OCPD and circuit for non-typical equipment.

[mjmike]

why do you want a 20A versus a 15A OCPD?

Spare capacity and other reasons.

 

[mjmike]

The definition of Branch Circuit is "The CIRCUIT CONDUCTORS between the final overcurrent device protecting the circuit and the outlet(s)."

210.20(C) sends you to 240.3 so that you don't ignore the equipment protection when sizing branch circuit OCPD. And 240.3 sends you to Art 210 so that you don't ignore the branch circuit conductor protection when sizing OCPD for equipment. I think its a CYA thing. But the equipment is not part of the branch circuit.

Ok, I see your point. I have to think about that. so, where do you then go to calculate the OCPD for a piece of equipment, if other than an appliance?

 

[david luchini]

Ok, I see your point. I have to think about that. so, where do you then go to calculate the OCPD for a piece of equipment, if other than an appliance?

Wherever 240.3 directs you. EG, Art 440 for Air conditioning, Art 630 for electric welders, Art 450 for transformers, etc.

 

[petersonra]

Spare capacity and other reasons.

What spare capacity? Are you thinking they may add some other piece of equipment to it down the road?

Are you allowed to feed two pieces of equipment off the same branch circuit?

 

[kaichosan]

I recently completed an upgrade to a WTP, and it's "on line" two years ago. We had 20.5kV UV (20 units). I just used the mfr's rating with a 40A service to each unit.

In your situation, 20A is OK. You're providing the required power and the 20A circuit breaker, 480V, 3PH is used to protect the feeder cable. (Just like you provide 20A, 120V, 1PH to your hardwired ceiling lights.)

 

[mjmike]

I recently completed an upgrade to a WTP, and it's "on line" two years ago. We had 20.5kV UV (20 units). I just used the mfr's rating with a 40A service to each unit.

In your situation, 20A is OK. You're providing the required power and the 20A circuit breaker, 480V, 3PH is used to protect the feeder cable. (Just like you provide 20A, 120V, 1PH to your hardwired ceiling lights.)

That is a large UV system there. I guess you had SCC and an HSC as well? What in the code did you use to base the circuit size on for your UV banks?

How do you know the 20A circuit is ok, what code reference? This is the part I am struggling with. What in the code says how to size the OCPD if it is not a piece of equipment listed in tablke 240.3. Is it indeed an appliance after all?

 

[mjmike]

Wherever 240.3 directs you. EG, Art 440 for Air conditioning, Art 630 for electric welders, Art 450 for transformers, etc.

Ok, we keep going around with this. My equipment is not a piece listed on tabe 240.3 hence where do you go from there, must it be one from the table that best fits? Then, would it indeed be an appliance as a "best fit".

 

[david luchini]

Ok, we keep going around with this. My equipment is not a piece listed on tabe 240.3 hence where do you go from there, must it be one from the table that best fits? Then, would it indeed be an appliance as a "best fit".

OK, let me try this...You have this piece of UV disinfection equipment.

1) Is it "utliization equipment"...Yes, it uses electric energy for a specific purpose.

2) Is it built in standardized sizes and types...Yes

3) Does it perform one or more function...Yes, it disinfects.

Looks like you have an appliance.

 

[petersonra]

OK, let me try this...You have this piece of UV disinfection equipment.

1) Is it "utliization equipment"...Yes, it uses electric energy for a specific purpose.

2) Is it built in standardized sizes and types...Yes

3) Does it perform one or more function...Yes, it disinfects.

Looks like you have an appliance.

however, the basic definition of appliance specifically excludes most industrial equipment. How do you get past that?

I think that this is a piece of equipment that just is not easily shoehorned into any of the categories listed. I think that using the guidelines for appliances makes the most sense, even if it is not actually an appliance. The only other thing that it would be is a luminaire. look closely at the definition of luminaire and then compare a typical UV disinfection system to that definition. I think luminaire is a closer fit than appliance.

The place I used to work used a lot of them and I think they all had built in OCPD as part of the UV system.

 

[david luchini]

however, the basic definition of appliance specifically excludes most industrial equipment. How do you get past that?

I think that this is a piece of equipment that just is not easily shoehorned into any of the categories listed. I think that using the guidelines for appliances makes the most sense, even if it is not actually an appliance. The only other thing that it would be is a luminaire. look closely at the definition of luminaire and then compare a typical UV disinfection system to that definition. I think luminaire is a closer fit than appliance.

The definition of appliance say "equipment, generally other than industrial..." A UV disinfection unit could be used in industrial, commercial, residential. There is nothing specifically "industrial" about this type of equipment.

