RCD"s to existing lighting circuits in a children's nursery

[leebut]

Hi Guys

can anyone help out here, I've just been to look at a lighting fault in a children's nursery which I've now sorted but my question to you guys is:-

the building which was originally a NHS training centre that was renovated and converted 18 months ago by a "reputable builder" into a commercial Children's Nursery, the lighting and power supplies to several rooms have been modified to what extent I am unsure but the lighting circuits were originally micc cables from the early 1960's which the "electrician" has connected PVC to using choc block, the micc has developed live neutral faults and has shorted out.

my initial question is should the Electrician have installed rcd protection to the power and lighting circuits, bearing in mind the micc cables and metal conduit boxes are all 50+ years old, corroded and provide poor earths.

The same electrician wired the permanent live to both the emergency lights and toilet extractor fan using a single insulated brown cable (taken out of T+E cable) to the 32amp ring main circuit laid on top of a metal grid suspended ceiling (the brown cable was as you would expect on a quality installation made up in pieces jointed with choc block)


regards


Lee

 

[Darkwood]

Hi Guys

can anyone help out here, I've just been to look at a lighting fault in a children's nursery which I've now sorted but my question to you guys is:-

the building which was originally a NHS training centre that was renovated and converted 18 months ago by a "reputable builder" into a commercial Children's Nursery, the lighting and power supplies to several rooms have been modified to what extent I am unsure but the lighting circuits were originally micc cables from the early 1960's which the "electrician" has connected PVC to using choc block, the micc has developed live neutral faults and has shorted out.

my initial question is should the Electrician have installed rcd protection to the power and lighting circuits, bearing in mind the micc cables and metal conduit boxes are all 50+ years old, corroded and provide poor earths.

What do the regs say regarding his install methods, any alteration, extension or new circuit should be installed to meet current regulations, so my question is, does it require an RCD?

The same electrician wired the permanent live to both the emergency lights and toilet extractor fan using a single insulated brown cable (taken out of T+E cable) to the 32amp ring main circuit laid on top of a metal grid suspended ceiling (the brown cable was as you would expect on a quality installation made up in pieces jointed with choc block)

Cowboy comes to mind and not to regulations, single insulated should be contained (xcluding earth 4mm+), you cannot run cables across ceiling grid, they should be supported (there are certain cables that can be grid run but these are specialist and expensive and are usually part of a smart fitting system).


regards


Lee

It does sound like a cowboy has been involved especially on your second note.

 

[TJ Anderson]

What were your IR readings after you sorted it out?

 

[davesparks]

50year old micc should not be presenting any major problems, at worst he will have damaged the seal on the pot when mucking about with it and you'll have to reterminate a few ends. It is far more likelu that the faults are in the new additions by the sounds of it.
If corrosion has affected the reliability of an earth connection then an RCD is not the answer, the only answer is to repair the connections.

 

[Deleted member 26818]

MICC is one of the acceptable methods for providing additional protection for cables concealed in walls and if additional protection is required, for cables above ceilings or below floors.
Providing RCD protection is only acceptable for cables concealed in walls providing the cables are run in permitted routes.
However it is not an acceptable method for providing additional protection (if required) for cables above ceilings or below floors.

If the MICC is so deteriorated as to no longer provide ADS, then it should have been replaced.
Whether RCD protection would be required will depend on the type of cable and the installation method used to replace the MICC.

 

[Farmelectrics]

if I was you tell the customer what your finding and request an eicr be carried out

 

[rattlehead85]

Before adding or adapting wiring especially in a building of that nature some inspection and testing should have been carried out especially before disturbing micc cables!! That's half the problem nowadays, few do proper testing either because they are frightened of opening up a can of worms and losing the job or because they have no clue how or what tests to apply to start with!

 

[leebut]

Hello All


thanks for the replies regarding this installation, I removed all the connection to the MICC cables from both the rooms affected plus three other rooms all connected on the same circuit from the lighting distribution board, I've basically rewired the two main rooms with a new 1.5mm PVC cable going direct back to the distribution board and left the other three rooms for the time being with no lighting (as these aren't being used as yet) I've taken photos of all the plastic conduit boxes that have been installed without the covers being fitted also the wiring to the fan and emergency lighting these photos along with a basic report on my findings have been passed to the owners of the Nursery who have forwarded them onto the building contractor who carried out the renovation work 14 months ago.

On Friday afternoon I received a phone call from the Building contractor's "NEW" electrician who's read the report and seen the pictures and has refused to go to the job as its a "Can of Worms" he's told me the building contractor has severed ties with the original electrician, the new electrician had been told to go and fix two lights and a fan, I've copied and pasted my report here

""The initial call out for loss of lighting to the “Snack a Jack” room, found that both the main room and the toilets had been connected to the original MICC (Pyro) cabling in the roof void, the connection had been made using two pieces of “choc block” to the cable tails which had been pulled causing the cable tails to be strained in the original connection resulting in the breakdown in the conductor causing the short between live and neutral conductors, the earth connection to the iron conduit box was in very poor condition so didn’t cause the miniature circuit breaker to trip.


