NFPA 79 (2015) Machine Nameplate Data Question

[fifty60]

I have a question about 16.4.1(5), where it is required to display the "Maximum ampere rating of the short-circuit and ground fault protective device, where provided".

I am having trouble with the "where provided" part of this. Does this only apply if there short circuit protection is provided with the machine? If the equipment is intended to be permenantly connected, and the customer is to supply the disconnect and fusing, then can this information be omitted?

 

[fifty60]

Is this asking for the largest branch OCPD located within the equipment? Would this be so that the installation of the equipment overcurrent protection can be in compliance with NEC 409.21(C), or is it asking for the largest OCPD for the equipment based off of 409.21(C)?

Is NFPA 79 requiring that the information be provided so that the installer can make the calculation, or is it asking that the calculation be already made for the installer?

 

[mayanees]

I am having trouble with the "where provided" part of this. Does this only apply if there short circuit protection is provided with the machine? If the equipment is intended to be permenantly connected, and the customer is to supply the disconnect and fusing, then can this information be omitted?

I say yes and yes, based on the continuation of 409.21(C) which states that if a main ocpd is not provided then comply with 430.52 and 430.53 for determination of the rating of the feeder for the panel.

 

[petersonra]

I have a question about 16.4.1(5), where it is required to display the "Maximum ampere rating of the short-circuit and ground fault protective device, where provided".

I am having trouble with the "where provided" part of this. Does this only apply if there short circuit protection is provided with the machine? If the equipment is intended to be permenantly connected, and the customer is to supply the disconnect and fusing, then can this information be omitted?

I think they are referring to the cabinet main OCPD if it is provided as part of the machine. A fair number of larger CBs have adjustable settings so i think they are asking you to put the maximum setting or fuse size on the nameplate for some reason.

Many machine builders seem to ignore this suggestion.

 

[fifty60]

Petersonra, do you call it a suggestion since it is an NFPA79 requirement and not an NFPA70 requirement? If one were to follow 409.110 alone, I would not have to add the largest HP motor or load information or anything regarding a Max OCPD..

 

[fifty60]

If I want to list the largest motor FLA for a machine that has a refrigeration compressor as its largest motor, would I use the MOC of the motor?

Refrigeration compressors use RLA (Rated Load Amps) which is the amp rating under a controlled set of conditions. The compressor itself will draw above or below the Rated Load Amps depending on the compressor load. Is it safe to put the RLA on the nameplate of the machine, or would the Max Operating Current be what should be used on the nameplate largest motor FLA requirement?

The MOC is where the internal overload of the compressor is set. The running load of the compressor will never exceed this for any indefinite period of time.

I believe the only reason to list the largest motor FLA is so that the MAX OCPD can be calculated for the overall sizing of the main equipment OCPD. If this is the case, then I believe I should use the RLA of the motor since this is what the MAX OCPD would be calculate from (using NEC 440, RLA X 225%)