Connector Compatibility – is cross-mating UL approved?

As a Product Manager here at altE, I get to learn about new products, as well as updates and changes to existing products. Let’s take PV connectors for instance- seems pretty straight-forward, right? PV connectors are safety components which contribute to the operational safety (both personal and functional) of the installation.

A few years ago, when there were shortages on MC4’s – module manufacturers had to make provisions on their connectors, so that they could continue production. Customers were left with the only option of mating with “compatible” connectors. Manufacturers were hearing from their customers that these “compatible” connections were starting to fail. The issue, they found, was that the metallurgical chemistry of the contacts were going to be different unless they were from the same manufacturer. Over time, the difference in chemical composition could cause oxidation that could lead to temperature rise and other problems. Another issue is that, the manufacturers don’t release tolerances for their products, which could result in possible gaps in the contacts when cross mating. **This could lead to arcing, or possibly eventual connector failure – who needs that??

So, what should you do to ensure a UL approved connection?

  1. Ideally, you want to choose modules with the same connector types in a single array.
  2. If, for whatever reason, you need to add or replace a module, and you find you must mix the connector types, the best solution is to use a small Connector Adapter Cable – for example: MC4 to H4, SMK to MC4
  3. In addition, National Electric Code (NEC) now stipulates that when PV modules are installed in readily accessible locations, connectors that click and lock must be utilized. You’ll need a special tool (key) to unlock the connectors.

We just had our 2nd Annual Dealer Conference, and this was a hot topic. Ultimately in talking to the module manufacturers, there is agreement that there needs to be an Industry Standard for the connectors, so customers don’t run into these issues. Even if two brands of connectors were found “compatible” today, either one of the manufacturers could change their specifications without notifying all necessary parties, since there is no standard currently.

But, for now, let’s put an end to the mystery. When connectors of different makes are mated, the safety aspect that they were designed to perform, is not guaranteed. So, no – cross-mating any connector, regardless of the brands involved, is not a UL approved connection. It does not matter that both connectors may have independent UL approvals, as they were tested to their own, specific individual tolerances and specifications. So please, do your part to install a safe and trouble-free system, and be mindful of your connectors!

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Andrea Belford

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1 Comment

  1. Ben

    UL doesn’t certify (or void) intermateability of different brand connectors.

    Think of your desk lamp and wall socket. Thousands of manufacturers of each. UL is not chartered with, nor could they ever accomplish interoperable safety certs between the two. It is impossible and impractical.

    There are thousands of power connectors we use in our lives. They are replete with different brand of components that are safely intermateable without requiring the same brand or a certification. The fuse box in your home has a brand, with different brand of fuses (circuit breakers). Table lamps and wall sockets, light bulbs and receptacles, wire nuts and cables, etc.

    I do agree that there can be a lot of new connector vendors who may have questionable product, but this has nothing to do with whether it’s a power connector is UL certified as interoperable but rather the quality and reliability procedures for the company making them. Make sure you buy from a bankable PV vendor and/or big name connector vendors. “real” PV companies test the heck out of their connectors and do stringent internal testing (way beyond safety cert tests). Same is true for real connector companies. By “real” I mean a company with a balance sheet and brand value that prevents them from intentionally shipping shoddy product. They have too much to lose by taking short cuts that sometimes happen with no-name companies.

    Buying from a PV company that is spiraling into bankruptcy? Caveat Emptor. Otherwise, I would say the connector interoperability discussion is overblown (fueled by MC). As soon as MC loses their leading market share, this question will disappear and we will reach normal operating assumptions as with all power industries.

    Guaranteed.

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