I have an idea for wiring the lights in a room, which I have run past a few electrician friends, and have received contradictory and unsure answers.
There is a large room with two sets of lights - one on each side of the room. Each circuit consists of two 50W 12V halogens. There are currently two switches and two dimmers controlling the circuit.
I like being able to switch on each half of the room individually, but I have realised the dimming levels I want from each side are always the same.
My idea, when I get some other work done, is to put one dimmer upstream of the two switches, so one dimmer controls both circuits.
(i.e. active -> dimmer -> two switches in parallel -> each set of lights -> neutral.)
The sensible advice I have received:
- Check the lights are of a type that can be dimmed. (Yep, they already are being dimmed.)
- Check the rating of the dimmer can handle the extra load. (Yes, with a good safety margin, because they get hot in a wall cavity.)
The conflicting advice I have received:
If one set of lights is on, and you turn on the second set, (a) yes, the original lights will remain the same brightness, and (b) no, the variable resistor will heat up a little, affecting resistance and the brightness will change slightly.
More importantly: leaving a dimmer upstream of the switches, permanently connected to active will (a) be perfectly fine, (b) will be more susceptible to damage due to spikes (e.g. lightning strike) or (c) will make the dimmer burn out more quickly and should be discouraged.
Would have a dimmer attached to active but disconnected from a load cause it to fail more quickly than having it wired normally (i.e. downstream of the light switch.)?