MemberMay 16, 2020 at 5:31 pm
We have had an issue with our Norlake walk-in cooler/freezer tripping not only its own breaker but multiple others at the same time. This has stumped multiple electricians and HVAC techs so I figured I would see if any of you have run into a similar issue or have any advice. I want to preface this with the fact that this is in a newly remodeled store, about 3 years ago we started completely gutting the building down to the studs and redid everything. The panel was added during the remodel and all the equipment was brand new and only in use for about 2.5 years now.
For the last 2 months we have had this issue, on and off with almost no consistency of what leads up to it, with our Norlake unit tripping its own breaker and at the same time it trips, between 1 and 7 GFCI breakers on the opposite side of the panel trip with it. When this issue first started it only tipped the 1-3 GFCI breakers directly across from it on the panel but now it almost always all 7 GFCI breakers on the opposite side. Up until about a week and a half or two weeks ago it was happening about every other day. A local HVAC company replaced a contactor that had a middle leg that was sticking and both the fan motors which were starting to bind up. Everything was good so we assumed it was a surge coming down from the unit when the motor overheated due to the sticking middle leg.
Now it is starting again, on the 14th overnight the Norlake tripped but only itself nothing else. We call the HVAC company and they sent someone else down on the 15th to get a new set of eyes on it and see if they can solve it. He took amp draws, checked every connection on the unit, and even checked the capacitors to see if one of them was starting to go bad. He found one of the time clocks is starting to stick, which is a whole different issue on this 2.5 year old unit we have replaced it 3 times after this one, but nothing else. Now today, the 16th, the Norlake unit trips again during the afternoon and takes 5 of the GFCI breakers with it.
The equipment that is on the GFCI breakers are on the single phase side of the panel and 4 are 20 amp breakers and 3 are 30 amp.
The Norlake is a 3 ph circuit and on a 35 amp 3 pole Eaton BR335 breaker, the combined amp draw of both compressors turning on at once is 16 amps so well below our 35 amp breaker. The HVAC tech noticed the unit had some 40 amp fuses in the control box and suggested upsizing the breaker from 35 to 40 to see if we can get one of the fuses to blow to narrow down what is causing the breaker to trip. If we do upsize the breaker we will have to check the wire size that the electricians installed as it may require upsizing the wire, which during the current global situation we would prefer to not have to do as cash is king right now.
The electrician who installed the panel and did most of the electrical work during our remodel came and looked at the panel. He checked the voltages, amp draws, and condition of the wires inside, as far as he could tell everything is fine. He did say he was going to look into if the GFCI breakers not having a neutral wire could possibly cause them to trip if the Norlake unit sent a surge down to the panel but they are on 240V set up and do not need a neutral wire.
If you have made it through all that and understand it I would love your input if you have any sort of experience or idea as to what is causing our issue. At this point we are really at a loss of what to do or what tradesman should be the one to fix or find the issue as both have never seen this happen.
MemberMay 17, 2020 at 11:10 am
My first thought is a short.
GFCI circuits, breakers, outlets, etc. all work by comparing neutral to ground and if the ground gets amperage exceeding it’s limits, it kills it.
GFCI breakers are normally wired to a neutral, otherwise they don’t work. I just installed a 220V circuit a couple of weeks ago and wired it to a 2 pole 20 A GFCI breaker but there was a neutral wire with it that wired into the panels neutral bar. If I remember correctly.
Only thing I can imagine is your unit is somehow grounding or shorting in some way, could be the same wall or close to those outlet breakers tripping and it causes those GFCI breakers to register juice on the ground (due to something else) and it trips as it’s supposed to.
That’s my first thought, GFCI outlets normally trip due to shorts before the breaker trips.
Check this article out.
MemberMay 17, 2020 at 11:21 am
Take a look at this, page 3 shows how they wired a 3 phase circuit with a neutral, that’s how it should be.
