OCPD and circuit for non-typical equipment.

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mjmike

Senior Member
I have a piece of UV disinfection equipment at a treatment facility we are designing the electrical connections to. We provide a single point connection to the equipment power terminals. The load is say 5KVA power draw and 480V 3-phase voltage. The equipment does not have a local overcurrent protection device and is to be provided by the others. Hence we need to note the breaker / circuit size. The manufacturer does not indicate the required overcurrent protection size (asked them). Hence, would the circuit be designed per article 210.20(C), which would then take us to table 240.3. Per the table, would this be a branch circuit or an Industrial machine?

If a branch circuit, we are back to 210.20(A). Now we need to ask the question if the load is continuous or not. Regardless, both would calculate out to be a 15A breaker (smallest breaker size) and conductors. Would still specify #12 conductors though. However, this would be the minimum size. What determines the maximum? Since the manufacturer did not provide any input on the OCPD, what would keep us from noted a 20A or even a 50A circuit?

If this would be considered an industrial machine, article 670 is now in play. However, there does not appear to be any motors, just UV lamps. 670.4(C) notes if no protection is provided with the machine, refer to 430.52 and 430.53. However, this may not be applicable since we don?t think there are motors. Even if there are, all we know is the manufacturer noted the load as being say 5KVA power draw.

Not sure what direction to proceed.
 

mjmike

Senior Member
I'd say you have an "appliance" (Art. 422.)

Per 422.11(E)(2), it can be on a 20A (or smaller) branch circuit.


Thanks, but I ruled it out as being an appliance based on the definition of an appliance. This is more of an industrial piece of equipment. I would say it could even have a small motor in it. Only know the load provided by the MFGR. Manybe generalize more as to not knowing if there are motors or not, only given load info.
 

G._S._Ohm

Senior Member
Location
DC area
An online manual for the machine may show a schematic.

If you have a scope & shunt you can look for initial inrush current. Also check the PF. If none & 1.0 respectively, then sizing a breaker should be easy.
 
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dicklaxt

Senior Member
If you have a 5 KVA load as a given why would you want to do anything other than 20a & #12,,,thats what I'd go with,,

dick
 

david luchini

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Thanks, but I ruled it out as being an appliance based on the definition of an appliance. This is more of an industrial piece of equipment. I would say it could even have a small motor in it. Only know the load provided by the MFGR. Manybe generalize more as to not knowing if there are motors or not, only given load info.

Art. 670 requires that an industrial machine include a permanent nameplate that tells: Max ampere rating of the short-circuit and ground fault protective device; ampere rating of the largest motor; supply voltage, number of phases, full-load current...

Your original post said there were no motors, just UV lamps. Your second post indicated there may be a small motor?!?! Which is it? What "material" is being processed by this machine?

If this was an Industrial Machine, there would be a nameplate telling you the max. OCPD. The definition of "Appliance" is awfully broad, and the equipment you described certainly sounds like it would fit the bill. By the way, if there is a motor, look at 422.11(G) instead of 422.11(E).
 

mjmike

Senior Member
If you have a 5 KVA load as a given why would you want to do anything other than 20a & #12,,,thats what I'd go with,,

dick

I am concerned the 20A circuit may be too high. 1st available breaker would be 15A. I actually asked the mfgr is a 20A circuit was ok and their response was "size as per local code".
 

mjmike

Senior Member
UV disinfection is usually just a light. I would give it a 20A branch circuit and not worry anymore about it.


I am concerned the 20A circuit may be too high. 1st available breaker would be 15A. I actually asked the mfgr is a 20A circuit was ok and their response was "size as per local code". So where do I go from there?
 

mjmike

Senior Member
Art. 670 requires that an industrial machine include a permanent nameplate that tells: Max ampere rating of the short-circuit and ground fault protective device; ampere rating of the largest motor; supply voltage, number of phases, full-load current...

Your original post said there were no motors, just UV lamps. Your second post indicated there may be a small motor?!?! Which is it? What "material" is being processed by this machine?

If this was an Industrial Machine, there would be a nameplate telling you the max. OCPD. The definition of "Appliance" is awfully broad, and the equipment you described certainly sounds like it would fit the bill. By the way, if there is a motor, look at 422.11(G) instead of 422.11(E).

Very good point. on the nameplate. If there were a nameplate, the MFGE wouldn't have told me to size per local code. So, I would rule out article 670, thanks. Now would this be just a branch circuit? If so, what would tell me the maximum amperage allowed? I know the min breaker would be 15A, but what would be the maximum? What would allow a 20A circuit?
 

mjmike

Senior Member
Thanks for the info.

I am also thinking to size the circuit per 210.20(A) as a MINIMUM. Since the manufacturer does not denot the MAXIMUM OCPD for a safe install, 20A circuit and OCPD would be incompliance with the code.
 

david luchini

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Staff member
Location
Connecticut
Occupation
Engineer
I am also thinking to size the circuit per 210.20(A) as a MINIMUM. Since the manufacturer does not denot the MAXIMUM OCPD for a safe install, 20A circuit and OCPD would be incompliance with the code.

