Thoughts on Removing Electric Fire with 2 fuse points

[ban-all-sheds]

Ah perhaps we're getting crossed wires, no pun intended, I'm guessing you are referring to the whole system, that it has an earth path, whereas I'm referring and what I'm reading, is referring to end points and items that are double insulated etc which don't have a requirement to be earthed themselves. You wouldn't, for example, earth a plastic back box or some lights that are double insulated

Ah - sorry - I thought this:

I couldn't see an earth to the back box

meant that there wasn't one there.

 

[Cinobite]

No worries

 

[PBC_1966]

Absolutely, which is why I have always ran a flylead to the box - better safe than sorry right!

Reardless of whether it's generally considered acceptable not to in some cases, I certainly always do so. It's just a few inches of wire (which is generally acquired from the cable off-cuts anyway) and a few seconds extra work to include it.

 

[Cinobite]

^^ Agreed.

As we're on the subject of earthing, I wonder if you could tell me, is there a regulation etc that states anything metal inside a cavity must be earthed?
While it's not an electrical issue, I'm hoping to embed 2 painted metal uprights of "twin slot" shelving into the actually wall behind the plaster (following this project: https://www.avforums.com/threads/how-too-diy-floating-shelves-finally.655528/ )

I have to have a proper look on locations, but there is a double socket very close to where these uprights will be, I'm wondering if they should be earthed "just in case", "somehow" at "some random point" a power cable comes into contact with it. The shelf arms are metal by the shelf itself will be MDF

TIA

 

[EFLImpudence]

but there is a double socket very close to where these uprights will be, I'm wondering if they should be earthed "just in case", "somehow" at "some random point" a power cable comes into contact with it.

How do you think that is possible?
Wires do not just come out and make a determined effort to burrow to the nearest piece of metal.

If that is 'likely' then the decision is yours.
I would say you should ensure that it is not likely.

Other than that they should not be earthed.

 

[Cinobite]

Thanks for the input. Yeah, I wouldn't usually, but after learning various things on the topic through these threads (like connections can't be plastered over) I just wanted to double check in case there was some regulation - better to know than not right.

I can't ever see it happening, but let's, for example, say some idiot has the house after me or moves in and drills into the wall, it could expose a wire and if that touched the upright it could electrify the parts or the shelf that are sticking out the wall.

 

[EFLImpudence]

You have to decide which is the more likely:

That -

or someone touching a live part (faulty appliance or frayed lead) while touching the earthed metal.


Earthing is not a good thing in its own right; it is a compromise to disconnect the supply when a fault occurs whilst providing a low impedance path for current (through the body).

 

[PBC_1966]

Earthing is not a good thing in its own right

An common example of avoiding such being the transformer-isolated shaver outlet in many British bathrooms. The idea is that without the supply being referenced to earth, if somebody should happen to contact one side of it while simultaneously in contact with something which is earthed (tap, radiator, sink full of water with earthed drain at the bottom etc.) there can be no current flow through the body.

Not sure if it's done in the U.K. these days, but another example is the similarly isolated supplies used in hospital operating theatres here in the U.S.

 

[Adam_151]

Not sure if it's done in the U.K. these days, but another example is the similarly isolated supplies used in hospital operating theatres here in the U.S.

I'm lead to believe that an IT earthing system is employed in such areas, though its not something I have first hand expierience with. Anyway don't they call it an Operating room, rather than theatre over there?


BTW, there is a thread on outside of the UK from someone your side of the pond that might benifeit from your input

 

[PBC_1966]

I'm lead to believe that an IT earthing system is employed in such areas, though its not something I have first hand expierience with. Anyway don't they call it an Operating room, rather than theatre over there?

Both terms seem to be widely used. The most sensitive supplies are completely isolated from earth and provided with ground-fault indicators.

BTW, there is a thread on outside of the UK from someone your side of the pond that might benifeit from your input

Just replied to it, for what it's worth.

 

[Cinobite]

Turns out the struts could be placed well away from the sockets anyway. I turned the power off (as I frequently do when drilling into walls near sockets) and there was nothing to be seen when I opened the wall up. Incidentally my "AC wire detector" said there were no wires near the sockets but the entire second wall was live - as it usually does. Another item that shouldn't be allowed to be sold IMO

 

[PBC_1966]

Incidentally my "AC wire detector" said there were no wires near the sockets but the entire second wall was live - as it usually does. Another item that shouldn't be allowed to be sold IMO

I would never bother to get one. What I find objectionable is the way that certain devices are promoted to the general public, leading many people to believe that they are infallible when they are not (to put it mildly in the case of things like neon screwdrivers and non-contact voltage detectors).

Even devices which do have valid uses and which do certainly provide an increased level of safety can be subject to this problem. For example, I long felt in Britain that the RCD was promoted in some quarters in such a way as to leave many people with the impression that it's impossible to sustain a dangerous electric shock on any RCD-protected circuit. That's simply not true.

 

[Cinobite]

I completely agree, since buying this house and starting to modify/decorate I've come across a number of questionable tools.
The AC detector has to be the worst, I read reviews and they seemed hit or miss, bought one with the best reviews at the time and it is awful, I only use it sometimes for a laugh to see what it says. It will say there are no power cables around a double socket, even if a lamp is plugged in and on, yet an outside wall with no sockets or switches is live all over the plasterboard.

I bought it to check as I was installing a metal shelf above some sockets in the bedroom. Logic told me the cables should go down - but I wanted to double check. The detector said there was nothing below, live cables 1ft above. Ignoring it, I opened the box to check with my eyes and, sure enough, they did go down and not even close to what the detector said.

Now I picked the direction of cables in a wall up when I was about 6, watching my dad do DIY. But those detectors are marketed to let members of the public pickup and use and with such a bad performance, people are inevitably going to drill into live cables! I'm honestly amazed that they are allowed to be sold

 

[Risteard]

No, 13A is too big.

Too big for what?

 

[Cinobite]

^^ It was in reference to a string of 240v LED downlights