Hey hey still a nice thread in 2010....
I work for an old panel building company that is using almost everything that Alaric said at the begining and we are registered for
UL,cUL and CSA to build enclosed customs panels. All of them needs ensure a good products being sold....
If you wanna sell a safe products in Canada you should be CSA and if you sell in USA you need UL like CE for Europe that we actually look for....
It can be seen as a scam at some points because they all ask for the use of components showing their mark to be accepted and at some point they require the same test but each wants to get money for it instead of accepting the test the other certification got....
The needs of the approval is probably the customer choice or it's engeneer but i strongly sugest that customer ask for at least one of them to avoid buying a panel that can be made by someone that know nothing about basic safe rules of panel building....
I sometimes see others panel with the same rules and you have to read the name to find where it is from but sometimes we see some panels that i would class as "I do it myself" that you easily understand it isn't from a good panel building shop....
Yes i know some can be very nice without being approved but you take a risk to buy a panel from them if you don't know very well their job quality.
I can tell for other states or country but where i am, their is also inspection to check if panel get approved.
Even if the rules are strict, it's not so difficult to get the file and follow the rules, you follow a training mostly on panel marking if you already know the electrical code rules. Inspectors comes at the shop sometimes without annoncing (5-10 times a year) just to check if you do it right and you are set! Their is specific files for repeated products but their is also a custom file that permit engeneering of your own panel...
The basic rules is to comform to the code that ask mostly for the following:
Wires size
Spacing
Fusing
Marking
finger safe
tie down everything
and use components that read the right marking: CSA for CSA approval and UL for UL....
We also got this year, a UL xproof file approval but this one require a little bit more time and money...