FCU no neon display light - what is the safe approach

[mixup]

I have a small issue that I am worried about and need a small bit of advice. Have an FCU (with light) that appears to have blown, the light no longer comes on. Using a Fluke electrical current tester I have established that there is no current....

So is no light a good indication of a blown fuse or worse.

What is the safe way to check, worried that putting power back on may cause an issue.

Any advice?

Thanks

 

[riveralt]

Put the light in another ceiling rose pendant that you know is working and see if the lamp is working.
If it is then is could be the fuse - replace fuse.

 

[mixup]

Sorry, I didn't explain myself well. The FCU powers another circuit, a spur? However the light on the switch no longer comes on when switched on.

http://www.screwfix.com/p/marbo-13a-dp-sw-fcu-neon/79130

Would Neon be the word I was after?

 

[riveralt]

Sorry, I didn't explain myself well. The FCU powers another circuit, a spur? However the light on the switch no longer comes on when switched on.

http://www.screwfix.com/p/marbo-13a-dp-sw-fcu-neon/79130

Would Neon be the word I was after?

I take it that whatever the FCU is connected to doesn't work.
So either the fuse has gone.
or the neon light has gone.
Or a wire has come loose from the FCU
or the FCU has fried.

Start by replacing the fuse.
If that is not the issue disconect the power from the whole of the circuit -not just the spur and have a look behind the FCU to see if any of the cables have come loose.
Alternatively replace FCU - after making sure whole circuit is dead.

 

[sparkwright]

You don't mention if the appliance/circuit that FCU serves actually works!

If there is power on the feed side of the FCU but not on the load side then it would appear the fuse in the FCU has blown.

If there is no power on the feed side or the load side then it would appear a fuse/mcb/rcd has blown at the consumer unit.

Neons can blow, and still allow the FCU to otherwise function.

 

[mixup]

Thanks all, will test tomorrow. Fingers crossed!

 

[mixup]

I have taken out the FCU (spur) can see that its wired up but the Fluke tester is giving me no responses when the power went back on, perhaps as the switch is off/and fuse is missing.

Looking at the wiring I can see that there is wiring into the Spur, three cables in fact, one going to an outside point.

So does this sound like a fuse issue?

 

[JohnD]

changing the cartridge fuse in the FCU is the quickest and easiest thing to do. Have you done that yet?

if the FCU feeds a faulty appliance then the new cartridge fuse may immediately blow, so test the cartridge fuse before you put it in, and after you take it out (if the fault remains)

neons more often get slowly dimmer rather than suddenly "blowing"

You haven't said where you are putting your tester, and you haven't said what the FCU feeds, and whether it works or not.

 

[wingcoax]

Use your fluke on the incoming terminals of the FCU. This will tell you if the main supply is ok or not. If power to FCU then the cartridge fuse in fcu is suspect.

 

[Taylortwocities]

Only use a fuse of the same current rating as the old one, if you are replacing the fuse!

 

[EFLImpudence]

mixup - we don't seem to be getting very far.

It would be useful (essential) if you answered the questions you have been asked.

Here's another one.

In the original post you said you had tested for 'current'.
Did you actually mean 'current'; if so, how did you do this?

 

[mixup]

Using the Fluke elsewhere on FCU's and switches I get a positive indication of power.

However I have tested the fluke over the back of the FCU and its wiring and I get nothing.

13a fuse added and still nothing.

Suspecting a wiring issue upstream.

New house for my sister in law so have no idea the history.

 

[JohnD]

Using the Fluke elsewhere on FCU's and switches I get a positive indication of power.

I have a feeling you are not using a meter with probes that tells you what the voltage is.

And why won't you answer our questions?

 

[Taylortwocities]

However I have tested the fluke over the back of the FCU and its wiring and I get nothing.

This Fluke thing sounds like a volt stick and will not help you in this situation.

You need a proper two probe voltage test instrument or a multimeter.

When you have got one of those then start testing again. Following the advice given above.

 

[mixup]

Aha Thanks very much, will get one and test.