Am i confused or is this right?

[Mizunoid]

The guy in the video is saying if we remove bonding from the water pipe, and there's a fault, we will then get a potential on anything that's metal and if we touch the metal object and the water pipe we'll get a belt.

But isn't he at 0 potential anyway and so touching the pipe is irrelevant, he'll still get a belt anyway?

 

[poni]

yes he will get a shock, all metalwork is live because of a fault of 50V to earth and the pipe is at 0V or earth if you like , so the return path is made when he touches any metalwork and the unbonded water pipe.

 

[Mizunoid]

yes he will get a shock, all metalwork is live because of a fault of 50V to earth and the pipe is at 0V or earth if you like , so the return path is made when he touches any metalwork and the unbonded water pipe.

But he's already at 0v because he's stood on the ground, so why would it be necessary for him to touch the pipe before getting a shock?

 

[johnb2713]

The guy in the video is saying if we remove bonding from the water pipe, and there's a fault, we will then get a potential on anything that's metal and if we touch the metal object and the water pipe we'll get a belt.

But isn't he at 0 potential anyway and so touching the pipe is irrelevant, he'll still get a belt anyway?

It depends what he's stood on, he could have some very well insulated rubber soled boots, be stood on wooden flooring etc all which would insulate him enabling his body to be at the same potential as the 'live' metalwork, only when he touches something earthed at the same time would he get a shock.
Have a look at overhead cable guys being lowered onto a live line, 765,000v ..... NO THANKS

 

[Mizunoid]

It depends what he's stood on, he could have some very well insulated rubber soled boots, be stood on wooden flooring etc all which would insulate him enabling his body to be at the same potential as the 'live' metalwork, only when he touches something earthed at the same time would he get a shock.
Have a look at overhead cable guys being lowered onto a live line, 765,000v ..... NO THANKS

There is not a salary big enough for me to do that as a job.

 

[poni]

But he's already at 0v because he's stood on the ground, so why would it be necessary for him to touch the pipe before getting a shock?

at about 2:08min, he is saying if he touched the metal water pipe(when its disconnected from MET) and at the same time any other earthed electrical items (items connected to the MET)he is no longer at 0V if there is an earth fault,

 

[Mizunoid]

at about 2:08min, he is saying if he touched the metal water pipe(when its disconnected from MET) and at the same time any other earthed electrical items (items connected to the MET)he is no longer at 0V if there is an earth fault,

My point is why would he need to touch the water pipe for him to get a shock? He's already on the ground himself so it's not like touching the water pipe is suddenly grounding him.

He's making it sound like you can touch something at 240v potential and be fine as long as you don't touch anything else that's grounded when in fact you're grounded yourself. No?

 

[kerching]

You're not grounded if wearing rubber gloves, insulated foot wear, stood on a rubber mat, fibreglass steps, jump in the air etc

 

[binky]

The whole point of bonding is to keep everything at a touch voltage of 50v or less. If everything is at the same voltage you can't get belted

 

[poni]

My point is why would he need to touch the water pipe for him to get a shock? He's already on the ground himself so it's not like touching the water pipe is suddenly grounding him.

He's making it sound like you can touch something at 240v potential and be fine as long as you don't touch anything else that's grounded when in fact you're grounded yourself. No?

sorry I misunderstood what you were asking,

You're not grounded if wearing a beer gloves, insulated foot wear, stood on a rubber mat, fibreglass steps, jump in the air etc

Like Kerching has posted, you are not always grounded, like on a wooden floor or most types of floor covering, you would need to be in bear feet on soil or any other damp surface,
yes it is ok to at 230V or any other Voltage, as long as you don't make the return path, like Binky posted ,watch the posted video (They at much more than 230V)

The whole point of bonding is to keep everything at a touch voltage of 50v or less. If everything is at the same voltage you can't get belted

 

[johnb2713]

My point is why would he need to touch the water pipe for him to get a shock? He's already on the ground himself so it's not like touching the water pipe is suddenly grounding him.

He isnt really grounded himself, he's most likely wearing shoes with plastic or rubber soles, socks and the shoes are likely to be on floorboards etc. Put a meter from 240v to the floor and measure the voltage.