The installation in my view was of very poor quality and was not of safe or good practice and does not comply with “BS 7671:2008 of The Wiring Regulations” with the extent of the work carried out in the renovation to the building at the time of the electrical work being carried out, the electrician who carried out the work should have taken a new supply for the two rooms back to the lighting distribution board in the cleaners store cupboard via the main corridor ceiling void, when he carried out his initial inspection and testing of the existing circuit he would have got poor insulation resistance test results in MICC cable that is possibly over 50 years old.

Other observations found on my inspection of the work carried out in the renovation work was that the wires to the 4 gang grid light switch at the main door into the “Snack a Jack” room were poorly terminated also one of the wires coming out of the emergency lighting test switch was actually 2.5mm T+E cable instead of 1.5mm T+E (see photo), the feed wire from this 4 gang grid switch to the toilet light switch isn’t in “BS 7671:2008 of The Wiring Regulations” prescribed locations again this isn’t good safe practice.


The switched live from the toilet light switch is jointed in an open plastic “through” conduit box which hasn’t had a lid securely fitted (see photo), the next joint on this cable is to a Klik quick connect ceiling rose connector which hasn’t been screwed closed (see photo), the original connection from the MICC (Pyro) cable to the new 1.5mm T+E pvc cable was made in an “open” plastic conduit box which wasn’t fixed to the metal conduit box in the ceiling void also it didn’t have any sort of cable grip to support the pvc cable from damaging the connection to the original MICC connection, again this conduit box was left “open”.


The extractor fan that had been fitted into the ceiling panel hadn’t been connected to the flat ducting rendering the fan useless (see photo) the extractor fan is a timer model with a timed over run facility requiring a permanent live this had been made via a piece of brown single insulated piece of copper wire that is actually short pieces of wire joined together with “choc block” and green/yellow earth insulation tape, the fan should have been installed via a three pole fan isolator switch for “safe isolation” for maintenance, the cable feeding the fan is a excessively large piece of scrap 2.5mm T+E cable that’s has been cable tied up to neaten the mess.


The most dangerous part of the extractor fan and emergency lights wiring is the permanent live supply which is the single insulated (brown) wire that links the two emergency lights to the fan which is laid on top of a metal grid suspended ceiling, where it connects to a length of 2.5mm T+E which is clipped to the exterior wall below the original plasterboard ceiling it passes through the toilet stud wall again clipped to the exterior wall to the outside light fused spur where it is wired into the fused spur’s feed “live” terminal, meaning the single core cable is protected by a 32amp miniature circuit breaker in the power distribution board again in the cleaner store cupboard, three things wrong and dangerous here firstly the cable isn’t isolated on the same circuit breaker as the lighting circuit that its feeding making it impossible to “safely isolate” the lighting circuit, the second danger is the circuit is protected by a 32amp breaker and not a 6 or 10amp breaker that it should be, lastly it is dangerous and against “BS 7671:2008 of The Wiring Regulations” to use single insulated cable without it being in a conduit.


I have also noted that the emergency lighting in the main corridor has been wired using single insulated brown cable and would need further investigation and remedial work carried out, I would recommend that all the emergency lighting in the building is checked and where necessary any poor workmanship be rectified""


Cheers

Lee

 

[Darkwood]

To note here, MICC is well known for its longevity and durability, just because its 50yrs old doesn't mean it needs replacing, normally poor glanding allows moisture in over time so more often than not it can be redressed and brought back to its original electrical sound condition, although experience working with micc is essential.

 

[leebut]

Hi Darkwood

I've checked the terminations and condition of the MICC in some other parts of the building they seem good, it just where this cowboys being having a play it seems to have messed up, there is one other serious problem in the building, the concrete flat roof that had been renovated by another contractor has been leaking in a few areas of the building all above the areas that have been affected by the lighting problems the roofing contractor has also been called back to rectify these issues (the concrete has large drops of water on the underside)


Another point to say again the original electrician left in the ceiling void behind the grid ceiling a 2D light fitting that was still live apart from him removing the switch from the switch wire so the live and neutral loop in/out was still in the fitting all I can say is QUALITY workmanship!!!

 

[Darkwood]

Well sounds like you got you feet under the table there, albiet sorting out someone else's balls ups - goodluck :smile5:

 

[leebut]

The other three rooms that need rewiring I'm putting in a price for that work next week was simpler to deal with the rooms that are being used now and to let the original contractor back to at least rectify their issues that need sorting, but after speaking to the spark on Friday he doesn't want to touch the place and is going to put my name forward for already having worked out the issues having had feet on the ground there for two days