We have a product, and we're trying to get it MET marked for export from the UK to the US. It uses an APD S10 converter [datasheet] to generate +-250V rails from a 12V supply. It's an isolated converter, but we're not using it as such, we've tied the negative input and the centre output together.
The relevant standard for our product is EN61010. Since the converter is not bridging an isolation barrier, I assumed that the only relevant part would be the flammability requirements. APD can provide us with datasheets showing V0 flamability for the PCB and potting compound, and the whole thing is in a metal case, so that seemed sufficient. And initially the test house agreed.
The test house has now changed their mind. Apparently MET labs think the converter should be tested separately to EN 60950. This seems like a sensible choice of standard, but the converter does not have a UL number and has not been tested. The manufacturer says the norm is to just test it as part of a complete product, in the same way the rest of the circuit is tested. I realise we'd be better off with a UL recognised converter, but there aren't many at the right voltage and it's too late to change - we've already passed EMC tests with this one, and we need to ship ASAP.
What am I missing here? What is the norm? APD is an American company, serving an American market, so there must be some way for them to sell these non-UL-recognised components for inclusion in a UL listed product. But now MET seem to be telling our test house that that is not possible. Yet APD are telling me that it happens all the time. I feel like I'm in the middle of a game of Chinese whispers, and want to understand the American system better.