First floor lighting is not working

[Zehroni]

there are 5 light rosses in our 3 bed house on the first floor. all stopped working; i.e. non of the light in the first floor is working. they have their own circuits with RCD protection. I initially thought thought the the beaker id down but it is not. this give me the indication the the wire from the first CU to the fist ross is faulty. one of the 3 core wires must be damage. However, if that is the case should the breaker goes down? any idea why this is happening.?

 

[terryplumb]

Show us a picture of your consumer unit / all of its breakers .
A loose connection could cause failure and not necessarily trip any breakers.

 

[Murdochcat]

Have any changes been recently been made to the upstairs lighting

 

[FrodoOne]

there are 5 light rosses in our 3 bed house on the first floor. all stopped working; i.e. non of the light in the first floor is( sic) working. they have their own circuits with RCD protection. I initially thought thought the the beaker id down but it is not. this give (sic) me the indication the the wire from the first CU to the fist ross is faulty. one of the 3 core wires must be damage. However, if that is the case should the breaker goes down? any idea why this is happening.?

Your diagnoses is likely to be somewhat correct.

Apart from Rodents (or similar) damaging Cables (and the Insulated Conductors within their Sheaths),
it is probable that there is a "loose-connection" (open-circuit) on either the Line or Neutral conductor from/between the CU to the first Ceiling Rose (or Switch).

Any (Miniature) Circuit Breaker (MCB) will not be affected by an Open-Circuit.
A Circuit-Breaker will "trip" only on an Overload.

A RCD (Residual Current Device) will "trip" on an imbalance of current - between the Line and Neutral.
A RCBO (Residual Current Breaker with Overload protection) will "trip" with either an imbalance or an overload.

(Open-Circuit faults on an Earth wire are unlikely to be detected by any "Safety Device".)

 

[Zehroni]

Dear All,
Many thanks for whoever contributed to the post. This is just an update. it was loose connection. The back-room light worked this morning which gave me an indication that the wire from the CU to the first ross is no damage. I went to the loft and traced the wire that is going to the middle bedroom (second ross in the lighting circuits) which is in very good condition and not damage. At this point I turned my attention to the first ross (the back room) where I found the fault loose connections in the middle block. tighten all littles screws and all start working.

 

[securespark]

Any (Miniature) Circuit Breaker (MCB) will not be affected by an Open-Circuit.
A Circuit-Breaker will "trip" only on an Overload.

Or short circuit.

A RCD (Residual Current Device) will "trip" on an imbalance of current - between the Line and Neutral.
A RCBO (Residual Current Breaker with Overload protection) will "trip" with either an imbalance or an overload.

Or short circuit.

 

[EFLImpudence]

... and ... a Residual Current Breaker with Overload protection (RCBO) is a Residual Current Device (RCD).