ELECTRICAL WIRING FOR FREEZERS
PLEASE NOTE: A licensed electrician should be retained and used to wire any circuits supplying power to a commercial freezer. Severe and permanent damage will result from improper wiring of your freezer!
Recently I have had several issues from improper wiring of freezers including individuals who have cut the factory plug off of the unit exchanging it for a different plug. In most cases, I get a call from the customer complaining that the unit is not working. The implication is I sold a bad unit when in every single case, the customer improperly wired the unit. Unfortunately, in several cases, serious and costly damage was done to the unit. For this reason, it is apparent my customers need a source of information to ensure they don't experience wiring issues.
WHAT IS THE ELECTRICAL REQUIREMENTS FOR MY MERCHANDISER?
It is imperative to check the voltage and amp draw to determine proper line and fuse or circuit breaker size. This information is obtainable via the Data Platefound inside the unit.
Check power supply for low voltage. If voltage reads "230" with no load, and it drops below "207" when the compressor tries to start, it is an indication of too small of a supply wire or possibly too long of a run.
It is imperative that a separate circuit be run for each cabinet to prevent another appliance blowing the fuse of breaker, or loss due to low voltage from an overloaded circuit.
WHAT IS THE PLUG TYPE NEEDED FOR A FREEZER?
Most 2 and 3-door self contained (low temp) freezers will have and come with a NEMA L14-20P twist lock plug. This is a 20 amp plug but interestingly reads 125/250 volt on it. The cabinet must be grounded.
CAN THIS PLUG UTILIZE A 3 WIRE SYSTEM?
The quick and simple answer is NO! Most manufacturers have a 4-wire system. There should be a red wire and a black wire (power legs - hot), a white wire - which is the neutral, and a green wire - which is the ground. The ground will have a "L" shape to it on the plug configuration. It is important to note; when wiring the plug, the "L" shape - ground leg is the green wire, the opposite leg will be the white - neutral leg. The other two legs will be the "hots" - black and red.
CAN I WIRE THE NEUTRAL TO THE GROUND?
Although it is possible and the unit should still work. DO NOT DO THIS! By wiring the neutral and the ground together, it eliminates the use for the run capacitor and will cause and create "hard" starts for the compressor. This will reduce the life of the compressor and reduce.
*NOTE: I have just recently experienced a couple of clients who have indirectly encountered this. Although my client hired a licensed electrician and informed him what I mentioned regarding the requirements of the unit, the electrician, in the breaker panel, wired the ground and neutral into the ground bar - he did not separate them for reasons I cannot explain. And, in this case, the first unit tanked the compressor as well as the replacement unit I brought them. IT IS IMPERATIVE TO KEEP THE GROUND AND NEUTRAL ISOLATED AND SEPARATE!
QUESTIONING THE MASTER...
I recently had a conversation with a friend who is a retired Master Electrician regarding wiring issues I have encountered...
The Freezer Depot: Is it ok to wire the neutral and the ground together on a 230/208 volt system?
Master Electrician: chuckles...I don't know why anyone would do that. It is against code and is a safety hazard.
The Freezer Depot: Why is it a safety hazard, what are the ramifications?
Master Electrician: First off, it is dangerous tying these together because if the neutral is lost, potentially the ground could carry current and become a conductor. You see, the neutral can actually carry current whereas the ground does not. If the ground ends up carrying a current, anything or anyone that touches it can ultimately become "grounded" and subsequently be electrocuted.
The Freezer Depot: Assuming no one gets electrocuted, and the system is clearly functioning with this improper wiring, what ill effects does this have on the motor / compressor?
Master Electrician: The windings inside the motor will get super hot when operating. It is possible when the unit cycles off (on temperature or defrost), this will create or develop "heat / cold" cycles which destroys the windings. This also may occur if there are inconsistent voltage drops such as time of day occurrences or other equipment fed from the same panel or sub-paneling cycling at the same time.
*NOTE: In a separate conversation with an engineer from True Manufacturing, the engineer informed us: "when the neutral and ground are shared or wired together, this eliminates the usage of the run capacitor." When asked what that means, we were told, the run capacitor actually stores voltage which helps the compressor to start - it is like a boost of stored voltage which assists the compressor at start up thus making it easier to start. Without the run capacitor and the boosted voltage, the compressor will "hard start" on it's own thus requiring more voltage and greater amperage and voltage draw. This will work, for awhile, but certainly will have adverse effect on the compressor including longevity and undue unnecessary wear and tare.
The Freezer Depot: I have had customers state that the panel or sub panel only has the 2 hots and 1 neutral bar thus thinking they have no other option then hooking the neutral and ground to this lone neutral bar. What do you recommend in this scenario.
Master Electrician: It sounds to me that those scenarios are referring to "older" panels. The ones we are installing today have both a neutral and ground bar on opposite sides of the panel. If the panel only has one bar, I see no issues utilizing a ground rod for the panel itself or for the unit to be wired as the grounding source. I would first check with local code or the electrical inspector and see what he recommends.
*NOTE: it is imperative for the customer to know the requirements of the merchandiser they are purchasing. Please contact the manufacture for an owners manual - most have these available on-line and all offer these for free. Also - hire a licensed electrician if you are running a new circuit or even to test the one you currently have.