UL Question 1

[wbd]

Hello,

I have run into the following situation while modeling an industrial facility. In this facility there are power factor correction units located throughout the facility, usually off of major panels. This is at 480V. Here are the issues uncovered as part of data collection and building the model:

1. The manufacturer's nameplate lists the fault duty of the power factor correction devices as 18kA. However, inside of the unit is a main circuit breaker that is rated at 480V, 10 kA. This would then make the unit rated at 10 kA, not 18 kA as stated on nameplate.

2. In one power factor correction unit, a main breaker rated at 240V (this is 480V system), 5 kA was found.

My concern is that these are UL listed devices, so:

1. Is there an obligation to report this to UL?

2. If so, who is obligated, myself as the PE or the owner of the equipment?

3. If the 10kA rating is not suitable for the installed application and the internal breaker is changed out to a higher rating one, what does one do about the rating indicated on the manufacturer's nameplate? Can it be legally changed?

 

[MacGyverS2000]

I'm not a power guy or a PE, so take this with a grain of salt...

1) If the company is substituting parts against their UL certification, I imagine UL will want to decertify the equipment in their logs. Whether or not they want to be contacted about this or wish to find out themselves during the standard check is unknown to me...

2) As a PE, I believe you have a moral (and possibly legal) obligation to report any potential hazards. The owner of the equipment may have a lesser amount of same...

3) I imagine the breaker can be changed out for something no higher than as labeled... this obviously assumes the company did not modify more internals to the box making a larger breaker dangerous (i.e., internals are not actually capable of handling higher than a 10kA).

Dan - Owner

http://www.Hi-TecDesigns.com

 

[dpc]

The 10 kA breaker does not necessarily mean the overall 18 kA rating is not valid. If there is a UL label and a factory nameplate on the entire assembly indicating that the short circuit rating is 18 kA, I think your responsibility ends there, although you could certainly call the supplier to verify.

Combination motor starters using circuit breakers used to be routinely rated for 22,000 A or 25,000 A even though the breaker was only rated for 14,000. This was based on UL testing of the assembly as a whole. With the added impedance of the other components, and the way UL defined the test requirements, the higher rating was considered valid.



David Castor

http://www.cvoes.com

 

[wbd]

Thank you. The thing that bothers me is that the manufacturer has said that the rating is 10kA, even though the nameplate says 18 kA. I am still trying to get a definitive answer.

These are manufactured in Canada and I am not familiar with Canada regs and standards, so there may be some confusion on my part there.

 

[jraef]

The thing that bothers me is that the manufacturer has said that the rating is 10kA, even though the nameplate says 18 kA. I am still trying to get a definitive answer.

If they are confused then that is not a good sign. But are you talking to a product engineer or an inside salesperson?

If the rating is different than the rating they CLAIM it is, then you would report it to UL. So in your point #2 for example, if their nameplate stated it was rated for 480V and they used a breaker inside that is only rated fr 240V, they they have most likely violated their UL listing (assuming they have it). But if they state it is 18kA and the breaker does not appear to you to have that high of a rating, then as dpc said, that does not immediately mean they have done anything wrong. They may have tested the entire assembly at 18kA even with the 10kA rated breaker and if it passed, it passed.

One possible explanation exposes a dirty little secret in the breaker industry. In some cases where a breaker mfr has two IC ratings on the same frame (i.e. 18kAIC and 22kAIC), in reality they only manufacture one. All of them are made to the higher rating because it's too expensive to maintain two product lines. So the breakers are the same but the labels are different and if they can get away with charging you more for the higher rating, they do. But when you go to test an assembly and use the cheaper version, it still passes at the higher rating...

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