GFCI doesn’t work without a neutral, it needs a way to compare. Most 3 phase systems have a ground fault interrupter that will do 30MA – 100 MA before it trips which is WAY too much to protect people, a normal GFCI outlet trips at 5-6 MA.
MemberMay 17, 2020 at 2:04 pm
Thank you for taking the time to read and respond. I talked with a couple of master electricians for about an hour yesterday and they said this is going to be a beast to figure out. That being said I appreciate any ideas until we figure this situation out.
The outlets are not GFCI just the breakers and they are on multiple different walls in the building. The Norlake cooler unit is a direct wire to the breaker which is not a GFCI breaker and on the opposite side of the panel.
Last night it tripped again, first time it has tripped twice in a day, so we are going to start with replacing the 3 pole breaker that the Norlake is on and see if it is just weak for some reason. I don’t expect this to be the reason for the GFCI breakers tripping but it is by far the cheapest and easiest possibility that we can start with. At the same time we are going to contact the city and see if there is a damaged wire between the transformer and panel.
MemberMay 17, 2020 at 2:07 pm
No problem, that’s why we’re here.
I’ve had a breaker trip randomly, kind of like what you are saying due to a bad compressor, it megged fine and everything SEEMED fine, replaced the breaker, outlet, start components, etc. still did it intermittently, replaced the compressor and the problem went away.
Wouldn’t explain why your other breakers trip but might be the problem on the cooler/freezer itself.
MemberMay 18, 2020 at 6:16 am
Ok, if your cooler breaker is tripping with a direct short the surge will trip other breakers. The sudden hard short to the ground circuit feeds back to the panel. Check the panel ground connections to be tight and the neutrals and grounds to be separate. A hard short can also induce current on near by wires. With walk in units it can well be the defrost heating circuit. It will not show up except during the defrost cycle. And then if related to expansion only at a certain point.
I have also run into a problem like this in a building remodel. The wires in the wall did not have guard plates and a sheet-rock screw hit a wire. But it would only short when the wall was hit or a door was slammed.
You never said what compressors you have. Make and HP. Some of the hermetic ones have motor hanging on springs with the power to the motor through a tape ribbon. In bigger ones the motor jumps a lot on starts. The ribbon tape can abrade if it touches something and then can short, usually during starting torque. And often only momentary. If you have a semi-hermetic, Check the tightness of the terminal post under the connection board.
Freezer compressors are low temp. If the box is above freezing at the start of cycle, they run in overload. To prevent this they use either a suction pressure regulator (crankcase regulator) or a pressure limiting expansion valve. Improper adjustment of either one will cause overload and trip, but may be erratic and delayed.
Make sure you breakers are HVAC rated. Also with multiple trip’s they get weak over time. Also the cooler and the freezer circuits should be separate feeds. If they are combined they have to have individual protection at the unit. Be aware that starting current is 17 times full run current. So if your building experiences power outages, both units would want to start at the same time. So combined, evaporator fans, condenser fans, and compressors may well exceed the single 45 amp breaker. You can install delays start timers to prevent this.
Good luck with this. I’ve chased down a few of these in the past. It takes time and monitoring. You may want to explore renting a power monitor to actually determine what is happening. Or borrow one from your power company meter and test department. GE used to rent them.
MemberMay 20, 2020 at 10:36 am
AHHHH, fixbear…. I think you got it. I was reading through all of this and the “randomness” was putting me off, then I realized he was talking about a freezer and the defrost kicking in throughout the day or at set points could be the “randomness” that has been coming into play.
One thing I would check is the wires/wiring connections on the heating coils of your defrost unit, perhaps some of the insulation came off and the build up of ice and melting of it is coming into contact with an exposed wire/connection creating this whole issue.
