adding a dimmer switch (in-line)

[bendeneo]

Hello all,

I have an old industrial unit with a good (and well put in) fused switch, that used to control a ceiling fan..... but I have removed the ceiling fan, and attached lighting to it instead.... so the switch is a nice industrial type switch which simply controls the power to the lighting circuit.

What I would like to do is add a dimmer switch, and the way I am envisaging doing it is to put a break in the line between the existing switch and the lights..... probably only about 10 cm away from the switch.

My question..... if I buy a simple dimmer switch from screwfix or similar, how do I best wire it up?

Thanks for any guidance you can give guys.

 

[bernardgreen]

First question.

Can the lamp(s) be dimmed ?

 

[bendeneo]

My feeling is yes, because they are basically standard rose fittings, with 60watt bulbs... I cant be sure, but I would expect they should be.

 

[Taylortwocities]

So standard lamps.

So standard dimmer switch will do it. Count up the number of watts, you dont say how many 60W lamps you have there.
Buy a dimmer at least big enough. Small ones are 250W, but you may need bigger.

Basically at the dimmer location, the neutral and earth wires need to pass straight through (unless you have a metal dimmer that needs earthing).

You need to break into the live wire (power off first!). Power in will go to the terminal on the dimmer that will probably be marked C or COM, power out to the lights comes from either L1 or L2 (it doesn't matter which).

Then you should be all set.

 

[bendeneo]

Perfect, thanks for this.

I am pretty sure it is 6 lights, but now I am wondering if I have got that wrong and it isnt 8!

So if 6 x 60w bulbs then I guess I might be a bit over..... will check the screwfix catalogue for one a bit beefier then.

As I would be turning them down to about half-power at most times (sometimes 75% power), forgive the potentially stupid question, but would this mean a 250w dimmer would survive? I am guess that that would put a load on of 180w? or is that too simplistic?

 

[RF Lighting]

The dimmer rating must match or exceed full un dimmed load.

 

[bendeneo]

Ok, good to know, thanks, I have found one rated 400w on Screwfix, so that should fit the job.

 

[ban-all-sheds]

As I would be turning them down to about half-power at most times

Most times, then, you'll not see much - at half power the lights will be at about 20% of their full brightness.

Even at 75% power they will only be at just over 50%.

If you want 75% brightness you'll be using just under 90% of the full power consumption.