# codes regarding control panels



## mburtis (Sep 1, 2018)

This is something that I have been wondering about. When building a control panel can one simply assemble a collection of listed components properly installed ? I am aware of the codes such as UL508A and NFPA79, but say I wanted to build a fairly simple one off field/site built control panel. To run a pump for instance, a drive, a plc, a hmi, maybe some lights, relays, etc. All listed components being used as intended, is that kosher without an assembly listing or a stamped engineering document? This is in reference to an existing plant not a new construction project.


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## splatz (May 23, 2015)

mburtis said:


> This is something that I have been wondering about. When building a control panel can one simply assemble a collection of listed components properly installed ? I am aware of the codes such as UL508A and NFPA79, but say I wanted to build a fairly simple one off field/site built control panel. To run a pump for instance, a drive, a plc, a hmi, maybe some lights, relays, etc. All listed components being used as intended, is that kosher without an assembly listing or a stamped engineering document? This is in reference to an existing plant not a new construction project.


My understanding is that what you're describing is kosher as long as you satisfy the applicable rules in NEC article 409, Industrial Control Panels. All of two pages. Article 409 mentions UL 508A in an FPN but literally just mentions it, doesn't direct you to follow the rules in UL 508A.


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## gpop (May 14, 2018)

If depends if you are a contractor or a employee of the company where the panel will be used.

If a contractor builds a panel technically hes selling a panel.


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## mburtis (Sep 1, 2018)

As this applies to me, I would be an employee of the plant where the panel would be used.


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## paulengr (Oct 8, 2017)

You are drinking the UL Koolaid.

The way UL (really any NRTL) works is that as a manufacturer you make products and submit them to UL for Listing. They do the product testing on samples, look at your design documents, etc. This costs thousands and takes months. But that’s OK if you are making hundreds or thousands of identical parts. The control panel goes through the same process and is Listed under 508.

The problem is that a lot of control panels are essentially one offs. So right from the start the Listing process exceeds the cost and time of the whole panel!

The alternative of course is to build a panel under NEC directly using Listed parts assembled per NEC installation rules. Except that this makes it a shop made part but in most states it’s licensed electrician work. And if your shop is at a state border or has a large customer base you might have to maintain licenses across several states!

So UL cane up with 508A. This allows a panel shop to build control panels as a Listed assembly, no electrician licensing needed, using a “mini NEC” within the standard, using Listed components. Then the whole assembly is stamped under UL 508A without the testing portion because they already tested the individual pieces. UL just inspects and monitors for compliance to their NEC-like (508A) Code.

There are serious limitations in 508A. Everything is built to 60 C wiring for instance. No electrician in their right mind would follow 508A as opposed to NEC. They don’t have to.

As to licensing and such in plants, OSHA says everything must pass an NRTL and it must comply with their “NEC light” that they did back in the 1990s. States individually impose NEC, straight or modified, as state law. Contractors are held to NEC as part of building permits. So the grey area is when owners take on electrical work. Code officials are all about protecting the general public from poor workmanship by licensed contractors. In many states you can apply for permits as an owner but it gets into a tricky legal area having to do with property rights as to how far the state can dictate what you do with your own property. Theoretically it should be Code. Industrial plants must follow Code as per OSHA. So pulling permits for them falls into the grey area. It gets even uglier because most plants if they were honest about it would pull a permit on day one and NEVER get a final inspection. It doesn’t make sense for them. Industrial plants are constantly doing work on their plants. They usually have full time staff of electricians on every shift. They are essentially continuously under construction. Most plants at least theoretically follow NEC at least as an installation standard because at least in theory they should be following it as per OSHA and state law. There is no “public” to protect in most plants inside the fence. It’s more of a safety thing.

