Sparkies – How to not kill myself?

I’ve got a couple of bits of minor electrics to do at home:

1) replace a few halogen MR16s in the kitchen for LEDs which will involve changing the transformer currently wired in

2) changing a big horrible light fitting in a bedroom to a standard pendant

I’m loathed to call in a professional so intend to diy.

My intention was to just switch off the mains power on the junction box but this will mean I have to go around resetting all the clocks/heating controls afterwards.

If I just flick off the appropriate loops (e.g. Upstairs lights, Kitchen) whats the best way of testing there’s no power in the wires before i start fettling?

I guess I’d like the reassurance of a power meter/tester of some sort. Assuming this is what i need what is a good/solid/reasonably priced one?

Can I have your bikes?

If I just flick off the appropriate loops (e.g. Upstairs lights, Kitchen) whats the best way of testing there’s no power in the wires before i start fettling?

Well, this kind of makes me think you shouldn’t be doing it…

But try turning the light on?

Well, this kind of makes me think you shouldn’t be doing it…
But try turning the light on?

Yes, was going to do that but wondered if a tester would be wise in order to double check.

Can I have your bikes?

sure, but i was thinking of wiring up a dynamo light on my bike to get some practise 😉

But try turning the light on?

It’s entirely possible that poor wiring can leave wires live even if the lights don’t come on. Use a tester, get an electrician, or make sure your life insurance is up to date.

It’s entirely possible that poor wiring can leave wires live even if the lights don’t come on. Use a tester, get an electrician, or make sure your life insurance is up to date.

what sort of tester should i get? there seem to be some cheapo things that look like pens or some more pro looking things with dials on???

So turn the light on before cutting the power.

There is a good chance the RCD will cut power to any circuits it is attached to once you start fumbling around. If you have an RCD.

If I just flick off the appropriate loops (e.g. Upstairs lights, Kitchen) whats the best way of testing there’s no power in the wires before i start fettling?

You never know what is wired into which circuit unless you wired it yourself. Always check with a meter or mains test pen first, although if you’re standing on a wooden chair / fibre glass step ladder, a mains test pen won’t work as you won’t be a good ground.

Personally I always do a final test with the back of a finger (as if its live the recoil is away from the wire), but then I’ve had so many shocks over the years I’m rather blasé about the whole thing….

These only cost a few £, but only work if you’re not isolated from Earth:

how not to kill myself?

Hire a proper sparky, that way you get to stay alive and keep the economy afloat. 😉

The best way to do all this is to wire it all up how you think is correct with all the power off. Then turn the power on and if the RCD trips you’ve got something wrong. Move some of the wires round and try again. When the RCD doesn’t trip and the light works you have it correct. You don’t need to know which colours go in which holes.

That’s how I do it. Sparkies tell you you need an electrician just to protect their jobs. It’s the same reason lawyers use latin to stop us all being able to do our own legal stuff.

I invoke Poe’s Law.

You never know what is wired into which circuit unless you wired it yourself. Always check with a meter or mains test pen first, although if you’re standing on a wooden chair / fibre glass step ladder, a mains test pen won’t work as you won’t be a good ground.

Every day is a school day…, 😯 eek

The best way to do all this is to wire it all up how you think is correct with all the power off. Then turn the power on and if the RCD trips you’ve got something wrong. Move some of the wires round and try again. When the RCD doesn’t trip and the light works you have it correct. You don’t need to know which colours go in which holes.

That’s how I do it. Sparkies tell you you need an electrician just to protect their jobs. It’s the same reason lawyers use latin to stop us all being able to do our own legal stuff.

Troll right ? you know it can be wired up to not trip the RCD and still be wrong right ?

What footflaps said ….

Hire a proper sparky, that way you get to stay alive and keep the economy afloat.

“Proper” is the important word here – the qualified sparky who wired up our house thought telephone cable was the right stuff to use to wire up the mains smoke detectors.

I bought one of those battery powered test pens from Screwfix that flashes a light and beeps when it detects AC.

It seems to work well.

I have only given myself one electric shock and that was when I failed to use the dibber, because I was confident that the light switch I was replacing was on a certain circuit and that was turned off.
It was the switch that turns on the lights on the patio and was in fact wired into the garage circuit, rather than the downstairs lighting circuit; logical now I think about it….I think the realisation that I’d just given myself an electric shock was more of a shock, than the actual shock itself, although my wife said she’d never seen me move so fast (and apparently I let out a girlie scream). 😀

I always take loads of photo’s of the wiring before I enthusiastically unscrew them; particularly when it comes to light fittings! I’m sure there’s more wires in there than strictly necessary just to confuse the keen DIYer….

