- Reaction score
- 13,475
This is such a common failure in the UK it's got rather boring. It's a combination of barely adequate switch construction resulting in high heat dissipation at the contacts even under good conditions, poorly terminated cables and the stress of forcing the cables back into the box loosening them and displacing the switch contacts. If any contact or termination is not 100% perfect, it will heat enough to oxidise, thermally relax the screw pressure, increase resistance and slide down the slippery slope to this point or worse, by which time it can be hard to point the finger at the switch or the installer.
I think the standard design is daft. The switch should be mounted into the box, then wired in situ, then the cover fitted. That, and a few more pennies spent on the switch spring action and contact design, would prevent most of these.
