FCU, spurred to lighting circuit.

Firstly, hello - first post !!
Please let me know if I have done something stupid.
I have wired a unswitched FCU, via a 4 way JB,using the supply from the lighting circuit and a switch from a 2G fitting in the kitchen. I want to use it to connect a LV transformer, to run some cabinet lights.
However, it aint working !! If I remove the switch from the JB and rewire the FCU directly into the circuit, it works, but when I introduce the switch, it doesn\\\'t. If I put a meter across the perm live and SW live I get a strange reading of about 128V, indicating a volt drop somewhere on the switch circuit ?? Why ?? I have checked for continuity and re seated all the connections, but still nothing ?

it is in series with a light somewhere i'll bet. forget taking a supply from the lightswitch - it needs to come from in the ceiling somewhere - ceiling rose usually a good place to start for a permenant supply. remember, there are usually NO NEUTRALS at lightswitches.

Sorry Crafty, I haven't taken a supply from a light switch (that would be stupid !!).

I have cut into the lighting circuit upstairs, under the floorboards and put in a 4 way JB, which is basically wired in the same manner as a rose, with the load being the FCU, but why is it not working via the switch ??

Are you def. taking your L/N feed from the loop?

Have you got 240V across the terms you have tapped off? If so, how have you carried on from there?

When you say the jb is wired like a rose with the FCU as load, does that mean the FCU is connected to a switched live?

securespark said:

Are you def. taking your L/N feed from the loop?

Have you got 240V across the terms you have tapped off? If so, how have you carried on from there?

When you say the jb is wired like a rose with the FCU as load, does that mean the FCU is connected to a switched live?

Click to expand...

I have got 240v across the in/out terminals from the loop, yes.

Yes I have wired it with a SW Live for the FCU, so I can switch on the cabinet lights from the 2G sw, where the main light is switched. i.e one for the main lights and one for the cab lights.

If I remove the switch from the JB and rewire the load across the in/out term, i.e - the loop, it works fine. So I am guessing I have a problem with the switching circuit, which I am 99.9% positive is wired correctly. I havn't got a faulty switch, I have checked !!! The strange thing is the voltage readings across the SW live and perm live, which should read 240v when the switch is off, but I am only getting about half of that ??
and I get nothing at all at the actual switch itself, when it is on ??

My thinking is that I have used a 5A JB and there is a high resistance causing a volt drop across the SW live terminals, is this possible, or am I talking *******s ? It has been known !!!