Walkin Freezer Protection?

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solarEI

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I am working on a project that has walk-in coolers and freezers. I?m very confused about the code requirements for protection. The equipment submittals state that the 208V single phase evaporators are powered from the 208V three phase condensing units.

Nameplate for Freezer equipment is:
? Compressor = 11 RLA, 208V 3 phase, (2) Fans = .7A, 208V 1 phase each, MCA = 14.8A, Max fuse = 25A
? Evap nameplate states (3) fans = .45A (1/15hp), 208V 1 phase each, heater = 13A, MCA = 15A, Max circuit protection = 20A

The condensing units have hermetic refrigerant motor compressors so they fall under NEC 440. The evaporator motors do not have these compressors, so do they fall under NEC 430?

NEC 440.8 states a refrigeration system shall be considered to be a single machine and that the motors are permitted to be located remotely from each other, and references exceptions to 430.87 and 430.112 indicating (with conditions) that they can have a single controller and single disconnecting means. Does this mean a 3 phase fused disconnect ahead of the CU is sufficient, even though the evaporator is single phase with MOP = 20A? Or does the evaporator need a disconnect (with OCP) located within sight to satisfy the nameplate requirements?

If so, is a 25A fused disconnect per CU nameplate the proper size? That is the rating for the CU, but the evap has additional motors and a heater? What is the proper method of sizing the disconnect, MOP and circuit conductors for this situation?

The factory states the heater is used for defrost mode, in which case the CU is not running, however, the field technicians say they encounter breaker tripping issues because the CUs take a minute or so to shut down, so for a short while they are simultaneous.

Suppose a situation with slightly different equipment (evaps are still fed from CU). The CU requires max fuse = 25A but the additional loads of the evaporator calculate out to something more, say 40A (perhaps it has a larger heater), how do you size the protection for the single disconnect per 440.8?

Thanks!
 
Walkin Freezer Protection

Walkin Freezer Protection

SolarEI

The ones that I have done, the defrost heater is a different circuit.

So in your case you would have a disconnect at the evaporator for the fan (circuit 1) and a separate disconnect (circuit 2) for the defrost heater.

I also pull another circuit for my control voltage.
 
solarEI said:
The condensing units have hermetic refrigerant motor compressors so they fall under NEC 440. The evaporator motors do not have these compressors, so do they fall under NEC 430?

NEC 440.8 states a refrigeration system shall be considered to be a single machine and that the motors are permitted to be located remotely from each other, and references exceptions to 430.87 and 430.112 indicating (with conditions) that they can have a single controller and single disconnecting means. Does this mean a 3 phase fused disconnect ahead of the CU is sufficient, even though the evaporator is single phase with MOP = 20A? Or does the evaporator need a disconnect (with OCP) located within sight to satisfy the nameplate requirements?

If so, is a 25A fused disconnect per CU nameplate the proper size? That is the rating for the CU, but the evap has additional motors and a heater? What is the proper method of sizing the disconnect, MOP and circuit conductors for this situation?

Suppose a situation with slightly different equipment (evaps are still fed from CU). The CU requires max fuse = 25A but the additional loads of the evaporator calculate out to something more, say 40A (perhaps it has a larger heater), how do you size the protection for the single disconnect per 440.8?

Thanks!
Click to expand...

Nobody has comments in regards to the code application questions and protection sizing requirements?
 
For many of us it is a somewhat confusing situatio and, as noted, there are many different circuit configurations so the only "correct" answer will be your AHJs :D

From what I have seen, the freezers and coolers have been treated a bit differently.
On freezers, often there is one controller for compressors, evaporators and sometimes heaters. From my experience they usually have one disconnect per 440.8. The circuit and overcurrent protection is sized per the nameplate.
In your case, it appears your freezer requires a seperate circuits for the evaporator so, IMO, it would need to be sized per nameplate with its own disconnect

On the other hand, walk in coolers that I see often require a separate circuit for the condensers and evaporators. Each has its own nameplate to size the circuit and OCP device and each requires it own disconnect.
 
cowboyjwc said:
The sizing requirements are per the name plate listing. 440.6(A)
Click to expand...

I agree, once you have a name plate that shows the minimum circuit ampacity and the maximum permitted OCPD, you just have to look at the name plate and make your installation comply with that information.
 
What you need to do to wire this correctly really depends on where the defrost timer is located. If this is a factory matched set then there should be a wiring diagram. If not then more information is needed.
 
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