That’s how I do it. Sparkies tell you you need an electrician just to protect their jobs. It’s the same reason lawyers use latin to stop us all being able to do our own legal stuff.

😉

On a more serious note, I have never understood why people like to have a go at doing the electrics. Do you play with the gas?

I suppose the daisy chaining nature of electrics makes people feel they can do it…until it bites you.

Anyone for a Part P please Bob..

My best electric shock was when I was three, I shoved my finger in a light socket with no bulb in it and burnt the end of my forefinger off (no finger print on that finger now). For this I was given a Penguin biscuit by my mother, since which I have always associated a reward with electric shocks. I blame the parents….

On a more serious note, I have never understood why people like to have a go at doing the electrics. Do you play with the gas?

Yes, yes I do. In fact I spent all morning playing with oxyacetylene, which is a lot more bangy than your boring domestic stuff 😉

Turn it around – why do people not learn and do this stuff themselves? I helped my dad rewire their entire house when I was a kid.

No way in hell I’d use or trust one of those cheap chinese screwdriver things. Don’t even know how the manage to get a CE mark on them.

My first job in spring (ie when I can work with lights off) is to map where the heck all the wiring actually goes (and water/heating pipes at the same time).

Then I can change the lights.

It’s entirely possible that poor wiring can leave wires live even if the lights don’t come on

I have one light, that as far as I can tell is always live. I have honestly never found the switch for it, other than the main breaker. Fortunately, with E24 screw in bulbs rather than bayonet fitting, I can have a bulb left in permanantely that’s just not screwed in all the way.

And one set of GU5.3 popped recently, in the kitchen. I can hear the transformer buzz but there’s nothing coming out. So I actually need to do something now, rather than put it off indefinitely.

footflaps – Member

My best electric shock was when I was three, I shoved my finger in a light socket with no bulb in it and burnt the end of my forefinger off (no finger print on that finger now).

Not quite as good as that, but having licked a few 9v batteries I was keen to see if you could get an electric shock from a scalextric track.
You can. And somewhat unsurprisingly it’s strength is proportional to how much you pull the trigger and it hurts quite a lot!

Sonor – Member

On a more serious note, I have never understood why people like to have a go at doing the electrics. Do you play with the gas?

Depends on what you mean by ‘doing the electrics’….

I wouldn’t think twice about replacing a socket with one of a different type, or a light fitting for that matter. There are no special tools required and it’s just a case (assuming the previous one was wired correctly) of taking the wires out of the old one and placing them in the new one in the same positions.

But, putting new sockets in etc. I would always get an electrician in. The electrician we use has put several new sockets in for us, as well as installing our bathroom extract fan. He’s does a good job and doesn’t charge an extortionate amount, but calling him out just to change a socket face seems a bit unnecessary.

I can’t think of a job involving ‘gas’ that I would consider sufficiently simple to not want to get someone in for.

“Anyone for a Part P please Bob..”

do explain.

240 mains doesnt hurt that much -the act of surprise and the fall from the ladder will hurt more.

go get a 12v car shock and come back to me – that smarts.

go get a 12v car shock and come back to me – that smarts

well i managed to fit a new battery to the car the other day and survived so maybe i’ll be able to pull off the above jobs 😉

stumpy01, be careful with those 9v batteries

The final touch with the back of the hand was something a fireman friend told me about many years ago – if you’re going through a smoke filled building you clear the area in front of you with the back of your hands in case it’s hot or live. Your natural reaction will pull you away from the danger.

Also worth using Tesla’s rule – always keep your left hand in your pocket so any shock goes down the right hand side of your body. I wouldn’t rely on it but it’s extra insurance.

Or do what the guys fixing live tram wires used to do in Moscow when I was there – wear rubber gloves and wellie 🙂

why do people not learn and do this stuff themselves? I helped my dad rewire their entire house when I was a kid.

^^^This! This! Exactly this, yes BRAVO!^^^
Honestly why do people just not know how to do this stuff? I watched my dad blow himself across the bedroom floor chomping into what he thought was the isolated 1st floor ring main. Turns out it was the garage supply that some idiot ex-shipyard* sparky had stapled to the back of the skirting board. I learned some really valuable lessons that day: my dad can jump quite far, test everything & always assume its still powered, some “tradesmen” enter a trade as nobody else will have them, as trail_rat suggests 240v didn’t hurt my dad that much, him recoiling against the marble fireplace did.

I know exactly why we have the wretched part P – because people forgot how, or were too scared to do electrics themselves proficiently, made stupid mistakes & didn’t necessarily do themselves in, but put the next occupier or some unfortunate other sparky in danger. My current house is like this: previously wired by an alarm “engineer”, everything is spurred off everything else, no boxes behind some of the sockets & one socket in the lounge randomly wired into the kitchen ring. The guy clearly had a common sense bypass.

