lighting problem

[Rockomuir]

Have been called to a fault where an intermediate switch has not been working properly. However before investigating went to turn the mcb off turning the downstairs mcb off and leaving the upstairs mcb on an all the lights up and down where live. If I swopped the mcb round turning the downstairs on and upstairs offthen downstairs worked okay.

Has any one got suggestions what might be causing this type of fault as just wanted some pointers before starting tracing cable runs and hopefully speed this fault finding up please. The customer said this has like
It for a while so either something has been DIY or it has been like this since they moved in.

I was trained as a new build sparks so I am still
Gaining experience on fault finding older properties.

 

[i=p/u]

id try turning them all off and disconnecting the lights and switches and doing continuity tests to get idea of the circuit, thats cause im slow coach

 

[Marnik]

Borowed Neutral ?

 

[Rockomuir]

I thought maybe a borrowed neutral, when just the mcb breaker is on for upstairs when I operate the hallway lights it turns on upstairs and also turns on the downstairs ones. Web the breaker are both on they become independent switches again

 

[bigspark17]

Hi.. It wouldn't be a borrowed N in this case as turning the mcb off wouldn't isolate the N unless something radically was wrong! there's obviously possibly are a number of reasons for this, but sounds like the upstairs feed has been branched to the downstairs live, and as you said you got called out to a intermediate switch fault I'm assuming this is on a landing/entrance /stairwell... If I was you I'd start in these switches, maybe the owner has put a link in the 2way switch between upstairs live -downstairs live through the 3core.? Just a thought.! Post back when you found out the fault im curious now to know .

 

[Rockomuir]

I agree that it has to be something to do with intermediate. This is strangely wired( to me) it goes form a jb on loft down to the switches, there has got to be a link somewhere

 

[Rockomuir]

having investigated this switch i have found that the intermediate has a feed from the downstairs circuit and there is a link to the upstairs circuit via a junction box. This explains why it was not working. I am in the process of splitting the the supplys and putting it on one circuit. However the customer assures me that this switch has always worked. If that is the case was there ever a time when an intermediate could work with a feed from downstairs and upstairs.

 

[Knobhead]

The customer says it’s worked OK, logic and physics say it couldn’t have.
Logic and physics I can explain, customers, I wouldn’t even attempt to.

 

[tony mc]

They have not had any of the other switches off (2gang) for decoration etc and accidently connected them up the wrong way by swapping the up and down feeds around!

 

[Rockomuir]

Not that I can tell, even though I can fix the problem now, this one has been strange.