Hi, I've got a customer who loves adding branch circuits to their control panels. It is not unusual to have 5 or 10 additional branch circuits taken off a panel that has nothing to do with the control system. It also means anytime they would like to turn off a branch circuit or reset a circuit breaker. They would need to put the arc flash equipment on, as they are always exposed to live parts while exercising the circuit breaker with the open industrial control panel door. Short of best practice, is there any NEC or OSHA reg that would deter this practice and move to use a normal panel board?
Using and Industrial Control panel as a power panel
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Shaneyj
Senior Member
- Location
- Katy, Texas
- Occupation
- Project Engineer
I agree any alteration to the as built voids the certification.
I’m curious how they are adding. Pulling off existing OCPD? Pulling off a power bus? Fuses or breakers. If breaker are they UL489 or 1077?
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
What code prevents it from being altered?
IMO, 110.3(b)
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
That is a serious stretch.
Agreed. I don't think that prevents listed equipment from being altered in a blanket statement kind of way.
However, altering listed equipment (most likely) voids any listing/certification/warranty. And then if that equipment is required to be listed, now you have a problem because of that... but I don't see 110.3(b) as preventing alterations to listed equipment in every case.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
You need to understand you cannot void the listing. The listing applies as the product left the factory. It has nothing to do with what happens to it after it leaves the factory.
You might have a leg to stand on if you took the it's required to be approved route. But then you would have to get the AHJ to have some kind of rule that prohibits what you think you want prohibited.
By the way, I don't believe that what the OP described is a good practice. I'm just not sure that it violates the electrical code in any direct manner.
I'm a little confused because I was mainly agreeing with you.
I think we're into semantics-land a little bit. I understand that the listing itself cannot be voided, but if the listed piece of equipment is altered, you cannot point to that piece of equipment and say it is listed. Agree?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
It was listed when it left the factory. That's the only thing that listing means.
If you take a junction box and cut a hole in it to install a piece of conduit is that box still listed?
The answer is that anytime you combine multiple pieces of listed equipment together it's up to the authority having jurisdiction to approve it. The listing only helps the authority having jurisdiction to determine whether what you are using is generally suitable. It doesn't mean that it's suitable in all cases that someone might choose to use it.
Honest question: doesn't it matter if the alteration (like cutting a hole for conduit) is in accordance with the listing and instructions?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
UL says it is up to the AHJ to decide if a modification to a Listed item makes it 'unsuitable'. UL can provide assistance to the AHJ
Following or going against, manufacturers' instructions should make the AHJ's process easier.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I don't believe that you're going to find a listing instruction for junction boxes for instance, that covers cutting a hole for conduit. In the case of enclosures though there is some general guidance on how you close openings that you might make in the enclosure. But even if you completely ignore that guidance it doesn't change the way it was listed when it left the factory. Once it leaves the factory, it is solely the responsibility of the authority having jurisdiction how it is used. The listing does give the AHJ some pretty good guidance as to what the product might be used for, and even in some cases how it might be used, but it is not a listing issue to modify it once it leaves the factory.
Krusscher
Senior Member
- Location
- Washington State
- Occupation
- Electrician
When I worked at a scrapyard we would build our own machine panels and if we needed a considerable amount of 120v we would throw a xformer on top of the panel and feed a panelboard on the outside of it. I would have him install panelboards on the outside of his panels so him or his employees don't have to go in the panels to reset these.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
we occasionally do something similar if we know that a customer wants some extra circuits.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Some of this comes down to "When does Listing matter?" For the most part, the only time anyone cares about listing is on the initial installation when that installation is done with a permit and inspected. Once it is installed, is anyone going to pull a permit and have an inspection just to add another circuit to a panel? Not likely (unless it is a smaller part of a larger project). So yes, panel listings get "violated" all the time AFTER they are initially installed. It MIGHT matter to an insurance company, but only after the fact in the event of an accident that involves a claim. An insurance investigator might notice an alteration and investigate what the original panel was designed as, then the after-the-fact modification, having violated the original listing, would be grounds for not paying on the claim IF they could prove that was the cause of the loss. There are a lot of IF's in there however.
