USB Wall Sockets - Can I Do it?

[Cinobite]

While we're still going, what is the rough percentage possibility of me electricuting myself if I switch off at the main junction/fuse box? lol I know this seems ambiguous and dependant on a lot of factors.

I have an electrician coming to wire the power into the lights, but I'd light to put the new switch wires in and switch plate on, this involves taking out the current switch cable from the backbox.
(I'd also like to replace a broken back box on a double socket as well)

I'm completely confident in my abilities - it's just screwing in L/N cables (matching in the case of the double switch). It couldn't be easier. I'm also not a moron, I'm sure everyone says that, but really I'm not. I build all my own computers, rewire networks and phone systems and run my own company.
But when I was a kid, I liked to take things apart and subsequently fried myself on the mains, so I'm really anxious about touch an open mains cable.

I know that switching off at the box isolates the circuit (I've done so to check cable direction behind boxes before) and test with something plugged in. But there's always this niggling feeling that I could still get fried. I know it doesn't make sense and I know you electrical types don't give a second thought to opening up a box of wires with something turned on but I'm not even keen on putting in a light bulb lol

So what do you reckon, switch off at the mains and I'm 100%, maybe get a multi meter or one of those contactless pen current detectors?

 

[Cinobite]

.... and tools! I bought a £30 cable detector the other day, says my switch wall has no cables in, says my mains socket cables in the bedroom run up to the loft, I didn't believe it so looked and the cables run down (no detection). Surely something like that shouldn't be legally sold? I used it correctly, it just gave completely false readings. I know that upstairs cabling generally comes straight line up and downstairs straight line down, which is why I didn't trust it and opened the boxes up. But someone who just followed the detector could have drilled straight into a power cable

 

[bernardgreen]

I'm completely confident in my abilities - it's just screwing in L/N cables (matching in the case of the double switch).

Not quite that easy. You missed out the most important connection. the EARTH wire.

 

[Cinobite]

My faceplate and backboxes are all plastic - by all means correct me if I'm wrong - but there's no need to wire an earth anywhere. (apart from the mains sockets I know they have an earth terminal in the plate but the light switches dont)

To be honest, rewiring the switch isn't a big deal if I leave it for someone else, I'm more concerned with making sure the unit is dead so I can run the cable for the extra 2 switches down the wall and into the box ready for the electrician to connect.

 

[bernardgreen]

by all means correct me if I'm wrong - but there's no need to wire an earth anywhere

Where ever you have a cable with Live in it then an earth should be there as well.

Some time in the future you may decisde to have metal faced switches, ther need earthing. A screw though a cable with an Earth is less likely to be come live as there is a chance it will hit the Earth as a well as the Live

 

[Cinobite]

That makes sense, safer - even if not required. In which case, with no earth terminal in the lights (which are double insulated), where would you terminate the earth? (again not something I'll be doing myself)

Another question as you're all so helpful;

So I've installed the spots (mains fed) and wired the 3 of them together in a chain (leaving the mains end for the electrician).
I'm installing 2 sets, a 3 spot on one switch and a 2 spot on another switch. This is in addition to the main light in the room.

Currently I have;

(unconnected) Mains ---------------- light -- light -- light

Would it be worth me getting hold of some kind of "T" junction box to put one on each spot light chain, I would then wire it (dead)

(unconnected) Mains -------------- Light--light--light

|​

Switch​

For each setup, then the electrician would connect each chain to the mains to make it live (if so is there a specific name for that kind of junction box?). Or just leave it and assume there's enough terminals/space to put them straight in where ever he would do that and wire the switch wire however?

The electrician is a family friend (qualified, full time) who said he would help out by connecting the mains but I had to do the bulk of the work. What I don't want is for him to come around and there be parts missing that he needs to make the connection

 

[Cinobite]

Perhaps 2 of these? (one for each set of spots)

http://www.screwfix.com/p/wagobox-light-junction-box/8423f

This makes sense to me, but I wouldn't want to complicate things for him

 

[winston1]

That makes sense, safer - even if not required. In which case, with no earth terminal in the lights (which are double insulated), where would you terminate the earth? (again not something I'll be doing myself)

Another question as you're all so helpful;

So I've installed the spots (mains fed) and wired the 3 of them together in a chain (leaving the mains end for the electrician).
I'm installing 2 sets, a 3 spot on one switch and a 2 spot on another switch. This is in addition to the main light in the room.

Currently I have;

(unconnected) Mains ---------------- light -- light -- light

Would it be worth me getting hold of some kind of "T" junction box to put one on each spot light chain, I would then wire it (dead)

(unconnected) Mains -------------- Light--light--light

|​

Switch​

For each setup, then the electrician would connect each chain to the mains to make it live (if so is there a specific name for that kind of junction box?). Or just leave it and assume there's enough terminals/space to put them straight in where ever he would do that and wire the switch wire however?

The electrician is a family friend (qualified, full time) who said he would help out by connecting the mains but I had to do the bulk of the work. What I don't want is for him to come around and there be parts missing that he needs to make the connection

I'm puzzled. You are leaving the final connection to the mains for an electrician, fair enough, but are prepared to make all these other connections between lights which will eventually become live. A mistake here is just as serious as at the final connection. Surely the electrician should be making all the connections on the chain.