*Victorian house, previously owned by MD of Austin & Pickersgill. Outfitted by shipyards, so electrical cabled nailed to trunking like on a ship, fitted wardrobes from a 1950s ship’s cabin, asbestos-lagged 3″ (yes 76mm) piped central heating clearly nicked from a ship’s engine room, kitchen units with special lips to stop veggies rolling off while at sea etc etc..

240 mains doesnt hurt that much

It does have an occasional side effect of “death” in the right (wrong) circumstances though.

go get a 12v car shock and come back to me – that smarts.

Never mind 12V, the HT circuit can properly focus the mind. I once had a crack off a faulty coil lead, that was something like 35,000V on my Escort (and I think newer cars are a lot higher still).

Also worth using Tesla’s rule – always keep your left hand in your pocket so any shock goes down the right hand side of your body. I wouldn’t rely on it but it’s extra insurance.

erm, aren’t we wired top right to bottom left? So right hand in pocket & test with left?

“240 mains doesnt hurt that much -the act of surprise and the fall from the ladder will hurt more.

go get a 12v car shock and come back to me – that smarts.”

I’m not saying don’t do it, in fact you’re legally ok to do it, but you should then have it checked & signed off by a qualified sparky afterwards. Or at the very least have a good idea & be confident in what you’re doing if you’re going to wing-it.

Part P- http://electrical.theiet.org/building-regulations/part-p/faqs.cfm

240v mains does hurt & people die from it every year, either directly or falling off ladders etc. Then there’s the deaths caused by electrical fires..

This is the sort of thing Part P was introduced to try & prevent-
http://www.telegraph.co.uk/news/uknews/1473919/MPs-daughter-electrocuted-in-botched-fitted-kitchen.html

-Recording a verdict of accidental death, the coroner said: “I am going to record that the death was the consequence of home improvement work.”

footflaps
Always check with a meter or mains test pen first, although if you’re standing on a wooden chair / fibre glass step ladder, a mains test pen won’t work as you won’t be a good ground.

It “may not” work, rather than “won’t work” because your body (and the chair etc) may have enough capacitance to allow AC enough current to flow to light the indicator lamp in the tester!

(and I think newer cars are a lot higher still)

newer cars are coil packs now, so I’d assume that’s LV DC sent thru cables from (and back to) the ECU, and the HT bit comes straight out of the coilpack unit into the sparker(s). spose you could poke a screwdriver inside to find out.

If you dont know what you are looking for how will you know if you have found it ?

On an interesting note along the lines of the MP’s daughter. My old next door neighbour asked me to have a look at her washing machine as she was getting “Slight tingles” off it.
I spent a while trying to find out why there was 240 volts between the tap and the case of the washing machine, which if you would have grabbed both a severe shock would have occurred.
Turns out her husband had recently added a bit of work surface and drilled and plugged the wall for support. The screw had gone straight through the twin and earth of the spur to the socket supplying the washing machine. It had cut the earth wire in two and the screw was touching the socket side of the earth wire and also the phase.
Must happen often ?

It “may not” work, rather than “won’t work” because your body (and the chair etc) may have enough capacitance to allow AC enough current to flow to light the indicator lamp in the tester!

True, however when wearing trainers I can never get one to work so just rely on the back of the finger test, which normally works as you just get a tingle with a good pair of running shoes on your feet.

On a more serious note, I have never understood why people like to have a go at doing the electrics. Do you play with the gas?

I suppose the daisy chaining nature of electrics makes people feel they can do it…until it bites you.

How about the fact that we were all (?) taught about electrical circuits at school? As I recall part of the assessed, practical element of my GCSE physics was wiring a three pin plug. So most people know at least some fundamentals about how electrics should work..

but wiring a 3 pin plug is now pretty much obsolete, and there’s nothing there about how the house is wired up, or supposed to be wired up. and then you unscrew a light rose to find 2x as many wires as you were expecting. and whilst there are conventions about where wires and pipes and batons etc. should go, often they don’t go there

one reason I need to map all of mine – 3 lots of holes for light fittings all put there by previous occupants in a concrete wall, with a wire poking out, none of which are likely to match up with new light fittings, and half of which have been painted over… where can I drill?

all I know is, that some where in there is 230V.

Do you play with the gas?

Yep, do my own gas work as well…

The back of the finger equivalent test for gas is a to run a lighter over a fresh solder joint, if it leaks you get a small flame you can just rub out with a finger and then re-solder (after purging). I believe this is no longer recommended though…..