Back to the issue though; there are likely OTHER NEC related things worth looking into here, such as SCCR listings if the branch circuits that they add are in the Power circuit, or sizing of the Main after adding more branches, or proper adherence to Tap rules, etc. I find that when people do this sort of thing willy-nilly, these are most often the things that get violated.
Breaker panel mfrs make what are called "Mini Power Zones" (which is I think Square D's name for them), which is a potted outdoor transformer and a small load center in a common enclosure. I have, many times, hung one of those off of the back or side of a control panel as a way to provide additional local branch circuits. The primary for that transformer is inside of the panel, but if you need to access the branch breakers, they are on the outside. Solves the SCCR issue and isolates those branch circuits from the control panel power so that if someone plugs in a table saw in the field and it trips the branch breaker, you don't have to turn off the control panel main to open it up and reset it.
Back to the issue though; there are likely OTHER NEC related things worth looking into here, such as SCCR listings if the branch circuits that they add are in the Power circuit, or sizing of the Main after adding more branches, or proper adherence to Tap rules, etc. I find that when people do this sort of thing willy-nilly, these are most often the things that get violated.
Breaker panel mfrs make what are called "Mini Power Zones" (which is I think Square D's name for them), which is a potted outdoor transformer and a small load center in a common enclosure. I have, many times, hung one of those off of the back or side of a control panel as a way to provide additional local branch circuits. The primary for that transformer is inside of the panel, but if you need to access the branch breakers, they are on the outside. Solves the SCCR issue and isolates those branch circuits from the control panel power so that if someone plugs in a table saw in the field and it trips the branch breaker, you don't have to turn off the control panel main to open it up and reset it.
Macbeth
Member
- Location
- Livonia NY
- Occupation
- Automation
Technically:
If the original UL508 shop does not have a procedure describing the installation of additional field components on record with their label, this is 100% a violation of the panel label. This legally requires a field evaluation ($5k) or sent back to the shop in which it was originally created. Even if the panel is field altered by the original holder of the Label it is still a violation. The panel shop is actually the Label, the shop extends its label to the panel. If there is an local AHJ they may issue a variance.
Altering the Panel:
1. It will increase the Panel FLA.
2. It may cause the SCCR rating to be decreased or cause it to be rated if it is not. This would include calculating the feed AFC.
3. The panel design may have never been approved to supply Branch (Power) Circuits, it may have only been a control panel.
4. The panel will not match the schematics on record.
5. Design/Alteration must be done under the supervision of a certified UL MER.
Reality:
UL508 shops avoid appending procedures to their labels most (Shops and UL508 inspectors) don't have any clue on how to create or add a procedure. Custom UL508 panels have a high rate of field modification 99.9% are never field evaluated. with over 2k panels I have only had 2 field evaluation due to panel modifications. I have feild modified panels just last week, doing it this week and plan on doing it next week.
If the original UL508 shop does not have a procedure describing the installation of additional field components on record with their label, this is 100% a violation of the panel label. This legally requires a field evaluation ($5k) or sent back to the shop in which it was originally created. Even if the panel is field altered by the original holder of the Label it is still a violation. The panel shop is actually the Label, the shop extends its label to the panel. If there is an local AHJ they may issue a variance.
Altering the Panel:
1. It will increase the Panel FLA.
2. It may cause the SCCR rating to be decreased or cause it to be rated if it is not. This would include calculating the feed AFC.
3. The panel design may have never been approved to supply Branch (Power) Circuits, it may have only been a control panel.
4. The panel will not match the schematics on record.
5. Design/Alteration must be done under the supervision of a certified UL MER.
Reality:
UL508 shops avoid appending procedures to their labels most (Shops and UL508 inspectors) don't have any clue on how to create or add a procedure. Custom UL508 panels have a high rate of field modification 99.9% are never field evaluated. with over 2k panels I have only had 2 field evaluation due to panel modifications. I have feild modified panels just last week, doing it this week and plan on doing it next week.