Switching

[Andy™]

And that’s probably what it is that’s why it should be double pole

no mention of a fan or other. just a simple 2g light switch to operate 2 lights. and again, nothing to suggest it should be double pole

 

[peterspurs]

It’s in a bathroom there will be a fan it’s a new build. They are mostly shared fans. That would most likely be the problem. He said 100 bathrooms if it’s a simple 2 gang switch I bet he wasn’t the first to look at it. I am looking at the bigger picture. Disconnect fan supply simple test then you can eliminate that problem