Electrical Panel Modification

[Raymond Wand]

What is the definition of a modified electrical panel? Drilling holes, cutting the panel cover, cutting or enlarging holes? Is there any specific regulation against modification?

Any specific code as per the Electrical Safety Code (Canada)?

Thank you.

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[Bill Kriegh]

You're probably going to have to describe what you're concerned about and see what comes up.

Panels, at least the enclosures, are modified frequently. This always starts a war between those who believe any changes to the enclosure create a listing violation and those who understand that you have to change things to use them. For example, we don't know which, if any, knockouts are removed for testing purposes when UL lists a panel. Certainly, they most likely don't test enough panels to go through all the knockout removal combinations. But, to some folks the listing would be violated unless you removed the same one(s), let alone add more holes or enlarge some.

Standard proceedure is to put holes where needed and enlarge existing holes if necessary - in the box. Modification of the cover is generally viewed as pretty much taboo with the exception of removing the tabs so breakers can be installed. Fillers are permitted if a tab is removed in error or a breaker is removed.

Nothing in the NEC specifically prohibits adding or enlarging holes in a panel (or most other boxes)

I'd guess things are pretty much the same north of the border.

[John Kogel]

What is the definition of a modified electrical panel? Drilling holes, cutting the panel cover, cutting or enlarging holes? Is there any specific regulation against modification?

Any specific code as per the Electrical Safety Code (Canada)?

Thank you.

I don't have the code reference, but I have an example of a butchered Canadian panel.
The barrier between the service entry section and the branch circuit section was hack-sawed so Otis could bring the neutral feeder for the shop up to the service connection. As it says on the label, this is not permitted. In Canada, only SEC are permitted in this portion of the panel.