This is why licensing for industrial electricians is usually ignored. They aren’t selling services so they aren’t contractors. The employer is acting as the responsible party and hiring and directing people to do work under their supervision. They are also the owner so this is where you get into property rights and whether or not the state can interfere with what the owner is doing. It’s messy and it’s state by state. And for practical reasons many Code officials would rather not deal with it either. Even in central New Jersey, the Code official was being pushed to get more involved. He told me to pull permits on “visible” projects (from the road) and maybe nice easy to inspect “contained” jobs, preferably 240/120 only (no 4160), maybe once every year or two just so he looks like he is doing his job. So we had a great relationship after that. In NJ it’s easier to get along than get lawyers involved and buck the system. In N.C. we never pulled permits except once. Again it was a well meaning corporate idiot. The big hassle was we had to make a plant control room on a second floor ADA accessible. That’s despite the fact that it’s a chemical plant and required every employee to be in physical shape to escape in a few minutes if we had a release of some toxic gas, something impossible to do from a wheel chair. So we had this beautiful super wide, grossly overpriced and overbuilt ramp that went through a bunch of pipe racks and made it really easy to go to the control room without trudging through the mud and water, that will NEVER see any wheel chair traffic.

This gets into the “general duty clause” with OSHA. You can do just about anything electrically as long as it meets OSHA Subchaoter S. As I said, mini NEC and mini NFPA 70E. But if you did that you have to justify your company “standards”...is what you did safe? And also whether or not you met those standards. If you don’t have a standard such as the Ford or GM standard then OSHA will pick one (NEC or 70E) and apply that. This is what got GM in trouble with 70E in 2006....no electrical work standard, only design and installation standards. A plant could choose say CEC (as a US plant) and OSHA couldn’t easily argue otherwise although states could do most plants just use NEC. So moving on then OSHA looks at compliance to that standard. So as an industrial plant you need to adhere to whatever minimum safety standard you choose.

So in a way industrial plants have a sort of “virtual inspection” or you could say they kind of act as the AHJ. They can’t “be” the AHJ but realistically Cide officials even recognize the situation. Most plants haven’t pulled permits in decades. Every time they do it’s always a nightmare for the inspectors and the plants. So most maintain to Code and many to the most current Code without stare exceptions. So if an inspection occurs (OSHA or state) they can demonstrate compliance. Inspectors don’t have a clue anyway. Most content themselves to make sure you put in every screw in a distribution panel. 

So getting back to it, if it’s built on site or by the electrical contractor 508A isn’t needed. If the panel is purchased by either one, 508 or 508A applies. The crazy thing is with modifications. With most Listed assemblies modifications invalidate the Listing. With 508A though it just becomes a site built condition, no longer a Listed assembly but with Listed components. 508 and others don’t work like that because modifications theoretically mean paying about $5k fir a field NRTL inspection to recertify it.


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## B-Nabs (Jun 4, 2014)

In Canada, if you put more than two relays in a box, the building spontaneously combusts. 

Sent from my SM-G975W using Tapatalk


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## just the cowboy (Sep 4, 2013)

I have found it is really up to the plant manager and insurance company.
The plant manager because if something happens and someone gets hurt due to the controls you designed he is the one that is ultimately responsible.

Same with insurance company's.

As an employee I have never had an issue doing upgrades or full system design.
As a contractor I used to do the project work with plant personal most of the time that made it their project in the end.

One of the reasons I shutdown my business was the liability of design. To this day 15 years later I still think " what happens if someone gets hurt on a machine I upgraded" .

Cowboy


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## joe-nwt (Mar 28, 2019)

I'm not a listed panel shop but I build panels from stamped drawings.


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## JRaef (Mar 23, 2009)

In the US, it varies state by state. The NEC _implies _it, but (depending on how you interpret 110.2) stops short of requiring listing. Most states have their own "version" of the NEC, usually by simply "adopting" the NEC, but many of them then add their own requirements by amendment (nobody removes them). A lot of states, especially those in the West, specifically expand on 110.2 to *require *an NRTL listing (NRTL = Nationally Recognized Testing Lab, of which UL is the most well known), using the OSHA list of approved NRTLs as their guide for what can be used. California, Oregon, Washington, Alaska, Hawaii, Nevada, Idaho, Utah, Arizona, New Mexico and Colorado are the ones I know of for sure. I don't know about Wyoming or Montana.


But regardless of that requirement, an often overlooked issue is that, per the *NEC*, if you have any POWER device (CB, starter, drive etc.) you must now have an "SCCR" (Short Circuit Current Rating) on a control panel.
409.110(4):


> Short-circuit current rating of the industrial control
> panel based on one of the following:
> a. Short-circuit current rating of a *listed and labeled
> assembly*
> ...


So in effect, unless it is just a push button station or something, you end up needing an NRTL listing if you are doing a project that is going to be permitted and inspected. 



