Shocking install

[paulh]

I am currently working on a contract renewing industrial lighting (simple swap out...yeah)and came upon a dodgy situation today.

I was trying to isolate the lighting (lot's of it)and after turning all the mcb's off individually I realised I couldn't turn all the lights off? I then turned them all off and finally darkness!!!!!!!!!!!! The lighting cct feeds are all joined up one way or another thus at least dual feeding the cctsX( which are incidentally on 16amp mcb,s and installed in conduit(imperial)

This installation is at least 30 years old with what looks like no alterations except the odd fitting changed here and there. The original flourescents are all on really old 2 amp 3 pin plugs with soldered connections. I took one of the conduit ceiling roses off and as suspected there is no earth's either. I have been told the building has been inspected?????? obviously by a welder,joiner or plumber certainly not a spark. As you would suspect it was a job stopper. I can't make my mind up if it's wired wrong or there is water/mechanical damage somewhere. my gut feeling is heading towards wiring

It look's like a simple job may make me a millionaire eh.....ho..hum

 

[a1]

Sounds fun, Paul.

 

[Evans Electric]

That job sounds wonderful :_| Is there a back feed to the switched off MCBs , if so , as you say , the feeds are joined together somewhere.

Unless polarity is wrong, live goes out on the blacks and the Mcbs are switching the neutrals. Bit far fetched Eh ! :|

Or is there a contactor somewhere, with the poles strapped across ?

Deke

 

[steptoe]

do you mean NO lights will turn off individually?

could be a crossed contactor (as has been pointed out)

or have you checked for a permanent live(line) for some emergencies that has been reconnected wrong at a replaced fitting somewhere.

as for the earths,

mechanical ?

ie, the conduit is being used as the earth,

remember also, that if the fittings are not accessible under normal use then they need not be earthed - placing out of reach. (this was more acceptable and more widely used a long forgotten time since gone.)

 

[Mr Sworld]

The conduit is being used as the earth. Still 'acceptable' but good practice would mean you run a CPC in nowadays.

 

[paulh]

Hello All sorry for the delay in answering things getting a bit hectic!

Well.....to answer a few queries first

1, there are no contactors on this Install

2, Some not all lights cannot be safely isolated by using a single mcb.

3, This is a good one ...What emergency's there are none on site :^O

4, using the conduit as earth is ok and still very common. Problem being all accesories not having an earth and trying to get one on a corroded(screws gone green) imperial through box ain't a walk in the park.

The job I am doing is part of a national contract to provide energy efficient lighting. This means I should only be changing accessories(loosely)"like for like" although anyone with a brain will realise this isn't possible.

At the moment all I can do is report or if I find anything dangerous Isolate. Somebody is going to have to action all my and my other collegues reports and observation's.

At the end of the day the job is a mess at this particular site(some are very good) and a complete overhaul is not only recommended but I would think mandatory under Hse or the13th/14th/15th/16th and 17th edition;\.

One other thing and probably the most dangerous. As a new socket was required they have simply "tagged" onto any available skt. one socket had at least 5 spurs.....nice

Ah well back tomorrow....fun and games

 

[a1]

one socket had at least 5 spurs.....niceAh well back tomorrow....fun and games

 

[paulh]

Latest episode......... Different db but Another 2 lighting ccts I couldn't Isolate by turning off individual mcbs. live conductors in red with the neutral AND earth(when present) in matching black....containment trunking badly corroded almost to destruction in places.......The remedials on this place are going to cost at least 3 arm's, 6 leg's, and a couple of kidney's (so far)