He's making it sound like you can touch something at 240v potential and be fine as long as you don't touch anything else that's grounded when in fact you're grounded yourself. No?

As above if youre not grounded and you can touch 240v but please dont.

 

[Mizunoid]

He isnt really grounded himself, he's most likely wearing shoes with plastic or rubber soles, socks and the shoes are likely to be on floorboards etc. Put a meter from 240v to the floor and measure the voltage.

Now i'm confused.

I've seen people in the 3rd floor of houses, wearing shoes, standing on floorboards, get a belt off a socket or light fitting. Surely you're not saying that we can simply wear rubber soled shoes and stand on insulated flooring and are now impervious to shocks?

 

[johnb2713]

Now i'm confused.

I've seen people in the 3rd floor of houses, wearing shoes, standing on floorboards, get a belt off a socket or light fitting. Surely you're not saying that we can simply wear rubber soled shoes and stand on insulated flooring and are now impervious to shocks?

If it wa sDC thats exactly what I'm saying, in AC there is capacitive coupling causing some current flow as the AC cycles up and down and yes, you may feel a shock but not a 240v shock. Ask yourself where does the current flow and how? Put a meter probe onto the carpet and into live, what voltage does it see? How is it different for you to be sticking your finger in the socket?
If there's no current flow, there can be no volts drop, if there's no volts drop you have reached the same potential as the live conductor. The problem, being AC there will be some capacitive coupling which will cause a bit of current flow.

 

[Mizunoid]

If it wa sDC thats exactly what I'm saying, in AC there is capacitive coupling causing some current flow as the AC cycles up and down and yes, you may feel a shock but not a 240v shock. Ask yourself where does the current flow and how? Put a meter probe onto the carpet and into live, what voltage does it see? How is it different for you to be sticking your finger in the socket?
If there's no current flow, there can be no volts drop, if there's no volts drop you have reached the same potential as the live conductor. The problem, being AC there will be some capacitive coupling which will cause a bit of current flow.

I do a lot of solar and have had a belt whilst in a loft..

 

[binky]

Now i'm confused.

I've seen people in the 3rd floor of houses, wearing shoes, standing on floorboards, get a belt off a socket or light fitting. Surely you're not saying that we can simply wear rubber soled shoes and stand on insulated flooring and are now impervious to shocks?

But if they had been touching an earth path they could get a proper belt. What bonding is for is protection wherby a fault occurs in say a gas boiler, so the fault can make all the pipework in the house live until the fuse or circuit breaker trips, which can be upto 5 seconds in the case of a fuse. RCDs are to protect people sticking fingers where they don't belong

 

[Geoff1946]

This thread reminds me of two old lines.

1 - Stop and consider how birds can stand on high voltage lines.
2 - If you are at risk of touching a live part keep one hand behind your back. = Good advice in my opinion, as your footwear is likely to limit any shock through your feet, and you can't get 230/ whatever straight across your chest.

 

[roys]

Our work boots had anti-static stamped on the souls which actually meant they did conduct to a certain degree, this was to stop the build up of static charge on us then suddenly discharging when we earthed ourselves which could have caused an ignition of flammable gasses. This meant that when we worked in or on panels that had potentially live accessible parts we had to have insulating rubber mats down.

 

[kerching]

2 - If you are at risk of touching a live part keep one hand behind your back.

I prefer "left hand in pocket"

Just saying


Obviously no use if you are left handed

 

[johnb2713]

I prefer "left hand in pocket"

Just saying


Obviously no use if you are left handed

Hand in pocket is what I was taught incase your arms are thrown around if you get a shock, less likely to contact some earthed metalwork etc.

 

[kerching]

Hand in pocket is what I was taught incase your arms are thrown around if you get a shock, less likely to contact some earthed metalwork etc.

I work on some quite nasty "death inducing stuff, if you get it wrong" someone once said to me "you don't seem to be that interested poking around in there and staring at it for ages, with one hand in your pocket"
He was last seen running to the Phamacy for some Anusol to ease the discomfort of his new defecatory orifice