MemberMay 20, 2020 at 3:14 pm
I actually had a outside Leer ice bin with a similar problem. What I eventually found was a pin hole in the insulation of the defrost termination Klixon wire that only shorted when it got water conduction to the chassis. I believe it may have been made by a lightening strike, but could never prove it. There was no burn marks on the evaporator or cover. Yet a slight charring at the hole. And it had gotten down to ohm testing each wire and element in the defrost system before I found it. More hours than I want to admit to.
MemberMay 20, 2020 at 3:34 pm
Marketingtomaitenace may benefit a lot from a IR camera. Large production facilities have their electrical systems scanned annually for insurance discounts. One of my cousins got into the field back when cameras cost about $40,000. About 20 years ago. He went all over North America scanning panels and switch gear till the equipment got cheap. A cannon video camera, a laptop, and the IR camera. The highest concern for insurance claims with the big corporations is electrical fires. By imaging their systems they found a lot of problems before they became a issue. You can actually see a high resistance in a single pole of a contactor. A hot breaker pole. High resistance in a junction box.
Today you can buy a Cat Android S60 phone that does it all plus lazer measuring for $700
MemberMay 25, 2020 at 7:08 pm
MemberMay 26, 2020 at 2:24 pm
I’ve been wondering the same thing. Chased a few of these over the years and they are not fun. You start questioning your own knowledge.
MemberMay 26, 2020 at 4:01 pm
Working on getting the breaker upsized. Norlake is telling me that they recommend a 40 amp breaker but the unit data sticker says M.O.P of 35 amps so we can’t put anything bigger due to code. So now I’m trying to get Norlake to find a official document about it belonging on a 40 amp instead of a 35 amp
MemberMay 29, 2020 at 5:07 am
One never designs a electrical circuit for full load. It can be quite confusing to read the NEC code book, but depending on the load the breaker will be so that the load is 60 to 80 percent. That would mean a 42 amp breaker. If it’s a long run from the panel, you have to consider induction losses. With AC current, as the electrons flow one way they make a magnetic field. As they reverse they make a opposing magnetic field. They fight each other in the cable and use a small bit of energy. You can actually see a voltage drop when you have over 300 feet of run. That’s why the panel breaker is always bigger than the unit current protection.
MemberJune 21, 2020 at 4:29 pm
So we finally have a multi point fix. We had an new electrician come in and see what he could find. There is a leakage to ground from a couple of RTU on the panel, but that is around 1/2V so nothing that would explain the GFCI breakers tripping. What we were able to do for upsizing the breaker was, we put a 40 amp breaker in the panel for the cooler/freezer unit and put 35 amp fuses up in the disconnect. This got us around the M.O.P on the sticker of the unit because even though the breaker is 40 amps nothing over 35 amps is getting by the fuses. This should keep our other GFCI breakers from tripping if the surge was coming from the cooler/freezer.
There is a possibility the issue was from 2 faulty defrost clocks that we were able to replace with enclosed ones from Norlake. To help narrow down where the power surge is coming from the electrician wired in fuse blocks to the compressors and defrost heater circuits with fuses just over what that equipment needs. This way if it wasn’t the defrost clocks we will know what part of the unit is sending the surge.
Thanks for all that took the time to try and help us figure this out. So far it has been 2 weeks since I put the new timers in and we have not had an issue yet but I still wanted to proceed with the fuse blocks incase that wasn’t the issue and then we know right away and don’t need to screw around with all this again.
MemberJune 21, 2020 at 4:34 pm
Happy to hear there might be a light at the end of the tunnel.
MemberJune 22, 2020 at 7:50 am
There is a leakage to ground from a couple of RTU on the panel, but that
is around 1/2V so nothing that would explain the GFCI breakers
You have to remember that a GFI works from milliamps. They vary in spec from 5 to 8 ma, depending on application. So if you have a .5 amp potencial, it can easily trip a GFI.
But it sounds like your new electrician has a hand on it. BTW, fuses and breakers designed for HVAC are a slow blow to compensate for the high motor starting current. Seventeen times full run current.
Again, glad to hear you have a solution at hand.
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