If you work in a factory and are doing routine maintenance or machinery alterations and there is no permitting or inspection process by an AHJ, then it comes down to _*company policy*_. That then is often dictated by the company insurance policy, many of which will have a "rider" stating words to the effect of "all electrical equipment will be listed and labeled and installed per the NEC", meaning if something goes wrong and they trace it to your unlisted assembly, they are off the hook for paying out for the damages. So a lot of companies will require that all installed equipment is NRTL listed.


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## mburtis (Sep 1, 2018)

Sounds like if I follow NEC and 70E and the company man is good with it than everything should be ok. Especially seeing as the company man is the inspector since I work for the City. Seems like I'm constantly finding myself out in the grey areas.


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## splatz (May 23, 2015)

JRaef said:


> But regardless of that requirement, an often overlooked issue is that, per the *NEC*, if you have any POWER device (CB, starter, drive etc.) you must now have an "SCCR" (Short Circuit Current Rating) on a control panel.
> 
> 
> 
> ...


I thought that "b." above meant that you could use the method in UL 508 supplement SB, but not necessarily that it had to be evaluated / tested / stamped by UL. (If it was UL stamped, a. would apply.) 

I thought that UL 508 supplement SB had two methods, the simple one was to just use the SCCR rating of the lowest rated component, getting the SCCR ratings from a listed component's documentation, or using a default from table SB4.2. 

I can't realistically imagine the panel being inspected and having a discussion with an inspector about UL 508 supplement B but still...


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## varmit (Apr 19, 2009)

Maybe I am naive, but how would assembling a panel out of UL listed components be judged any differently than building and equipment wiring using "UL listed components"of the proper rating? This is something that I have been concerned about, but have yet to discover a definite answer. 

If non listed components are used, that is an entirely different situation. If a machine is installed and the electrical power and controls are not "listed" and the equipment is modified to UL/ NEC standards the a field inspection is usually required.


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## paulengr (Oct 8, 2017)

varmit said:


> Maybe I am naive, but how would assembling a panel out of UL listed components be judged any differently than building and equipment wiring using "UL listed components"of the proper rating? This is something that I have been concerned about, but have yet to discover a definite answer.
> 
> If non listed components are used, that is an entirely different situation. If a machine is installed and the electrical power and controls are not "listed" and the equipment is modified to UL/ NEC standards the a field inspection is usually required.



Two issues.

First one. Panel shops want to sell shop built one off panels with the flexibility of not being licensed electricians to sell across state lines, avoid permit issues, and other reasons. And since many panels are one offs (custom), without full UL 508 inspections ($5000+).

Second. Electricians need an AUC without having to go through the design details of the panel, figure out mounting and proper current ratings, etc. So UL/NEC make SCCR and other ratings mandatory labels. UL 508A has a standard for calculating this.

So 508A lets panelbuilders stay out of NEC and electricians stay out of panel design.


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## MHElectric (Oct 14, 2011)

Wow, I'm out of the loop on the this one! 

What the heck is wrong with building control panels to do whatever you need it to do and using UL listed parts to accomplish this task? 

Isn't that why people hire electricians?


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## mburtis (Sep 1, 2018)

Sounds to me like basically NEC takes precedence over the other standards and the other standards are meant for shops who assemble equipment but aren't licensed electricians? What about NFPA79? How does it relate to everything? Is it a similar deal meant for equipment manufactures who design and manufacture equipment but aren't electricians?


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## paulengr (Oct 8, 2017)

MHElectric said:


> Wow, I'm out of the loop on the this one!
> 
> What the heck is wrong with building control panels to do whatever you need it to do and using UL listed parts to accomplish this task?
> 
> Isn't that why people hire electricians?



If you manufacture say pump skids for a local market only then you could submit everything to say UL (508) for approval. This is fine if you are making say a pump controller or a sensor that will be used on a hundred identical pump skids because you can spread the UL approval process over a hundred pump skids. But if the customer wants something custom, even the smallest change, it has to go through UL all over again. In the sewage lift station business as an example you can order almost anything you want with almost any brand of Scada, combination of starters and VFDs, and so forth. These sell for a couple thousand typically, far less than the cost of UL approval.

So the pump skid company could just hire a licensed electrician. But if you are selling it to someone in another state you need either two licenses or two electricians. It becomes a logistical nightmare for a manufacturer.

So 508A solves the issue. Customers can purchase a fully customizable panel that is UL Listed. The panel shop can build it to 508A requirements and List it without getting into either contractor licensing issues or paying big bucks to have the assembly tested because the components are tested and the shop is inspected to ensure they follow 508A. It’s essentially a licensing program for panel shops where UL becomes the Code officials.


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## paulengr (Oct 8, 2017)

mburtis said:


> Sounds to me like basically NEC takes precedence over the other standards and the other standards are meant for shops who assemble equipment but aren't licensed electricians? What about NFPA79? How does it relate to everything? Is it a similar deal meant for equipment manufactures who design and manufacture equipment but aren't electricians?



Think of it this way. The NRTL (UL, ETL, CSA, FM, etc.) is the third party testing agency that approves equipment for Listing. This should sound familiar...it should sound exactly like what the Code inspectors do. They inspect licensed electrical work to ensure it meets NEC requirements. The Codes are developed using the same process that NFPA uses (consensus standard by a council of experts). The big differences are that the testing labs are private companies, that both the design standards AND the testing procedures are standards, and that generally organizations other than NFPA write the standards. It’s just not their thing...they aren’t manufacturers.

There are tons of consensus standards. For instance NEMA maintains hundreds of standards on all kinds of equipment. They have standards on contactors and overload relays. They are fairly generic (not tied to an NRTL). NEMA MG-1 is used by almost everyone for motors for instance. IEEE writes some too which are mostly known as ANSI standards like the C35 series for switchgear equipment. NRTLs also have captive standards writers. So UL 508A is written by UL.org, a not for profit standards writer. FM also tends to write a lot for fire safety equipment like gas shutoff valves. CSA does a few but mostly they are Canadian specific standards.

All of these standards cover both design requirements and testing standards to verify that equipment meets the design standards. This is a huge difference. UL tests according to the standard. For instance a breaker might only have to survive tripping at maximum rated current (AIC) 3 times. In many sizes that’s all it has to survive. A good quality breaker might survive a lot more than a cheap one but UL only tests to the standard or 3 times. Sometimes it is (rightfully) unsettling for people when they realize that UL stamps are a sign of MINIMUM quality. This is vastly different from NEC that is an installation standard but doesn’t give any direction for inspection. So one Code inspector might actually pull out a Megger and check for ground faults or check wire size calculations and another might only look for missing screws on the doors. So Code inspectors are fairly arbitrary, NRTLs are not.

NRTLs.can theoretically test and approve any product for Listing under any standard that they have the facilities to test. UL.com generally only tests to standards written by UL.org but the others will usually test to ANY standard. So for instance the mining cable standards are maintained by NEMA. That’s not a UL standard so UL won’t test. CSA however will even though they didn’t write the standard.

NFPA 79 is 100% voluntary. It is a standard mostly for automated production lines. It makes it easy for say GM to tell a panel shop what color lights to use, how E-Stoo circuits should be set up, what kind of wiring to use on skid mounted equipment, that sort of thing. Few companies use NFPA 79 exactly as written because they have their own local standards and ideas, or because they don’t fit the mold (design intent). It has no legal binding.

Finally I did not say that manufacturers don’t have electricians. They are just working under a different system (Listing) that is 100% focused on the work product. The system does not care who makes the product or how so long as it complies with standards. If the manufacturer needs the skills if an electrician they should hire one. But you can see where someone that at some point needs to know and understand the Code (NEC) and is subject to inspection all the time might be a little more professional and knowledgeable about what they are doing. If you’ve been in the business at all you probably have seen tons of equipment manufacturer stuff that would never pass Code inspection. And you might even call the manufacturer out on it. The worst offenders are companies like pump skid vendors. They make most of their money on mechanical equipment (pumps, valves, piping, welded assemblies). They get their mechanics to wire it up because electricians are a waste of money and needless extra expense when tradesmen are all the same and mechanics are cheaper. The engineers are mechanical. And we all know that mechanical engineers in particular are the left hand of God. They can do anything. They are superior to all other professions, especially other engineers. Just ask one. They have no problems telling you so.


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## varmit (Apr 19, 2009)

If I am reading between the lines correctly, if the electrician and electrical contractor are both licensed in the same state as the equipment panel is to be used/located, and if UL (or other) listed components were used, and the work was done to NEC and OSHA standards, then would this be considered a compliant assembly?

Another issue for me is the repair and/or upgrade of very old, worn out machines that no "exact replacement" parts exist. In most instances the machines predate any testing or certification by any agency. the manufacturers of these machines have long ago ceased to exist. They also rarely have any sort of documentation, so a person usually must manually trace out wiring. 

It is common for me to find equipment with:

Old three phase starters with only two overloads

Commutator motors, with the jockey motor- a somewhat variable speed motor from the 60s- 70s.

All sorts of obsolete relays and timers.

Panels with no fusing on individual motors or transformers.

VFD brands that no longer exist.

This is a partial list that does not even begin to describe some of the improvised repairs attempted by folks over the years. 

I realize that this is a liability quandary to work on this junk. i always try to fix what I work on correctly, but it is difficult to impossible to be insulated from every possible liability.


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## paulengr (Oct 8, 2017)

varmit said:


> If I am reading between the lines correctly, if the electrician and electrical contractor are both licensed in the same state as the equipment panel is to be used/located, and if UL (or other) listed components were used, and the work was done to NEC and OSHA standards, then would this be considered a compliant assembly?
> 
> Another issue for me is the repair and/or upgrade of very old, worn out machines that no "exact replacement" parts exist. In most instances the machines predate any testing or certification by any agency. the manufacturers of these machines have long ago ceased to exist. They also rarely have any sort of documentation, so a person usually must manually trace out wiring.
> 
> ...



First statement is right there in NEC Article 110. Actually licensing is a separate issue and has nothing to do with the work itself. It has to do with who may perform work on a job within a state for hire.

As to modifying panels, you’ve identified four cases. Its not a Code compliant panel. It’s an “NEC” panel. It’s a 508A panel, or it’s a 508 panel. If it’s an “NEC” panel or not Code compliant, no problem as an electrician. It follows the usual rule where you bring it up to current Code if it’s not replacement in kind. Just like repairing or remodeling any other existing system.

If it’s a 508A panel it all complies with NEC anyway (it’s an NEC sunset) so again, not really a serious issue. Those only started to appear when 508A was written about 15 years ago.

Then we have the most troublesome technically, 508 panels. These are Listed as an assembly. If you modify it there are two options. You can pay to have it recertified by the NRTL. Otherwise you’d have to just replace the whole thing theoretically. But you’d have to find a stamp on it with some way to track down the fact that it’s a 508 panel. Otherwise to maintain compliance you’d have to replace the whole thing or at least the parts not to NEC Code at the time it was built. So a 2 overload relay (pre 1970) would be legal unless you replace it. If anything is say “RU” that’s a bad sign...it’s a component, not an assembly. This is no different than cutting off molded plugs and installing new plugs on appliance cords. It’s modifying a factory assembly, so it’s a no no unless the cord is a Listed one such as SO, not SJO or AWM.

That being said its a very grey area. I have never heard of anyone going this deep if you do Code compliant work. That would be like arguing that you modified a lamp by replacing the plug on it. There is a legal principle here, “de minimus” which translates roughly to don’t sweat the small stuff. We have enough problems with work that is using counterfeit or completely illegal crap from Asia sold on EBay or Amazon or hack work done by all kinds of people. Nothing more scary in old plants than dealing with what the plant maintenance guys leave behind. Why get hung up on someone’s quality workmanship using modern parts to keep old stuff running. If you don’t want the “risk” then bid to replace the whole thing and hopefully your competition won’t just replace the one broken part. It won’t be strictly by the book but it will not be the reason it failed.

As an example on Friday I was in a VFD panel for a sewage plant. It looked like it was a Square D factory panel (508) back in the day, probably 1990s vintage. VFD has been replaced at least twice already. It has an overload relay on the output contactors that is shot (tripping early). It’s obsolete. So replacing it with the newer part is technically a modification but this isn’t swapping a 2 overload relay for a 3 overload relay and adding jumpers because it’s a different brand since the old one doesn’t exist (say Westinghouse). I didn’t look for but there might be some RU relays in it so technically I should replace those, too. As I said...don’t sweat the small stuff.


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## varmit (Apr 19, 2009)

paulengr said:


> First statement is right there in NEC Article 110. Actually licensing is a separate issue and has nothing to do with the work itself. It has to do with who may perform work on a job within a state for hire.
> 
> As to modifying panels, you’ve identified four cases. Its not a Code compliant panel. It’s an “NEC” panel. It’s a 508A panel, or it’s a 508 panel. If it’s an “NEC” panel or not Code compliant, no problem as an electrician. It follows the usual rule where you bring it up to current Code if it’s not replacement in kind. Just like repairing or remodeling any other existing system.
> 
> ...



Yes, these are also my general thoughts on this. If the work that a person does is current code compliant, and an issue ever arises, there is at least some legal defense. Certainly, nothing will prevent someone from being sued, but having some logical basis for the work performed can be the difference in a successful defense and poverty.

I always try to inform customers if something unrelated to the actual problem needs to be fixed. I usually get a reply similar to "It's always worked before, why should I fix it now?'. A person can only do what someone is willing to pay for. The joys of industrial repair for small businesses.


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## JRaef (Mar 23, 2009)

> And since many panels are one offs (custom), without full UL 508 inspections ($5000+).


I think you are confusing UL 508, which is for the COMPONENTS, and UL508*A*, which is for listed panel ASSEMBLY shops; they are separate listings. 

Once you attain a UL508*A* listing of your SHOP AND PROCESS, you don't have UL inspect every single panel, they do 1 or 2 spot inspections per year and review your documentation.


The difference between a UL508A (or ETL508A for that matter) listed shop assembling and listing a panel, vs an electrician assembling a panel from listed components, is that UL508A also inspects and approves your PROCESS of component selection, assembly and wiring methods, testing, documentation and record keeping. That's not to say any individual electrician cannot do it right, UL508A just ENSURES the end user (and an AHJ and the insurance carrier) that someone OTHER than the person who assembled it is making sure it was done right. You may be an honest person with a concioence to make sure corners were not cut in the name of profits, but believe me, that is NOT the case in the wider world. I have seen a lot of ABSOLUTE NIGHTMARES cobbled together in the field using "UL listed parts" that would make your hair curl. My favorite, which the pictures of unfortunately ended up on my ex parthner's hard drive, were of a "control panel" at a rock crushing plant were all of the motor starters were hanging on single nails on a plywood board in a trailer, open wiring to them all using SO cord (and in some cases SJO used on 480V), sprinkler wire and zip cord used for control wiring and push buttons mounted on cardboard boxes. Every component (other than the cardboard boxes) in there was UL listed. It was still a disaster of an installation waiting to kill someone.


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## micromind (Aug 11, 2007)

JRaef said:


> a "control panel" at a rock crushing plant were all of the motor starters were hanging on single nails on a plywood board in a trailer, open wiring to them all using SO cord (and in some cases SJO used on 480V), sprinkler wire and zip cord used for control wiring and push buttons mounted on cardboard boxes. Every component (other than the cardboard boxes) in there was UL listed. It was still a disaster of an installation waiting to kill someone.


Somehow, this doesn't surprise me..........


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## JRaef (Mar 23, 2009)

micromind said:


> Somehow, this doesn't surprise me..........


 Because you must have done work at crushing plants... I will stop short of saying they are ALL cheap, but it is a distinct character trait of the people that own most of them.


"Here, I found this 30 year old soft starter in the bone yard, use it on my new $250k machinery setup...."


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## micromind (Aug 11, 2007)

JRaef said:


> Because you must have done work at crushing plants... I will stop short of saying they are ALL cheap, but it is a distinct character trait of the people that own most of them.
> 
> 
> "Here, I found this 30 year old soft starter in the bone yard, use it on my new $250k machinery setup...."


Sure have!

Also, I agree; not all of them are ridiculously cheap, just the vast majority. 

One in particular stands out.....they wanted me to build a 'field assembled bus duct' out of busbars and insulated standoffs (800 amp) enclosed in some sort of metal duct type stuff and mount breaker enclosures and starters below it. But they weren't entirely chintzy, they wanted A/B 509s for starters. 

These are the most expensive ones but they will take more abuse than anything else. 

I guess there's cheap and sorta smart cheap.......


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