I don't think "luminaire" quite fits the bill, because the equipment is not a "lighting unit," it is a "disinfection unit."

 

[petersonra]

The definition of appliance say "equipment, generally other than industrial..." A UV disinfection unit could be used in industrial, commercial, residential. There is nothing specifically "industrial" about this type of equipment.

I don't think "luminaire" quite fits the bill, because the equipment is not a "lighting unit," it is a "disinfection unit."

However in this case it is a piece of industrial equipment. You are trying to parse words to make your argument, when the plain language of the definition is what should be looked at first.

This is the NEC definition of luminaire:

Luminaire. A complete lighting unit consisting of a light
source such as a lamp or lamps, together with the parts
designed to position the light source and connect it to the
power supply. It may also include parts to protect the light
source or the ballast or to distribute the light. A lampholder
itself is not a luminaire.

That sure as heck is a lot closer to a typical UV unit than the definition of appliance. keep in mind there is no definition of lighting unit that I can find in the code so the only one that makes sense is some kind of "unit" that includes lamps of some sort. For those who would argue that UV light is not light, are not UV grow lamps considered to be luminaires? The only difference with a UV disinfection system is that the light is directed into water and not air.

Are UV lights that are used for disinfection of air streams not considered luminaires as opposed to disinfection units? Besides, there is no NEC definition of disinfection unit.

In any case, I don't think it makes much difference. Size the OCPD at 125% and be done with it. I am really surprised that the unit does not have OCP built in.

 

[david luchini]

However in this case it is a piece of industrial equipment. You are trying to parse words to make your argument, when the plain language of the definition is what should be looked at first.

I'm not parsing words, I'm looking at the plain language of the definition. It says "Utilization equipment, GENERALLY other than industrial..."

The definition does NOT exclude ALL industrial equipment from being appliances. Nor does the code define what "industrial utilization equipment" is, although it does define "industrial machinery." Nor does the code define what an "industrial installation" or an "industrial occupancy" is, although it does define a "supervised industrial installation."

Nor does the code say that all equipment that is installed in an "industrial installation" must be considered "industrial" utilization equipment. Even if you wanted to consider the disinfection equipment as "industrial equipment" because it is installed in an industrial occupancy, the plain language of the definition of "appliance" does not exclude that piece of equipment from still being an "appliance."

That sure as heck is a lot closer to a typical UV unit than the definition of appliance. keep in mind there is no definition of lighting unit that I can find in the code so the only one that makes sense is some kind of "unit" that includes lamps of some sort. For those who would argue that UV light is not light, are not UV grow lamps considered to be luminaires? The only difference with a UV disinfection system is that the light is directed into water and not air.

Are UV lights that are used for disinfection of air streams not considered luminaires as opposed to disinfection units? Besides, there is no NEC definition of disinfection unit.

In any case, I don't think it makes much difference. Size the OCPD at 125% and be done with it. I am really surprised that the unit does not have OCP built in.

I don't agree that the UV disinfection equipment fits the definition of luminaire better than appliance. I think the definition of luminaire and Art 410 are pretty clear that luminaires are for "lighting installations", that is to say visible lighting. Wouldn't an infra-red heat lamp also be a "luminaire" by definition? But Art 422 makes it pretty clear that it is an appliance. How about in a hospital, would you apply the Lighting Load Demand Factors to UV disinfection equipment?

It is true that the Code doesn't define "lighting unit" or "disinfection unit," nor does it define "motor control unit," "fuse unit," "panel unit," or "fixed electric space heating unit," but the Code uses all these terms. Even without a definition for each of these "units," I think we can identify what they are based on their function.

 

[kaichosan]

That is a large UV system there. I guess you had SCC and an HSC as well? What in the code did you use to base the circuit size on for your UV banks?

How do you know the 20A circuit is ok, what code reference? This is the part I am struggling with. What in the code says how to size the OCPD if it is not a piece of equipment listed in tablke 240.3. Is it indeed an appliance after all?

I deal with a lot of one of kind equipment installation in the silicon valley area. My approach is to provide power for each equipment using the requirements of the manufacturer...basically, amperage rating of the equipment x 1.25 and use appropriate feeder to handle the load. I also do a cursory look at their schematic for internal protection (N.E.C. n/a) and if it's a large load, discuss the peaking load, other transient starting possibilities, and harmonics contribution if applicable.

Sorry, we try to standardize at 20A breakers as a minimum size ...but as you pointed out you can use 15A 3PH breakers.

If you are worried about the application of NEC...discuss it with the building department.