Tired Of Shocks, Diy Wiring

[canuckamuck]

I keep getting shocks when working on my wiring. I always turn of the appropriate switch in the consumer unit and then double check the power is indeed off. But I still get shocks. Not enough to have me flopping on the floor. But enough to have me drop stuff and generate a few expletives. I wear rubber shoes when I do wiring.

I have noticed it is often the neutral that gets me, but other times I don't know what wire gave me a shock.

How do I eliminate this, or do sparkies just get used to it?

[Crossy]

Open the main incomer which should be double pole, this 'should' completely isolate you from the supply.

If you're getting tickles with the incomer open then you have a serious problem that needs professional investigation.

A bitey neutral also needs looking at, possibly an incorrectly configured MEN system.

[canuckamuck]

It is a modern unit with an RCBO, I assumed I could just switch off the zone I am working on and all would be well.

I have heard that some fixtures, such as fluorescent lights can hold a small charge, and that can sometimes zap you a bit.

But I am just trying to get through this house wiring, not much left to go.

Everything works fine and my RCBO doesn't trip when I leave everything alone.

I don't know what a MEN system is

[sirineou]

I don't know what a MEN system is

A Men system is what you use to go Pi Pi

don't you know anything?

[Crossy]

You should just be able to switch off the breaker for the circuit you are working on, IF that's IF the installation is done properly.

The fact that you've been getting bitten by neutrals suggests that you have a house full of 'borrowed neutrals'. These are quite capable of killing you!!

Borrowed neutrals are not normally a serious hazard to the regular user, it's sparkies who get to suffer. Unless you know exactly what you're doing I would just pull the main breaker before working on your electrics.

[canuckamuck]

The neutrals all get wired to the same bar in the unit; 10 screws for ten breakers. I don't see any other way of hooking it up.

But I can see now the logic in shutting off the whole unit, as the neutrals are still part of closed circuits, even though I shut off the live for that zone.

[Crossy]

If you have the same number of black and white wires then you probably don't have any borrows, but it's not guaranteed.

Thai sparks will grab any convenient neutral connection rather than (correctly) running a cable back to the box. It's when you disconnect that neutral that it can become live via the circuit sharing it.

[canuckamuck]

But they are all connected at one end anyways, so how is it different.

BTW I ran the wires myself so there is no borrows, equal amount of black, grey, and greens.

[Crossy]

Sounds good then

A wire that is open at both ends can still bite by capacitive coupling.

[canuckamuck]

Thanks as always Crossy, I really appreciate your help.

[electau]

If you are receiving shocks from any particular circuit when carrying out work on your electrical installation you have not tested before touching.

The main switch or circuit breaker must isolate your main switch board and all circuits originating from it.

It is possible that you have incorrect circuit connections and /or incorrect polarity .

The first is crossed neutrals between circuits, the second is that switching of the neutral instead of the line conductor. Crossed neutrals will affect RCD operation. Crossed neutrals is the term used for "borrowed neutrals".

Both are serious defects and they will not occur if correct testing had been carried out.

You should also check your protective earthing on all final circuits,also the main earth and electrode.

If you have a MEN connection at your main switchboard the main earth conductor will be connected to the neutral bar or link. If your connection is TT ie direct earthing the main earth will be connected to the earth bar or link.

The mandatory tests are. 1. Earthing. 2. Insulation L to E, N to E 3 Polarity testing

4. Correct circuit connectios. 5.Functional testing of all RCD devices by use of the test button.

Polarity testing is L to E 220V, N to E 0V. L to N 220V.

Colour coding of wires are Black - Line, White or Grey neutral, Green or Green/Yellow for earthing conductors.

NEVER work alive. ALWAYS test before you touch. NEVER assume that a wire, busbar or terminal is de-energised until proven to be so.

TT systems may have a slight rise in voltage on the neutral to earth dependant on the distance from the transformer. However if you switch off the main MCB the incoming neutral will be isolated.

[lopburi3]

Are you using an indicating neon screwdriver to check for hot wire? Make very sure that is the wire being switched and not the neutral as you can not trust color codes here and even the main line could have been wired wrong as often neutral is not returned to ground (men). Even when everything is right but there is leakage between hot and neutral (rat bite in attic in my case) you can get bit by neutral (not enough leakage to case breaker to trip and between wires so no ground fault). Rubber shoes might also be a good investment.

[canuckamuck]

If you are receiving shocks from any particular circuit when carrying out work on your electrical installation you have not tested before touching.

The main switch or circuit breaker must isolate your main switch board and all circuits originating from it.

It is possible that you have incorrect circuit connections and /or incorrect polarity .

