighting in a contacted panel, and the refrigeration control in the compressor control on the rack itself.

 

[Mgraw]

Curious, why would the lights have a t-stat? Or are you talking about a thermal overload in the ballast?

Coolers usually don't have T-stats for the lights. Freezers usually do. They prevent the lights from coming on before the freezer reaches a certain temperature. Usually about 5F-0F. Some manufacturers use them as an alarm. If the temperature goes above a preset limit the lights go off. Some manufactures, Zero-Zone included, mount the Klixons on the evaporator coil which means everytime the freezer goes in defrost the lights will go off. They are usually installed on lights, fans and defrost heaters.

 

[jeremysterling]

Since the other units served off that red #10 are working properly, sounds like the unit in question has an internal problem.

Yeah, that's what I came up with.

Was this particular case swapped out recently

Close. I think it was remodeled several years ago and I suspect what you suggest:

Off the top of my head I would guess someone didn't keep track of the connections from the branch circuits to the case itself. Something sounds like it's crossed up internally.

Bob (Iwire) has a good story about an EC who wired up refrigerated cases and didn't keep track of the circuitry and where it was fed.

In the supermarkets I've worked on, the fan circuits originate in one panel, the defrost in a defrost control unit, the lighting in a contacted panel, and the refrigeration control in the compressor control on the rack itself.

Coolers usually don't have T-stats for the lights. Freezers usually do. They prevent the lights from coming on before the freezer reaches a certain temperature. Usually about 5F-0F. Some manufacturers use them as an alarm. If the temperature goes above a preset limit the lights go off. Some manufactures, Zero-Zone included, mount the Klixons on the evaporator coil which means everytime the freezer goes in defrost the lights will go off. They are usually installed on lights, fans and defrost heaters.

Thank you to everybody who responded to this thread. I learned a lot from all of you. Keep up the good work!