knockouts in boxes

[gunar115]

We give the electricians meter sockets for them to install at our customers. They want to create their own knockouts because the provided ones in the sockets do not always fit their application. We have been told by the socket mfgrs that this ruins the UL listing. Has anyone ran into this?? We would like to allow them to add knockouts as long as none of the new ones are physically closer to the electrical connections. Input welcome, thank you.

 

[iwire]

Here is what UL says about it.

Field Modifications
What happens to the Listing if a UL-Listed product is modified in the field?
An authorized use of the UL Mark is the manufacturer?s declaration that the product was originally
manufactured in accordance with the applicable requirements when it was shipped from the factory. When
a UL-Listed product is modified after it leaves the factory, UL has no way to determine if the product
continues to comply with the safety requirements used to certify the product without investigating the
modified product. UL can neither indicate that such modifications ??void?? the UL Mark, nor that the
product continues to meet UL?s safety requirements, unless the field modifications have been specifically
investigated by UL. It is the responsibility of the Authority Having Jurisdiction (AHJ) to determine the
acceptability of the modification or if the modifications are significant enough to require one of UL?s Field
Engineering Services staff members to evaluate the modified product. UL can assist the AHJ in making this
determination.

 

[augie47]

Interesting, Bob. First informed answer I've seen to that age-old question. Thanks