The first is crossed neutrals between circuits, the second is that switching of the neutral instead of the line conductor. Crossed neutrals will affect RCD operation. Crossed neutrals is the term used for "borrowed neutrals".

Both are serious defects and they will not occur if correct testing had been carried out.

You should also check your protective earthing on all final circuits,also the main earth and electrode.

If you have a MEN connection at your main switchboard the main earth conductor will be connected to the neutral bar or link. If your connection is TT ie direct earthing the main earth will be connected to the earth bar or link.

The mandatory tests are. 1. Earthing. 2. Insulation L to E, N to E 3 Polarity testing

4. Correct circuit connectios. 5.Functional testing of all RCD devices by use of the test button.

Polarity testing is L to E 220V, N to E 0V. L to N 220V.

Colour coding of wires are Black - Line, White or Grey neutral, Green or Green/Yellow for earthing conductors.

NEVER work alive. ALWAYS test before you touch. NEVER assume that a wire, busbar or terminal is de-energised until proven to be so.

TT systems may have a slight rise in voltage on the neutral to earth dependant on the distance from the transformer. However if you switch off the main MCB the incoming neutral will be isolated.

I have to admit that I do not know how to test anything at all, other than turning it on and seeing if it works.

Part of the problem is that I am way out in the sticks. A couple of local electrical guys have seen my work and they just give me a big thumbs up and ask how much the RCBO cost, as they have never bought one.

I do need to start using one of those screwdrivers with the light in them I guess.

I have had trouble getting them to work before too, and decided I couldn't trust them because I tried one on wires I knew to be live and got no response. Maybe there is a technique to it.

I also don't know how to use the test button on the RCBO.

I know all of this makes me sound like an idiot, but I have never done anything like this before. I was going to get local help, but it turned out they just did things jungle style, with no understanding of modern wiring, and no desire to learn anything new.

[marshbags]

I had a problem with isolating the supply at my last house.

I cut it off at the main fuse box and tested a couple of appliances plus a light switch to reassure myself it was isolated.

I began to install and connect my shower unit and finished up with a couple of burns, my plyers and screw driver scarred by heat and lucky to be alive IMHO.

As lopburi has wisely posted I always make sure I have a thick pair of rubber soled shoes on when doing basic maint. work ect and my tools properly insulated, for sure I reckon this is what prevented a more serious scenario.

I found out later that some cowboy electrician had teed into the feed that comes from the outside pole to the property and did so in a place you that was very difficult to see on top of the tin roof of the outhouse, a matter of 4 metres away.

I had to get a proven capable electrician I had used previously and even he found it difficult to spot it.

I finished up installing a new fuse box and having the main supply rerouted to this, prior to entering the property.

A lucky escape, that,s for sure and yet a further lesson regarding DIY in the home and not believing what is normally accepted as safe, especially I,m loathe to say, in Thailand.

The landlord by the way had assured me the power would be isolated at the point of entry and like a fool I took him at his word.

Always check the line is dead with a good quality meter as well IMHO or get a proven qualified electrician to do your work.

Never take things for granted with the electricity supply and the supposed safety cut offs.

marshbags

[lopburi3]

I have had trouble getting them to work before too, and decided I couldn't trust them because I tried one on wires I knew to be live and got no response. Maybe there is a technique to it.

You do know you have to be touching the metal portion on top of screwdriver with bare finger?

[canuckamuck]

I have had trouble getting them to work before too, and decided I couldn't trust them because I tried one on wires I knew to be live and got no response. Maybe there is a technique to it.

You do know you have to be touching the metal portion on top of screwdriver with bare finger?

No, I didn't, I have never watched anybody use one correctly.

So you touch the tip of the screwdriver to the wire you are testing, and then touch the top metal part?

I know I look dumb here, but if you don't know, you don't know. And I am not afraid to ask questions.

[lopburi3]

Yes that is how it works. Try in a wall socket a few times to get the idea of how to use. One socket should light the neon indicator when you touch the metal top end.

[Daffy D]

br />No, I didn't, I have never watched anybody use one correctly.

So you touch the tip of the screwdriver to the wire you are testing, and then touch the top metal part?

I know I look dumb here, but if you don't know, you don't know. And I am not afraid to ask questions.

</p>No such thing as a dumb question, plenty of people here willing to help so don't be shy.As Lopuri said touch the pointy bit of the screwdriver onto the wire and your finger onto the metal bit on the handle. Sometimes in sunlight the neon is difficult to see so double check before handling it.:-)

[transam]

My place they put both the neutrals, in and out to the ''in'' side of the breaker, sooooooo l got whacked and couldn't understand why. I fixed it and no belts. Earthing was another story.

