C2 Vs C3 for no RCD on various circuits

[westward10]

The fact it is a rented property is not relevant.

 

[rewireIT]

C2 = danger if single fault occurs (e.g. no RCD outdoors, as cable cut while gardening and contact with Earth likely)

Hey, can you explain to me how the gardening example is different to no RCD protection inside a property? Is it just the contact with the physical earth which is different?

Thinking on that, how can we actually get a belt if we're standing on wood inside our home, since we're not in contact with earth/are only in contact with something that is an insulator?

 

[westward10]

If your body is completely isolated from any means of return then you shouldn't receive a shock. I used to stupidly demonstrate this to apprentices by happily touching live parts.

 

[Flanders]

Hey, can you explain to me how the gardening example is different to no RCD protection inside a property? Is it just the contact with the physical earth which is different?

Thinking on that, how can we actually get a belt if we're standing on wood inside our home, since we're not in contact with earth/are only in contact with something that is an insulator?

Because you are standing directly on the ground which is also possible wet. As you say less likely to get a larger shock standing on your wooden floor in your house. Also your more likely to cut through a cable with the hedge strimmer than a hairdryer

 

[rewireIT]

If your body is completely isolated from any means of return then you shouldn't receive a shock. I used to stupidly demonstrate this to apprentices by happily touching live parts.

What were you standing on when you did this lol? I've seen all the vids of people doing this but even if i knew i was insulated i wouldn't have the balls to do it.

 

[westward10]

I never really took any precautions made a snap decision and did it. Stupid thing to do and did it countless times and experience told me i was kinda 'safe'.

 

[littlespark]

Because you are standing directly on the ground which is also possible wet. As you say less likely to get a larger shock standing on your wooden floor in your house. Also your more likely to cut through a cable with the hedge strimmer than a hairdryer

More likely to drop a hairdryer into a sink full of water though….

 

[rewireIT]

I never really took any precautions made a snap decision and did it. Stupid thing to do and did it countless times and experience told me i was kinda 'safe'.

So was this just standing inside a property?

It's also interesting that people seem to get shocked and killed by appliances in the bath even though they're typically upstairs, in an acrylic tub, which is bolted to wooden flooring, and is part of a building only in contact with the earth via bricks. You'd think you'd be fully insulated.

 

[nicebutdim]

So was this just standing inside a property?

It's also interesting that people seem to get shocked and killed by appliances in the bath even though they're typically upstairs, in an acrylic tub, which is bolted to wooden flooring, and is part of a building only in contact with the earth via bricks. You'd think you'd be fully insulated.

You become part of the circuit and a wet human body has very low resistance, allowing current to flow though it - perhaps even more easily than through the water surrounding you.

 

[nicebutdim]

Best example I can think of is birds sitting on power lines are in contact with live electricity and suffer no ill effects.

If a larger bird makes contact with a second line or something in contact with earth, they get fried as they have now formed a closed circuit.

 

[pc1966]

It's also interesting that people seem to get shocked and killed by appliances in the bath even though they're typically upstairs, in an acrylic tub, which is bolted to wooden flooring, and is part of a building only in contact with the earth via bricks. You'd think you'd be fully insulated.

In a bath you are frequently connected to the Earth via the service pipes. Modern installations with all-plastic pipes might save you as the pure water in the pipes is not very conductive, but given it only takes a little over 30mA to induce heart fibrillation if you are unlucky, you only need under 7k ohm to be killed which can be reached with wet dirty wooden floor boards, etc.

The bathroom is typically the most vulnerable location due to folks being wet in there and many are small so any appliances like heated towel rails, etc are often within arm's reach of the bath/shower, etc. Not to mention the electric showed being in there!

In the 1970s and early 80s (I think) you used to get public information 'adverts' on TV warning about the dangers of electric shock in the garden as most houses lacked RCD protection, but folks were now moving to electric mowers and hedge trimmers instead of doing it by hand. Every year there you could read of a half-dozen or so folks killed by slicing a cable / extension lead and the tool being live and them on the grass, etc.

So there was a campaign to get folks to use RCD adaptors, etc on extension leads or to fit RCD sockets. Over time most houses would be rewired or at least have a CU upgrade so by early 2000s it was becoming less of an issue but you will still find properties lacking RCDs and for specific locations (e.g. outdoors, bathroom) the risk of an accident and/or the vulnerability of the person to the results are much higher than your typical indoor case.

Of course now with battery tools being affordable, convenient and quite powerful there is less need for mains outdoors, but its still a real risk.