metal boxes earthing

[John-SJW]

I have seen a few metal back boxes that have no earth terminal lug. Do the regs state the metal back box must have an earth wire to it? The earth on the socket/FCU is earthed to the backbox via the socket faceplate securing screws.

 

[telectrix]

no need to earth the box S LONG AS IT HAS AT LEAST 1 FIXED LUG.

 

[Dustydazzler]

Wind a bit of earth wore round the wall fixing screw

 

[John-SJW]

no need to earth the box S LONG AS IT HAS AT LEAST 1 FIXED LUG.

I never got that. The box had no lug.

 

[telectrix]

then add some od dusty's earth wore. got to be roght.

 

[John-SJW]

then add some od dusty's earth wore. got to be roght.

You are making a suggestion, not addressing what I asked.

 

[Dustydazzler]

the Metal box must be earthed by some method or another

an unearthed metal box is not acceptable

 

[UNG]

I never got that. The box had no lug.

So how are you going to fix the accessory if the box has no lug, replace the box fixes both problems in one go

 

[MJPD29]

What do you mean it had no lug? How do you screw up the faceplate then? Or are you confusing an earthing terminal with a lug? Earthing through the faceplate screws is perfectly acceptable as long as one of the lugs are fixed. No need for a fly lead.

 

[John-SJW]

So how are you going to fix the accessory if the box has no lug, replace the box fixes both problems in one go

It has no earth lug. The terminal

 

[loz2754]

The faceplate fixing screws screw into the back box lugs. One of which must be fixed ie not adjustable.
This is not a regulation, but comes from guidance notes.

 

[littlespark]

Most metal backboxes come with a earth terminal.... never seen one without. Whether its used or not is down to the situation.

A plastic lightswitch, without its own earth terminal needs somewhere to connect the cpc's to... which would be the terminal on the backbox.

Sockets, etc with an earth terminal on them can take the cable cpc's, and the backbox is earthed by screwing back the faceplate, on a fixed lug. The backbox terminal doesnt need to be used.

 

[7029 dave]

Think we have now established the difference between lug and earth terminal.

 

[littlespark]

I’m sure they used to be called earth studs.

when rewiring old country houses, apprentices job to drill the old switch backboxes, tap a thread, and screw on a stud.
Hell to pay if you snapped a drill!

 

[Retroelectric]

There's a new build estate around here where all the switches are 2 plated and the neutral's and earth's are in connector blocks in a metal back box.