PIR failure

[SUNRAY]

HI Guys

I have a query on a lighting circuits which has failed code 1.

The building is a big old terraced house, currently 2 floors of offices and 2 flats on the 2nd floor.

There is a RCBO for lighting, feeding a stairwell and toilets, so it appears on all floors. It has 2 T&E from the CU, one going to the ground floor and basement, the other going to 1st & 2nd. The problem is that one 2 way switching uses the phase from one cable and neutral from the other cable.

The area was rewired and refurbished about 5 years ago. The whole senario is then duplicated for a second stairwell. The other couple of points on the PIR are agreed and resolved.

Opinions please on whether this is a failure as it is not practical to rewire due to the decorative panelling.

 

[LiamPope]

I'm no spark, but can't immediately see the problem myself. If it's all one circuit on the same RCBO then it's not a borrowed neutral, is it? If, say, the circuit was topologically identical, but instead wired in singles, there'd be no talk of a phase and neutral coming from different 'cables' at all. Cant see why it was code 1'd in the first place If I'm dead wrong, I guess it's a good thing I'm no spark

 

[Spark123]

Is any of the wiring in steel conduit or trunking etc?

 

[SUNRAY]

I'm no spark, but can't immediately see the problem myself. If it's all one circuit on the same RCBO then it's not a borrowed neutral, is it? If, say, the circuit was topologically identical, but instead wired in singles, there'd be no talk of a phase and neutral coming from different 'cables' at all. Cant see why it was code 1'd in the first place If I'm dead wrong, I guess it's a good thing I'm no spark

No its not a borrowed neutral and I cant see why its code 1 either.

Is any of the wiring in steel conduit or trunking etc?

Looking at the switch backbox's it seems the cables are buried direct in the plaster and there is no movement. At the CU its in 100x100 trunking but I have no idea where it changes.

 

[SUNRAY]

try a bump

 

[holmslaw]

..

 

[LiamPope]

try a bump

I thought this would get more discussion - folk on here love debating PIR codes . Maybe I was so right there's nothing more to be said . Have you tried to get in touch with whoever did the PIR and find out why this arrangement was code 1'd?

 

[SUNRAY]

try a bump

I thought this would get more discussion - folk on here love debating PIR codes . Maybe I was so right there's nothing more to be said . Have you tried to get in touch with whoever did the PIR and find out why this arrangement was code 1'd?

I must confess I was hoping to get a whole arsenal of ammunition from here and am a little surprised at the lack of thoughts.

Our boss has asked for clarification and the message has come back as 'the hazardous installation is fully described in the report'. The report shows what each cable leaving the DB supplies and it includes a current clamp reading for each cable [not wire] for these 2 circuits [2 cables each] it shows a residual current of about 800mA & 600mA [2x100W & 100+60W].

 

[RF Lighting]

Sounds like another numpty who doesn't know how to do PIRs

I can't be bothered working out what's going on from your description, and wether its right or wrong it doesn't warrant a code 1.

It's not exactly posing an immediate danger to persons property or livestock.

 

[Lectrician]

If both lives are from the same MCB it is NOT a shared neutral.

 

[ColJack]

it sounds like "2 plate" 2-way switching and is perfectly normal and acceptable..
sometimes known as "2 wire" or "the conduit method" ( see WIKI for more info and pictures.. )..

it uses a live from "downstairs", takes 2 strappers from the downstairs switch to the upstairs switch and then a single switched live to the upstairs light which uses the neutral from the upstairs lights.. this isn't a problem where the house only has one lighting circuit as many used to..

 

[SUNRAY]

it sounds like "2 plate" 2-way switching and is perfectly normal and acceptable..
sometimes known as "2 wire" or "the conduit method" ( see WIKI for more info and pictures.. )..

it uses a live from "downstairs", takes 2 strappers from the downstairs switch to the upstairs switch and then a single switched live to the upstairs light which uses the neutral from the upstairs lights.. this isn't a problem where the house only has one lighting circuit as many used to..

Yes spot on, there is a dedicated lighting circuit for the stairwell so there is no chance of it being shared neutral.

It turns out the inspector didn't like the fact that if one of the T&E's were removed from the DB, its neutral could be live via one of the lights on the circuit.
I think there is a very slim comparison there with a ring final.

One of my colleagues resolved it today by taking the 2 T&E's from the RCBO and joining them in a JB [inside the DB] with a short piece of T&E to the RCBO. He tells me it looks lovely

Thanks for the replies.