[Tywais]

br />No, I didn't, I have never watched anybody use one correctly.

So you touch the tip of the screwdriver to the wire you are testing, and then touch the top metal part?

I know I look dumb here, but if you don't know, you don't know. And I am not afraid to ask questions.

</p>No such thing as a dumb question, plenty of people here willing to help so don't be shy.As Lopuri said touch the pointy bit of the screwdriver onto the wire and your finger onto the metal bit on the handle. Sometimes in sunlight the neon is difficult to see so double check before handling it.:-)

Also, if your feet are well isolated from the floor via rubber boots or a floor mat it may not light due to no leakage path available for the lamp. Some screwdrivers it is the very top tip and others it's the shirt pocket clamp that needs touched.

[David006]

Sounds good then

A wire that is open at both ends can still bite by capacitive coupling.

more likely inductive unless the insulation is real thin and acting as dielectric..lol

having said that ,was reconnecting my satellite dish last week and got nice belts from the disconnected coax ....from the RF? ....go figure...

Remember on the dew line (distant early warning system) was told stay away from the huge dish as it would fry my naughty bits...

[Crossy]

Sounds good then

A wire that is open at both ends can still bite by capacitive coupling.

more likely inductive unless the insulation is real thin and acting as dielectric..lol

having said that ,was reconnecting my satellite dish last week and got nice belts from the disconnected coax ....from the RF? ....go figure...

Remember on the dew line (distant early warning system) was told stay away from the huge dish as it would fry my naughty bits...

I'm not going to get into a technical discussion here, but it is most definitely a capacitive effect, you may be surprised how much capacitance 20m of twin actually has. The stuff we use in the UK is about 200pF per metre and there's always the possibility of poor insulation adding to the leak.

The tickle you were getting from the satellite co-ax is certainly originating in the receiver which I'm sure was still on the other end. Invariably these have switching power supplies which, despite them being class-2, can leak enough to make the co-ax outer tickle when it's not connected to the grounded dish / LNB (or even when it is connected and the dish isn't a particularly good ground). Yup, mine nibbles too.

[mozzieslapper]

Don't take advice from me as such, but I put a big clunky, common in Thailand over center lever switch just before the circuit box, so I can isolate it all there as well that the mains runs through. I don't trust a made in Thailand master switch inside the box !!

Just an extra layer of safety I guess.

[jombom]

I have had trouble getting them to work before too, and decided I couldn't trust them because I tried one on wires I knew to be live and got no response. Maybe there is a technique to it.

You do know you have to be touching the metal portion on top of screwdriver with bare finger?

No, I didn't, I have never watched anybody use one correctly.

So you touch the tip of the screwdriver to the wire you are testing, and then touch the top metal part?

I know I look dumb here, but if you don't know, you don't know. And I am not afraid to ask questions.

So,you don't know how to use a phase tester, and you are having a go at house wiring.

Amazing Thailand. Just when you think, you have heard it all. What a weird world ??

[canuckamuck]

I have had trouble getting them to work before too, and decided I couldn't trust them because I tried one on wires I knew to be live and got no response. Maybe there is a technique to it.

You do know you have to be touching the metal portion on top of screwdriver with bare finger?

No, I didn't, I have never watched anybody use one correctly.

So you touch the tip of the screwdriver to the wire you are testing, and then touch the top metal part?

I know I look dumb here, but if you don't know, you don't know. And I am not afraid to ask questions.

So,you don't know how to use a phase tester, and you are having a go at house wiring.

Amazing Thailand. Just when you think, you have heard it all. What a weird world ??

I was expecting this post, not that I don't deserve it.

It's a pioneer lifestyle up where I am, and I can't trust a single person to make it safer (the so-called experts are dangerous and refuse to do things the safe way) So I would rather know the electrical system inside out instead of wondering why a family member got hurt.

In my my small brain it seems the best choice. I ask a lot of questions as I go. I have a friend coming up next month that teaches electricians in the west, so he will have a good look at that point.

[jombom]

Good, ask your mate to bring a multimeter and measure the voltages between neutrals and earth (grounds). I suspect you may have up to 40v, which will definitely give you a tickle. There are many reasons -- your mate can explain.

[cigar7]

Just google "RCBO wiring" and you'll get lots of pictures and advice for UK style wiring.

[electau]

The post refered to a normal domestic ( residential type) electrical installation. so inductive or capacitive coupling between conductors may be ruled out. They may occur on very long parrallel cable runs eg in industrial environments.

It is possible that the installation is TT and the neutral has a small voltage relative to earth which is normal. Switch off the main MCB and the see if the minor voltages on the neutral still exist.