PE from metal back box to socket

[Paul228]

Have things changed and I missed the memo.
Let's start by saying I'm a fossil. I was trained the old way, were u went with a mate and went to night school and day release. Anyway, was on a domestic fault for a mate of a mate. I rocked up, kitchen ring tripping. Asked any recent works, holes drilled etc, non was the reply ( which was a fib, but no matter). Took both legs out of the board, circuit breaker tests ok, ring has 48k short. Went to split the ring mid point and noticed no earth strap from the box to the socket ( in my day this was mandatory). Found fault, someone had fitted an outside socket, full of water. Anyway back to the internal metal back box. The ring was in a new extension, one year old. So I advised them to get the sparks back to fix it. A few days later, customer rang me and said the sparks said it's not a requirement anymore. My question..since when

 

[Pete999]

Now now Pete you need to go back under the stairs .

Sorry buzz no offence meant.

 

[telectrix]

the option to omit fly leads to back boxes with at least 1 fixed lug came in an amendment to 16th, circa 2004. it's still good practice though.

 

[Toneyz]

Usually, if one of the screw lugs are fixed it is deemed that the metal k.o box is earthed through the 3.5mm screw and eyelet of the socket or other accessories if the designer/installer feels that this mechanical contact is poor or future deterioration is likely then an earth flylead is
required. If both the lugs are adjustable then this is classed as unreliable. There is nothing wrong with going beyond the minimum standard set down by BS7671.

 

[Wilko]

Agreed on both point. But A) why have the termination screw in the box if it's not mandatory ...

Hi Paul - Recently I had to leave a cable joint accessible in a disused metal backbox and so I used it then. .

 

[Paul228]

I'll keep putting them on... belt n braces

 

[robd]

I don't do it on plastic I started in 2006 so guess we were on 16th and no longer a requirement then. I know from doing periodics thinking back the one fixed lug making contact with the brass ring round the screw hole was deemed sufficient, was brought up on site work so wouldn't often do more than required in that situation and old habits die hard whichever side you fall.

 

[MJPD29]

Not required. Back box is earthed by face plate screws. Could be argued you shouldn't be working live hence you shouldnt be opening it without killing power anyway

 

[johnduffell]

It’s niether extraneous or exposed

May sound bizarre on first reading, but the metal backboxes is indeed an exposed conductive part.
This is because it is not insulating and may become live under fault conditions.
The touchable criteria could be indirectly, for example installed into a metal framed wall with a shelf fixed on the other side. Regardless, There is no requirement for any specific standard of insulation to the wall that encloses the back box and the back box is the only thing under the control of the electrical installation.

Having said all that, the screw is deemed enough to earth it!

 

[Pete999]

Agreed on both point. But A) why have the termination screw o the box if it's not mandatory and B) why was I told to do it and have always done it since I was a lad?

Somewhere to hang your cpcs if the wiring is Twin and cpc, on a lighting switch maybe, where there is no earth connection on the switch?

 

[pirate]

Seems just like a nice finishing touch, takes less than a minute, and on surface-mounted metal-clad stuff in a workshop with multiple users of varying skills it makes sense as an extra safety element, imho

 

[Rpa07]

Also helps to use up that roll of 1.5mm green/yellow 6491 that will not ever end.
As with @Murdoch - any upgrades to metal switch faceplates is a must.

 

[Pete999]

Also helps to use up that roll of 1.5mm green/yellow 6491 that will not ever end.
As with @Murdoch - any upgrades to metal switch faceplates is a must.

The termination block is there for when a switch is to be fitted, stops a floating earth

You bin watching Sy Fy movies Mate floating earth WTFs that all about.

 

[JOURNEYMAN]

Appols for my spelling, I have dyslexia, so rely on auto correct.

I knew a dyslexic pimp once who bought a warehouse! ..........sorry, I'll get my coat!

 

[chris gray]

A floating termination is how a none fixed terminated connection is described.

 

[Flanders]

Made me laugh when I came across a earth lead from the earth terminal in a plastic back box to the earth termial in the spur.