NEC 440 do i need a fuse disconnect

[purevoltage]

Hello all
I was asked to look at this disconnect on the roof. it serves a HVAC package unit which I have put the name plate on here so you can see what it says. This is a non fuse 400amp horse power rated disco. Fed from the basement with a 350 amp breaker.440.21 General
The provisions of Part 3 specify devices intended to protect thebranch-circuit conductors, control apparatus, and motors in circuits supplyinghermetic refrigerant motor-compressors against overcurrent due to shortcircuits and ground faults. They are inaddition to or amendatory of the provisions of Article 240.
Whatdoes this mean?
Wherean air conditioner is listed by a qualified electrical testing laboratory witha nameplate that reads “maximum fuse size,” the listing restricts the use ofthis unit to fuse protection only and does not cover its use with circuitbreakers. If the air conditioner hasbeen evaluated for both fuses and ordinary circuit breakers or both fuses andHACR-type circuit breakers, it is marked to indicate the acceptable type(s) ofprotective devices.
This is out of the 2014 hand book. I called the manufacture to see what they require. They said if I bought this HVAC package unit from them then they would have sent a fuse disco with it. but if field wired they would say do what ever the AHJ says. As you can see there is a rope holding this disconnect from falling over because the roof support no longer is holding it in place. If we were going to have to go through the work of replacing the disco I wanted to make sure we put the right one in. 440.12 (B)(2) exception: a listed unfused motor circuit switch, without fuse holders, having a horsepower rating not less than the equivalent horsepower determined by 440.12(B)(1) shall be permitted to have an ampere rating less than 115 percent of the sum of all currents. does this code allow the disconnect installed now to be ok? or does it need to be a fused one? also the bottom of this disco has all the KOs busted and the conduits just stick in the disco.

Any thoughts on this?

 

[dkidd]

The nameplate says to use fuses. The size depends on the voltage.

 

[jap]

Is fusing the reason they asked you to look at it or to get an opinion on all of the KO's being KO'ed?


JAP>

 

[augie47]

The nameplate says to use fuses. The size depends on the voltage.

:thumbsup:
Follow the nameplate requirements (300 or 350 amp RK5 or others types listed)

 

[purevoltage]

Jap
No I went to look at it because it is being held up with a rope. If you zoom into the pic you can see it. Sorry the pic is so small.
I do have another question. If the equipment itself has fuses would that constitute being fused? I have not seen that part of the machine yet but if there was something there would that satisfy the requirement to have fuses?

 

[kwired]

What is the * on the nameplate next to the line requiring fuse protection all about?

I see another * higher up, is it possible fuses are required per CSA listing but not UL?

 

[iwire]

If the equipment itself has fuses would that constitute being fused?

No.

The nameplate tells you to use fuses so you must use fuses in the supply at some point.

 

[purevoltage]

Thanks for the input. I do have another question. My electrician is telling me it was inspected at some point in the past. I have no record of this and he can not produce a record of this ether. If it was inspected do think the inspector was unaware of the code for this piece of equipment and let the disco pass. Or maybe he saw a disco and assumed that it was fused. Not sure what to say to that. I have looked at our local codes and have not found anything that would over ride the code at this point. I know there is a meeting coming and I want to have myself ready for answers to the objections to replacing the disco. At least make aware of the reasons why the inspector could have passed it. I don't think it was inspected. A lot of installs are just flown in and no inspection. Im trying to change that being the administrator for our campus.
Any thoughts on this? again thanks for the input.

 

[kwired]

I still think the fuse requirement only applies to either the UL standard or the CSA standard, but it is not clear which. I only say this because they have an * between the two standards higher up on the label, then have * in front of the line that states fuse protection.

Best guess is CSA standard requires fuses. Tried to look at both standards online but really haven't determined anything related to this from what I have seen.

 

[jap]

My thoughts are, if your planning on repairing it, put in a fused disconnect.
I wouldn't remove and replace it for the simple fact that it doesn't have fuses.
If I walked up on this, how would I ever know that the unit may have been replaced at some point and the original unit didn't require fused protection?


JAP>

 

[augie47]

From the looks of the mounting and knockouts I hope it was not inspected
In originally stated "fuse required" but feel kwired has pointed out a "loophole". I agree it is unclear if the " * " refers to UL or CSA but it is certainly possible that the unit might be listed under either agency for use without fuses and thus be acceptable to the AHJ.
The determination might well rely on manufacture literature and the specifics of the system. Although I would lean toward fuse protection, you would need to determine the supply SCA and equipment withstand ratings etc and apply NEC 110.10

 

[alive wire]

Okay guys, I don't want to hijack this thread but I ran into this with a house that I purchased AC had not been maintenance properly and the refrigerant had thickened according to the HVAC Tech to the point of overloading the compressor motor,using a fusible disconnect would have prevented the motor from overloading and burning up, so why would we not just always use them on any motorized equipment

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[alive wire]

With the exception of possibly of a vfd

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[GoldDigger]

Okay guys, I don't want to hijack this thread but I ran into this with a house that I purchased AC had not been maintenance properly and the refrigerant had thickened according to the HVAC Tech to the point of overloading the compressor motor,using a fusible disconnect would have prevented the motor from overloading and burning up, so why would we not just always use them on any motorized equipment

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It is hard to find a fuse that will allow the motor to start but will protect the motor against even a small overload.
What you need for motor protection is an overload device not an OCPD.

 

[kwired]

It is hard to find a fuse that will allow the motor to start but will protect the motor against even a small overload.
What you need for motor protection is an overload device not an OCPD.

I agree, and the unit likely had an overload device integral to the compressor.

Also never heard of refrigerant "thickening". Have heard of it being contaminated by a compressor that was failing anyway, or of plugged evaporator not allowing enough evaporation and liquid making it's way back to the compressor.

 

[alive wire]

It is hard to find a fuse that will allow the motor to start but will protect the motor against even a small overload.
What you need for motor protection is an overload device not an OCPD.

Thanks Golddigger and kwired

I agree, and the unit likely had an overload device integral to the compressor.

Also never heard of refrigerant "thickening". Have heard of it being contaminated by a compressor that was failing anyway, or of plugged evaporator not allowing enough evaporation and liquid making it's way back to the compressor.

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