downstairs lights looking for advice

[scott 123]

hi all
job this morning downstairs /landing lights not working ...lights flickered and went off last night ( trip stayed on)..mcb working (another circuit connected to it works fine) tested this morning (no cpc ) joined line and neutral at board tested at ceiling rose continuity ok .. but no power to any points
any advice what to check for ?

 

[Pete999]

hi all
job this morning downstairs /landing lights not working ...lights flickered and went off last night ( trip stayed on)..mcb working (another circuit connected to it works fine) tested this morning (no cpc ) joined line and neutral at board tested at ceiling rose continuity ok .. but no power to any points
any advice what to check for ?

It will be the same circuit if it's connected to the same OCPD!

 

[DPG]

Not 100% sure on what you are saying here. Do you have continuity on line and neutral from supply to the roses that are not working? Continuity tests will find this problem.
Is it 3 plate, or neutral at switch?

 

[scott 123]

ok .. that light is only a metre away and can follow cable(only feeding that 1 light).....i was trying to say mcb working ....what do you advise i check for next

 

[scott 123]

Not 100% sure on what you are saying here. Do you have continuity on line and neutral from supply to the roses that are not working? Continuity tests will find this problem.
Is it 3 plate, or neutral at switch?

3 plate at rose...continuity on line and neutral at roses that i checked but no power ....surely if continuity ok power should be there

 

[DPG]

You can't have continuity of the line and neutral supply or else the light would be lit!

 

[SparkyChick]

Quick lesson... ohms law... voltage drop is proportional to the current flowing. Under load a high resistance joint may drop enough to prevent the lamps from lighting (depending on the type of lamps).

Depending on what test equipment you are using, it may or may not reveal high resistance joints... depends how much current it uses. So, if you're using a continuity function on a multimeter or AVI, it's not likely to provide reliable results... you should use the low ohms mode of an MFT or suitable stand alone meter as this will use quite a high test current (high test current = bigger voltage drop on small resistances).

 

[SparkyChick]

Should have added, working systematically, work your way along the circuit checking for loose connections (physically and visually) and testing the resistance of each conductor (using a long lead test back to the CU). Pay particular attention to any lights that are not ceiling roses as these are likely to have concealed junctions or choc block attrocities.

 

[scott 123]

You can't have continuity of the line and neutral supply or else the light would be lit!

agreed ...but i have and its not

 

[westward10]

Have you got line continuity at the switched terminal at the rose.

 

[Pete999]

agreed ...but i have and its not

What else is protected by the OCPD controlling the lights that aren't working. Reconnect the leg that you have dissed and as SC says check lights and switches for loose or broken connections.

 

[Spunkywads26]

It may be a stupid answer but have you actually operated the switch when testing.

The way I read it was that you have continuity between loop live and neutral and not switched live and neutral.

 

[Baker1988]

I was going to state what is above aswell. Are you testing at the switch side of the celing rose? Not the loop in the middle? Also have you checked the continuity of the flex drop aswell as there may be a loose wire in the drop its self and are you sure the drop is not damaged. Try changing it.

 

[DPG]

Unlikely to be a switch drop, as all the lights on that circuit have gone out. Time to start again with the continuity tests.

 

[Octopus]

Hum .... interesting.

Linking L & N and using a meter is the best approach, so:

Did you make notes of the readings from different fittings?

Have you tried the same with the neutral not linked at the CU? This may sound odd but you may have a parallel path via another neutral.