Nfpa70 409.30, nfpa79 5.3 & ul508a

[Brinkmann]

For a few customers we build control panels which are for groundwater remediation systems. They usually have an UL489 breaker or a disconnect, breakers for other equipment and control logic. We use a thru door disconnect for the main breaker.

Seeing this was too easy, a customer wanted a cable type disconnect with the handle on the enclosure not the door. This started me on the "door interlock" search on the forums. Of which I found many opinions as to whether they were need or not. If you look at NFPA 70, it bascially says go see UL508A. NFPA79 says you do with a few exeptions. From what I understand NFPA 70 and UL508A are rules, NFPA 79 is a suggestion.

UL508A says if it is a "General Use Industrial Control Panel" The is UL paragraph 30 (Disconnect Switches) doesn't require the interlock. But the handle must be able to be locked in the off position.

UL508A also has what it calls Part 2 - Specific Use Industrial Control Panels Types, starts at paragraph 62. This includes, Industrial Machinery, Crane Control, Service Equipment Use, etc.

Inside of Industrial Machinery, it lists Metalworking Machine Tools, Plastics Machinery, Wood Machinery, Assembly Machimes, etc. Equipment you would see at Coca Cola bottling plant or where plastic milk jugs are made.

UL at this point says the door interlock is required along with other panel changes. (internal wire size).

So, I try to determine what my panel is. I don't see it fitting into Industrial Machinery as we are not building or making anything. This, in my little mind, would put us into the "General Use" catagory. This logic would say the interlock is not required, the lock on the handle is.

Sorry for the long post......Any comments as to my logic?

Thanks

 

[Dave Garbrough]

NFPA 110 start up check list

NFPA 110 start up check list

Hi,
I'm looking for a checklist (if one's available) for a start up on a generator that must meet the NFPA 110 regs. Any help would be greatly appreciated. DG

 

[cycotcskir]

From http://www.ul.com/global/eng/docume...ors/2005_UL_IAEI_Inspector_Meeting_Report.pdf

Q.
Educating manufacturers on listing limitations. Can UL educate the manufacturers on limitations of their listings? For example, a manufacturer takes a listed equipment enclosure, then fills it up with components, and tries to pass it off as the whole product is listed. Another example is use of a general use Industrial Control Panel for a specific use, such as elevator control. When the AHJ does not approve the use of the product, the AHJ experiences considerable political pressure.
A.
The scope and limitations of a manufacturer?s product are stated in the Listing and the associated UL Guide Information. UL has developed a variety of educational courses for various industries, which are available through the UL University. UL?s representatives to the various industries are continually providing assistance and education to their respective industries. Also, UL provides specific training, as part of the condition of listing, to manufacturers of specific industries, including industrial control panels and electric signs. UL is continually working to provide AHJs with resources to enable them to do their job.

The UL doesn't like to give out many FREE answers in my experience. Although, I have talked with one man who was very accommodating.

Personally, I would think of this as specific use. It is not Industrial Machinery as you have listed, but it would seem to fall under "specific" due to the fact that it is being designed for a singular intended purpose with equipment intended for that use also. I also think that considering intent of manufacture is embarking on a bit of a gray murky unprovable area. Since you have readily admitted the intended purpose, coupled with the fact that it is for "a few customers" rather than mass produced, I would lean in the direction of specific use.

This may not be what UL would say, or anybody else for that matter. I may be wrong. It's been known to happen from time to time.:roll: This is how I would inspect this situation if it were in front of me, though.

However, the Table of Contents for 508A lists: Enclosures, Industrial Machinery, Crane Control, Service Equipment, Elevator Control, Flame Control, Marine Use, and Air Conditioning and Refrigeration Equipment. Since I don't have access to the whole document, I am not sure whether or not these section titles are meant to be an exhaustive list or are only meant to address a few of the most common instances that would fall within the "specific use" category.

If it is not a critical cost issue, I would say to err on the side of caution/overdesign. Being as anal as I am, I would still want to know where the line is, though.:grin: