OT: Designing to meet UL Listing Requirements

I am about to begin a project where we will seek UL approval for the machine we are designing and, unfortunately I have no background (yet) for how to get from ground-zero to having an approval-ready design. So here is my question:

Can anyone recommend a method for learning the requirements for developing an electrical design that will cover all the aspects the UL inspectors will be looking for? Are there classes or a handbook I can buy? For those who have done it, how did you get from complete ignorance to become all-knowing?

Any input is appreciated.

Steve[FONT=&quot]
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here are a few things you must do.

#1. get UL508A standards, this is the first thing.
#2. for your application, you must build a duplicate control panel. in fact, you will have to build several duplicate control panels. for ul approval, they will require a duplicate control panel, cad drawings, detailed bom and maybe even more. they require this for destructive testing purposes.

there may be a ul testing shop in your area.

it has been to long since i have worked in a ul listed shop and i cannot remember past this.

hope this helps,
james

It all depends upon what standards you are UL listing to. UL508A refers to the control panels only and is fairly simple.

Do you know what standards apply? Is this for the control panels only or the entire machine?

James - Thanks for the reference to the UL508A Standards. As for the testing shop, I am told there is one nearby and that my people have been in contact with them already. The one concern I had with them was knowing up-front how to be prepared in my design process rather than potentially going through some trial and error method.

mflaugh - we will be seeking listing for the entire machine. It is a very simple machine so, hopefully, it will be relatively easy to do. I do not know what standard apply yet.

Steve

Steve,

Is this a one-off listing? or are you listing the design as well? We have a lot of customers who want our equipment to be listed to a specific standard so we have inspectors come in to our shop to check the equipment.

If it is for listing a design then James is probably correct, you will need to provide them prototypes. And you will probably need to make sure that the design does not change in the future or retesting will be needed.

First suggestion I would make would be to make sure the components of the machine are UL Listed and that you follow the installation procedures exactly.

Mark

Mark,

This will definitely be a design listing so it's good to know we will have to go down the prototype path.

I just went to the UL.com website and see there are over 1000 standards. Any advice on something other than a hard-core standard-by-standard review to identify which ones are applicable? I'm not sure I can stay awake long enough to look at each individually.

As for the installation procedures, I read you loud and clear. Fortunately this should be a relatively easy build so there should be no excuse for not following instructions to the letter.

Steve

Steve,

Honestly, you will probably find it difficult to find a specific standard which will apply to your equipment (unless it has some dangerous function i.e. flying saw).

Most of the standards apply to components and therefore will not apply to your assembled equipment assuming you don't manufacture any of those components. For example, where I work, we manufacture our own stainless enclosures. So, for us, we would need to submit the design for compliance to UL50 if we wanted to. But you will most likely be buying a UL50 enclosure already.

The standards list on the UL website has a search function where you could put a generic term for your type of equipment to check if there is anything specific.

Thanks Mark.

Electrically speaking, nope, no fabrication. Everything will be purchased components going together to form an assembly. What fabrication there is will be on the mechanical side and I'm sure there will be at least a couple of standards that need to be met there.

Well if what you say is correct then hopefully all I will probably have to worry about is proper assembly and I guess let the guys at the testing facility do their thing. Sound about right based on what little I have said?

Steve

Steve,

Sounds about right from what you have said. As long as you follow the NEC, UL should not be a problem. Except for the cost of course!

Make sure you clarify up front if you need to have NFPA 79 apply (Industrial Machinery). That can change a lot of requirements for the control panel and wiring.

Good luck and I hope the design passes on the first inspection!

Mark

Hope that helps!