I don't follow what you are saying.
 
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mjmike

Senior Member
I am saying, per 210.20(A), this would be the minimum rated OCPD. However, there is not a calculation for the maximum.

I believe the MFGR should indicate the maximum for safe operation.

I still am in dis-agreement UV disinfection equipment is an appliance in an industrial application although I like the 422.11 reference. I would think it is a branch circuit per table 240.3.
 

petersonra

Senior Member
Location
Northern illinois
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engineer
I am saying, per 210.20(A), this would be the minimum rated OCPD. However, there is not a calculation for the maximum.

I believe the MFGR should indicate the maximum for safe operation.

I still am in dis-agreement UV disinfection equipment is an appliance in an industrial application although I like the 422.11 reference. I would think it is a branch circuit per table 240.3.

Are you telling us there is no information from the manufacturer that says what the current draw of the system is? If there is than use that information to size the OCPD.

There is no requirement that a manufacturer of the type of equipment you are describing tell you what size OCPD to use, or a min or max size OCPD.

Appliance. Utilization equipment, generally other than industrial,
that is normally built in standardized sizes or types
and is installed or connected as a unit to perform one or
more functions such as clothes washing, air conditioning,
food mixing, deep frying, and so forth.

The definition of appliance would seem to exclude this equipment from being an appliance.

210.20 (C) Equipment. The rating or setting of the overcurrent
protective device shall not exceed that specified in the applicable
articles referenced in Table 240.3 for equipment.

I don't see anything in the list of stuff in table 240.3 that would appear to directly apply other than article 410 (luminaires).
 
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david luchini

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I am saying, per 210.20(A), this would be the minimum rated OCPD. However, there is not a calculation for the maximum.

Yes, 210.20(A) will tell you the minimum rated OCPD. The minimum OCPD rating would depend on continuous vs. non-continuous. The minumum c/b size would be 15A, but using fuses, it would be 6A (for a non-continuous load.)

I believe the MFGR should indicate the maximum for safe operation.

In this case, the manufacturer hasn't indicated a maximum OCPD for safe operation. But the code addresses the case where the OCPD rating is not marked, so its fine to follow what the code says.

I still am in dis-agreement UV disinfection equipment is an appliance in an industrial application although I like the 422.11 reference.

Whether or not its in an industrial application doesn't change whether the equipment is an appliance. The UV disinfection equipment doesn't fall into any of the other types of equipment listed in 240.3. And it does meet the definition of appliance.


I would think it is a branch circuit per table 240.3.

The Branch Circuit per table 240.3 refers to the CONDUCTORS, not to the equipment. An appliance would be connected to a branch circuit. Both the conductors and the equipment must be protected.
 

mjmike

Senior Member
Are you telling us there is no information from the manufacturer that says what the current draw of the system is? If there is than use that information to size the OCPD.

There is no requirement that a manufacturer of the type of equipment you are describing tell you what size OCPD to use, or a min or max size OCPD.



The definition of appliance would seem to exclude this equipment from being an appliance.



I don't see anything in the list of stuff in table 240.3 that would appear to directly apply other than article 410 (luminaires).

Thay are giving the load, and saying to size the OCPD per the local code. I can use this to get the minimum based on 210.20(A), but nowhere can I figure out the maximum and the manufacturer won't say. I calculate the minimum to be 15A, but would prefer to provide a 20A circuit.
 

mjmike

Senior Member
Yes, 210.20(A) will tell you the minimum rated OCPD. The minimum OCPD rating would depend on continuous vs. non-continuous. The minumum c/b size would be 15A, but using fuses, it would be 6A (for a non-continuous load.)



In this case, the manufacturer hasn't indicated a maximum OCPD for safe operation. But the code addresses the case where the OCPD rating is not marked, so its fine to follow what the code says.



Whether or not its in an industrial application doesn't change whether the equipment is an appliance. The UV disinfection equipment doesn't fall into any of the other types of equipment listed in 240.3. And it does meet the definition of appliance.




The Branch Circuit per table 240.3 refers to the CONDUCTORS, not to the equipment. An appliance would be connected to a branch circuit. Both the conductors and the equipment must be protected.



I am confused about the last statement. 210.20(C) is for equipment overcurrent protection referring to 240.3 which is overcurrent protection for equipement. Hence, one of the categories is "branch circuits" similarly as "appliances" is a category. So I am saying branch circuit per table 240.3 referrs the the equipment and the conductors connected to the branch circuit per 210.20.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Thay are giving the load, and saying to size the OCPD per the local code. I can use this to get the minimum based on 210.20(A), but nowhere can I figure out the maximum and the manufacturer won't say. I calculate the minimum to be 15A, but would prefer to provide a 20A circuit.

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

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
I am confused about the last statement. 210.20(C) is for equipment overcurrent protection referring to 240.3 which is overcurrent protection for equipement. Hence, one of the categories is "branch circuits" similarly as "appliances" is a category. So I am saying branch circuit per table 240.3 referrs the the equipment and the conductors connected to the branch circuit per 210.20.

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.
 
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