Metal Clad Sockets

[Drumtochty]

Two things that I have seen but not really noticed until recently!

There is an earth terminal on the back of the socket face of a metal clad socket along with a live and neutral terminal. There is also an earth terminal on the inside of the metal clad socket back box. Should the earth terminal on the rear face of the socket plate and the back box earth terminals be connected to each other with an earth wire?

I have noticed professionally installed metal clad sockets where the wire comes out of the socket back box knock outs with only a rubber grommet in the knock out but the cable is clipped to the wall between the sockets. My issue being that kids could stick things in the space between the grommet and the cable is not physical retained by the socket, in saying that, the cable is retained by the wall clips.

I put in a 20mm stuffing gland into a metal clad backing box and tighten it against the cable coming out of the metal clad socket back box and also clip cable to the wall. between the sockets. Am I being over the top with the stuffing gland.

 

[Badger]

Not at all I also use stuffing glands and I always earth via rear terminal and socket terminal

 

[binky]

There's no real need for a 'flying earth lead ' to backbox, as both lugs are fixed so will earth through the cover screws. Some people fit them, some don't.

 

[Andy™]

There's no real need for a 'flying earth lead ' to backbox, as both lugs are fixed so will earth through the cover screws. Some people fit them, some don't.

unlike metal boxes in a wall, metalclad boxes are exposed and imo should have a cpc to the backbox

 

[Murdoch]

I always connect the cps to the back box

 

[kerching]

Are the stuffing glands you have used suitable/designed for flat twin and earth cables?

Serious question, really!!

put in a 20mm stuffing gland into a metal clad backing box and tighten it against the cable coming out of the metal clad socket back box and also clip cable to the wall. between the sockets. Am I being over the top with the stuffing gland.

 

[Fleeting]

unlike metal boxes in a wall, metalclad boxes are exposed and imo should have a cpc to the backbox

There is no requirement to do this unless you can provide evidence for it.

 

[Fleeting]

I always connect the cps to the back box

For what reason.

 

[Phoenix]

There is no requirement to do this unless you can provide evidence for it.

Its an exposed conductive part, so earthing is necessary

The whole omitting it if one fixed lug and its a recessed knock out box is semi-official guidence from the NICEIC from years ago, it was never meant to apply to a part which was exposed to touch in normal conditions but rather a concealed metal box which could be argued (if your were rather teneuous!) did not fit the definition of an ECP. In the case of lack of evidence, then the default position must be that the exception does not apply and the ecp must be earthed...

 

[Drumtochty]

Are the stuffing glands you have used suitable/designed for flat twin and earth cables?

Serious question, really!!

I have just searched for specific glands for twin and earth and the rubber component in the gland I have used are not shaped for twin and earth cable. They have a circular hole which I assume is optomised for round cable. These multipurpose glands I used are to secure the twin and earth in the metal clad backbox in a safe, dry, indoor area. They do that job well when the the gland nuts are tightened. Also the cable is cliped near the gland with the specific sized twin and earth clips. This is unlike the offshore industry I worked in, where specific glands were used in hazardous areas.

Can I ask you what particular advantage these specialised twin and earth glands would provide in an indoor, dry area when the are used at around 1.8 mts high at the lowest point. I cannot see them being much more secure than the general type plastic glands with soft rubber circular hole type gripping media.

 

[Drumtochty]

The twin and earth glands have in most cases IP66 or IP68 ratings for water ingress. No requirement what so ever in the circumstances these are used in!

 

[Murdoch]

For what reason.

How I was taught many moons ago and I’ve always thought it’s good practice as it’s an exposed part

 

[kerching]

@Drumtochty
I totally agree with you. The NICEIC man had other ideas and got on his high horse when he saw T&E in a gland until I whipped out my box of WINSERTS. ( I only use Wiska glands as they close up to nothing so can be 'used' as a blanking plug)
Then he apologised as he looked up at me on top of my really, reall high horse

 

[binky]

@Drumtochty
I totally agree with you. The NICEIC man had other ideas and got on his high horse when he saw T&E in a gland until I whipped out my box of WINSERTS. ( I only use Wiska glands as they close up to nothing so can be 'used' as a blanking plug)
Then he apologised as he looked up at me on top of my really, reall high horse

I use stuffing glands to keep spiders and woodlice out in garages. Nothing more than that.

 

[BorisJ]

How I was taught many moons ago and I’ve always thought it’s good practice as it’s an exposed part

Not extraneous though. Do you earth your window frames, door handles etc for the same reason?

 

[Drumtochty]

Not extraneous though. Do you earth your window frames, door handles etc for the same reason?

Only if they have an electrical supply to them!!!

 

[Andy™]

Not extraneous though. Do you earth your window frames, door handles etc for the same reason?

exposed and extraneous are completely different

and door handles etc do not meet the definition of extraneous either, nor would window frames