Rules governing addition of components to an unlisted assembly

[gecco]

I am consulting for an industrial client and handling the project management which entails conducting contractor pre-bid meetings. During a recent walk-through I pointed out an existing enclosure and advised the electricians to use it to install two new VFD's and components. One of the electricians protested stating that if they were to install more than 8 components to that existing enclosure it would have to be recertified by UL or else the local AHJ would not pass the installation. My dilemma is that the existing installation (enclosure with one VFD, fuse block, contactor, line and load reactors, etctera) was never 'listed' in the first place, it was built on site by the client's personnel. My way of thinking leads to me say that as long as all the components are 'listed' and the work is done in accordance to the NEC by qualified personnel then we can add the new VFD's and components. I know it's going to come down to the local AHJ but I'd like to make a case at least. Can someone give me some direction? As a plan 'B', what's the difference of mounting components in the enclosure versus mounting them on the wall on a piece of din rail? The room is dedicated to VFD mounting and is only accessible to qualified personnel. The installation would be under engineering supervision as well.

Thanks..

 

[iwire]

Check out NEC article 409.

 

[petersonra]

It will be less expensive to just have a new enclosure built that is already UL listed.

 

[gecco]

Less expensive than.....keeping the enclosure and VFD that's there? I'm not overly concerned with the costs but that seems to be the cheapest route. Also, I need to leave the current VFD in service while doing the addition so I am trying to avoid having to replace it or disconnect it to relocate it. By definition of an industrail control panel, if I remove the components from the enclosure do I even have to label at that point? If the local AHJ is unreasonable then it may prove to be the easiest way to resolve any issues as well.

I've been through 409 and the only useful thing I have picked up is that the enclosure needs to be labelled correctly. It references the UL standards but doesn't say that industrial control panels must be listed or approved by UL. Makes sense since it doesn't take a genius to build a panel in a safe manner. I worked for a panel shop in college and it's a piece of cake. What am I missing?

 

[petersonra]

There are a bunch of things here.

Panel shops often can get parts for a lot less than you can.

There is far less labor when you build a panel in a shop by people who do this routinely than using electricians in the field to do it.

You can screw around a lot to try and do what you initially set out to do but the time and aggravation factor is probably not worth it.

Who is doing the drawings?