Earth connections in steel conduit lighting corcuit

[Olivias Grumpy]

Hello
I need to have an existing fuseboard upgraded for insurance reasons.
The property is a 1 bed flat with concrete floors and
Ceilings.
All cabling is done in buried steel conduit.
The ring, cooker and immersion heater circuits are using twin and earth cabling.

The lighting circuit currently has no individual earth wire.
The light positions use a round steel box flush mounted to the ceiling.

Some of the light fittings are steel and glass construction

To improve the circuit is it acceptable to drill and tap the steel conduit boxes to attach an earth tail to it and turn terminate to light fitting? I’ve checked the continuity of the conduit and all positions are good to the existing fuse box.

Alternatively is it ok to use Plastic Light Fittings and switches

Thanks in advance for responding

 

[Murdochcat]

What documentation will you have to provide to said insurance company to say it complies?

 

[SUNRAY]

What documentation will you have to provide to said insurance company to say it complies?

Was the method ever removed by regs?

 

[Harry Bloomfield]

To improve the circuit is it acceptable to drill and tap the steel conduit boxes to attach an earth tail to it and turn terminate to light fitting? I’ve checked the continuity of the conduit and all positions are good to the existing fuse box.

Is the steel conduit threaded steel conduit, or old grip conduit/ are the boxes cast iron, or pressed steel?

 

[Murdochcat]

Was the method ever removed by regs?

I don’t understand this

 

[SUNRAY]

I don’t understand this

Using the metal containment as a CPC was always deemed to be acceptable providing the PFC was adequate.
Is it no longer permitted?

 

[Murdochcat]

Using the metal containment as a CPC was always deemed to be acceptable providing the PFC was adequate.
Is it no longer permitted?

I was only asking what documentation was required by the insurance Co

Still confused

 

[Olivias Grumpy]

Is the steel conduit threaded steel conduit, or old grip conduit/ are the boxes cast iron, or pressed steel?

Conduit is threaded at fuse board positions.
Not sure about ceiling boxes.I’ll need to drop a light fitting to check.

Does it matter about material?

 

[sparkwright]

To improve the circuit is it acceptable to drill and tap the steel conduit boxes to attach an earth tail to it and turn terminate to light fitting? I’ve checked the continuity of the conduit and all positions are good to the existing fuse box.

Alternatively is it ok to use Plastic Light Fittings and switches

Thanks in advance for responding

I think I would be lazy, and use a fly lead wire connected to a crimped ring terminal, and fit the ring terminal between the inside of the ceiling rose or fitting, and the machine screw that goes into the conduit box - IF I can get a sound connection that's not loose.

 

[333rocky333]

If there metric conduit boxes they will already have a 4mm tapped hole in the back of them, on older 2BA besa boxes if not using the two fixing holes, it was quite common to lug a fly lead on to one of them with a screw.

 

[Harry Bloomfield]

Conduit is threaded at fuse board positions.
Not sure about ceiling boxes.I’ll need to drop a light fitting to check.

Does it matter about material?

Yes, the none threaded, old grip conduit, was never intended as being a suitable earth connection, and the grip connections were never cleaned up back to bare metal. It was only intended as mechanical protection.

3/4" threaded conduit lacked an earth terminal in the boxes, so drilling, tapping for a brass screw in the back of the box is a good plan. 20mm metric ones, included a tapped lug in the back of the box.

 

[Olivias Grumpy]

Finally got around to dropping a light fitting
The light was removed to reveal a round conduit box
No earth connection visible inside
The light fitting was attached to the box using the tapped holes.
I think the screws are brass 2BA ?
I rigged up a fly lead attached to the conduit, ran it back to the fuse board. From there I could confirm continuity through the flylead- conduit to the original fuseboard
Then using an Earth Loop impedance meter at the conduit box. Less than 0.5 ohms

Therefore I’m confident I can attach an earth lead to the conduit box and attach to light fittings.
I can attach a suitable earth clamp to the conduit adjacent to the fuseboard and terminate to the earth bar in the new board.

 

[Harry Bloomfield]

The light fitting was attached to the box using the tapped holes.
I think the screws are brass 2BA ?

3/4" conduit then. Be careful with the screws, they can be difficult to source if you mislay them!

 

[333rocky333]

If your having a new fusebox fitted, have you considered getting an earth wire pulled through the conduit

 

[Olivias Grumpy]

Yes I did and discounted the idea very quickly