Landing light

[Millymoo]

Hi all, this is driving me mad..help. The landing light in the new old house bulbs were very dull and flickered so I attempted to change the bulbs, the rcd? and trip switch both tripped, tried connecting a single light bulb holder and again when putting in a new bulb the switches trip. Downstairs has a double light switch, downstairs and landing, upstairs has a single switch landing only.as per pics, 1 downstairs 2 upstairs, any ideas?

 

[Lucien Nunes]

From the pics it looks like you have a configuration known as a 'borrowed neutral' where to save cable, the upstairs and downstairs lighting circuits are interconnected to feed the landing light. This was never officially allowed but it did work before the days of RCDs. If a new consumer unit has recently been fitted this might have shown up the issue, which they dodged by fitting a low wattage lamp that didn't pass enough current to trip the RCD. Fitting a larger lamp is causing too much of an imbalance of current passing from one circuit to the other, and tripping the RCD. The usual 'remedy' is to put both circuits on one RCD although this still leaves the circuits in a non-compliant configuration. Perhaps you could post a picture of the consumer unit to clarify?

If you do in fact have a borrowed neutral, some rewiring is usually needed to correct it. However there is a 3-core and earth cable between the two switch positions already. If the cable exiting at the top of the upstairs switch (with only the red and earth connected) also contains a black core, then provided the black is undamaged and can be accessed both at this switch and in the light, then the circuits can be properly separated by changing a few connections. An hour or two of electrician time is probably all that would be needed. If that cable does not have an unused core, then either wireless switching or replacement of that cable might be called for.

 

[Mikegh]

Ya thats the usual scenario

Borrowed neutral and new Rcd board

It will cure it but putting all the house lights on a shared rcd is a poor solution.It creates a lot of hazard

 

[Strima]

It creates a lot of hazard

How does it create a lot of hazard?

 

[Mikegh]

How does it create a lot of hazard?

Think about it

 

[Mikegh]

An appliance fault taking out all the house lights

A single lighting Rcbo would be an improvement on that scenario

 

[Strima]

An appliance fault taking out all the house lights

A single lighting Rcbo would be an improvement on that scenario

Inconvenience yes, but to just state creates a lot of hazard without knowing the installation, layout and number of circuits is just wrong.

 

[brianmoooore]

A bigger hazard is to anyone working on the circuit with the borrowed neutral, all safely locked off, but with other circuits energised. Then someone switches on the landing light.

 

[Mikegh]

Inconvenience yes, but to just state creates a lot of hazard without knowing the installation, layout and number of circuits is just wrong.

Inconvenience or hazardous ?

Matter of opinion

 

[Strima]

Inconvenience or hazardous ?

Matter of opinion

Not a matter of opinion, it would have to be made by assessing the installation and it's use. That can only be done in the property, so to state that it's hazardous without seeing it is incorrect.

 

[Mikegh]

I may be overstating it fair enough