External lights - floods & bulkhead, circuit issues

[wizbongre]

Hi All,
With our current house we inherited what appears to be a very well designed & installed electric system. The previous owners had invested in a full re-wire and whoever actually did it for them did a very neat and tidy job in my (amateur) eyes.

Everything is clearly labelled, circuits are logically switched, fused, structured, etc. If I look at the outlet in the loft for the aerial amplifier I can trace its route back via FCUs to the main CU with its labelling for example.

However... The house has a separate circuit for external lights. This comprises 3 sodium style floodlights bathing the main external areas, 2 bulkhead lights down the side covering bins and side gate; 2 garden lights; a photocell controlling the whole circuit for dusk till dawn operation; 2 relays performing the switching, one in the loft for the floodlights up at eaves height and 1 near the main CU controlling the bulkhead and garden lights. The circuit is fed from a dedicated MCB and then via a couple of FCU’s - one for the whole system and another in the loft switching the photocell circuit.

It has stopped working and I have no idea why!

I think power is fed to the photocell permanently; this then switches the load live via the two relays. I assume the relays are in place as the photocell has a limited load switch rating.

I need to start tracing/testing and could do with some advice where to start/which order to progress. So far I’ve replaced the photocell and the two relays as they were cheap - no change.

We used to be able to hear the downstairs relay click on but it now appears the whole circuit is dead. The MCB and fuses in the applicable 2 FCU’s are working and fine.

Any ideas where to start?!

 

[aptsys]

Any ideas where to start?!

Some pictures of the installation would be useful as a starting point to deduce the likely suspects.

 

[wizbongre]

I knew someone would say that! I’m away for a few days but will grab a load when I’m back home.

 

[Taylortwocities]

You will need a two probe voltage tester. Don’t forget that you’ll need to test that the live and the neutral connections are there.
NOT one of those magic wands and NOT a neon screwdriver. A multimeter is OK for this.

as it is everything that is not working, start at the supply end and work towards the lights. Draw a diagram of the wiring as you progress.

 

[wizbongre]

Yep, guessed I’d be getting my multi-meter out.

Am I right to think I should see permanent power to the photocell and input to the relays, and then obviously switched output from the relays if I chuck a towel over the ‘cell?

Based on memory of the system, the order of tracing would be CU -> FCU -> FCU -> ‘cell -> relays -> lights. I’ll draw it out and grab pictures as I go.

Could a failed sodium floodlight cause issues further back in the supply?

 

[Taylortwocities]

Check the supply is there at the photocell. I would link the cell out (electrically) to eliminate it. The towel method will rely on a the photocell and its wiring bring in place and working, and you may go down a wrong track.

 

[wizbongre]

Good stuff - good point, thanks.

 

[AndyPRK]

Check the 2 fuses are ok with the meter in beep mode.

Don’t mix the fuses up

 

[aptsys]

I'd also be checking you have good neutral connection at the contactors if you are no longer hearing them activate.