A 40-room refurb wired the minibars into the key card circuit and every guest came back from dinner to a warm fridge. Here's exactly what belongs on a key card circuit, what must stay permanently live, and the 800W inductive limit that catches out anyone speccing air conditioning onto the same module.
Two master touch dimmers on the same circuit both power up, and neither works properly. Here's what the master and secondary labels actually mean, how many secondaries one master can support, and why this isn't just a dimmer version of two-way switching.
Two two-way switches can only control a light from two points. A stairwell with three landings needs a third type of switch entirely. Here's what an intermediate switch actually does, where it has to sit in the circuit, and the one wiring mistake that stops the whole run working.
