Changed to plastic back box. Earth wire?

[richie4236]

I recently had to replace a badly installed back box for a light switch. The switch had been moved when the door was 'flipped' to open to the right, not the left, and had been done really badly, with glue, silicon sealant and bits of wood wedging it in place. I decided to do it properly. The switch is right in the middle of the panel, no where near the studs, so replaced the back box with one of the drywall ones which have moving 'ears' that tighten against the aperture as the faceplate is screwed on. All good, and now looks a lot better. Only problem is the absence of a point inside the back box to connect the earth wire, which the original metal back box had. With my very limited understanding of electrics I believe this is there to prevent the box, and therefore the screws, from being accidentally made live? Is that correct? In which case, presumably the plastic back box doesn't need it? At the moment the earth wire is sitting lose behind the switch. Is this okay, or should I have done something with it?

 

[Taylortwocities]

If the switch itself is metal, then the earth conductor must be connected to the earth terminal on the switch.
Otherwise, just terminate the earth wire in a bit of choc block. It can be then left loose in the back box.
I'm assuming the earth wire has a green&yellow sleeve?

 

[ban-all-sheds]

The switch had been moved when the door was 'flipped' to open to the right, not the left

Where does the cable run in the wall, relative to the switch?

 

[richie4236]

I'm assuming the earth wire has a green&yellow sleeve?

Yes. Yellow and green. Was originally connected to the metal back box. The new one is plastic and doesn't have a screw terminal for it. Switch faceplate is plastic. Only exposed metal parts are the screws.

 

[richie4236]

Where does the cable run in the wall, relative to the switch?

As far as I'm aware, straight up into the loft. It's been moved from one side of the doorway to the other. A horizontal distance of about 1m. Forgive my ignorance, but is this an important factor? If it is, I'll go and check the cable run.

 

[Taylortwocities]

Forgive my ignorance, but is this an important factor? If it is, I'll go and check the cable run.

Yes it is. It must be run in a prescribed zone
Read all about it in the WIKI
//www.diynot.com/wiki/Electrics:walls[/QUOTE]

 

[ban-all-sheds]

As TTC said it is important. It is one of those things which is literally (in the proper meaning of the word) of vital, life-and-death, importance. There is at least one documented case of someone dying because buried cables weren't where they should be.

Sometimes when a move such as you describe happens the switch cable is not properly re-routed. If yours does go straight up the wall that's fine.

 

[PBC_1966]

There is at least one documented case of someone dying because buried cables weren't where they should be.

In that documented case, had the cable been put there before or after the whole "safe zone" idea came about? And is it known whether the unfortunate person involved was even aware of "safe zones" for wiring?

 

[ban-all-sheds]

After, I believe, and I don't know.

 

[JohnW2]

There is at least one documented case of someone dying because buried cables weren't where they should be.

Yes, at least partially for that reason. However, more generally, the real problem arises when people who penetrate walls either ignore (or don't even know about) safe zones, or if they foolishly 'assume' that there will not be buried cables outside of safe zones. In the absence of retrospective regulations, it's very possible that there are cables buried outside of safe zones in all but pretty 'new' installations.

In my, albeit limited, experience, one thing one has to be very suspicious/cautious about in an older installation is the 'direct' ('diagonal') route between two nearby accessories which are not vertically or horizontally aligned.

Kind Regards, John

 

[richie4236]

Forgive my ignorance, but is this an important factor? If it is, I'll go and check the cable run.

Yes it is. It must be run in a prescribed zone

Ah. Misunderstood. Couldn't see the relevance of cable routing to the earth wire connection.... but... good point. I'll check the routing. The guy who owned the house before was extremely careless and inept when it comes to DIY. Also an amateur electrician, which seems like a recipe for disaster. We've already found a few worrying things, like a non-functioning strip light that appears to be wired directly into the consumer unit with no obvious switch anywhere(!?), and that one switch in the hallway turns on the interior light and the one outside, while the other switch does nothing. I'm going to have to get someone qualified to come in and check out all the wiring.