Recommended reading to catch up to current requirements for UL listing.
To Tap or Not to Tap
http://www.ul.com/global/documents/...newsletters/electricalconnections/april10.pdf
Here are some highlights:
Panelboards and deadfront switchboards are not Listed to have their busbars tapped unless there are existing holes in the busbars marked with the word “Tap” adjacent to the holes. Other holes in the busbar that are not marked with the word “Tap” are intended for the connection of overcurrent devices, other device’s as identified by the product markings and in the installation instructions or other uses identified by the manufacturer.
When a UL Listed product is modified after it leaves the manufacturing facility, UL has no way to determine if it continues to comply with the applicable safety requirements used initially for its certification without a separate assessment of the modified product.
It is the responsibility of the code authority to first determine whether a modification is acceptable or significant enough to require one of UL’s Field Engineering Services staff members to evaluate the modified product. In determining if a field evaluation should be conducted, the code of Official needs to consider the extent and nature of the modification, and make sure the field evaluation can effectively evaluate the impact the modification has on the product’s ability to comply with safety requirements.
The UL Listing is confirmation that the equipment meets the listing standards when it left the factory. When someone modifies UL Listed equipment in a way that is not approved then UL says it is has no way to determine if it is still meets the Listing standard. That is a long winded way of saying the Listing is no longer valid.
FAQs for Code Authorities
http://www.ul.com/code-authorities/resources/faqs-for-code-authorities/
A UL Listed product was modified in the field. Does this void the Listing?
An authorized use of the UL Mark is the manufacturer’s declaration that the product was manufactured in accordance with all applicable requirements, and was in compliance with those requirements when it was shipped from the factory. When a UL Listed product is modified, retrofitted or altered in any way after it leaves the factory, it is not possible for UL to confirm that the product continues to meet the applicable certification safety requirements unless the field modifications are specifically investigated by UL. It is the responsibility of the Authority Having Jurisdiction to assess the acceptability of the modifications or to determine if the modifications are significant enough to require one of UL’s Field Engineering Services staff to evaluate the modified product. UL can assist the AHJ in making this determination.
Once UL Listed equipment is modified and UL can no longer confirm that it meets the Listing standards it falls back on the AHJ to determine if the equipment is acceptable, just as if unlisted equipment were used in the first place. Once again this is a long winded way of saying, yes the UL listing is voided.
But in PV work much of the equipment we use has to be listed. If a DC combiner is modified outside of the Listing then it no longer meets the Listing standard and it is not in compliance with the NEC to use it, even if the AHJ approves the modification. The AHJ can approve of it's use as an alternative to the NEC requirement as is their prerogative.
AALZ Guide Info
http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073983908&sequence=1
FIELD MODIFICATIONS
The UL Mark applies to the product as it is originally manufactured when shipped from the factory. Authorized use of the UL Mark is the manufacturer's declaration that the product was originally manufactured in accordance with the applicable requirements. UL does not know what the effect of a modification may have on the safety of the product or the continued validity of the UL certification mark unless the field modifications have been specifically investigated by UL. Unless UL investigates a modified product, UL cannot indicate that the product continues to meet UL's safety requirements.
The only exception for a field modification authorized by UL is when the product has specific replacement markings. For example, a switchboard may have specific grounding kits added in the field. The switchboard is marked with a list of specific kit numbers that have been investigated for use in that particular switchboard. Only grounding kits that are included on the product have been investigated for use in that product.
And as always, having done something since you were an electrician in diapers does not mean it is the correct way to do it, it means you have not been called out for it. There is no weaker argument for code interpretation than, "I've done it this way for the last 30 years and never had a problem." It could just mean that no one has caught you that cared to say anything.
