Re: Shower cable in a copper pipe ??

[Wanderer]

All,

> I currently have cable running to my shower through sealed conduit attached > to the top of the skirting board in the bathrooom - the design of the flat > precludes passing it through the walls. It is safe / allowed for me to use > chromed copper pipe for this instead as it will look a lot nicer and fit in > better with the other pipes in the room ?? Safety etc says it may not be....

My immediate thoughts would be that as long as the pipes were properly bonded there isn't too much of a problem. What always bothers me about these types of arrangements, however, is that at some time in the dim and distant future, when you no longer own or rent the flat, someone will come along and think that it's a water pipe running along the top of the skirting and merrily cut into a live cable.

Reminds me a bit about a quite elderly edition of GroundFarce, where Charlie 'Nipples' Dimmock was feeding a section of cable for a water feature through some scrap gas service pipe under a path. I complained at the time to the Beeb, but never heard any more about it.

[NC]

Good point - we have just bought the flat and will be in there for a few years - I will ensure I label it somehow to ensure that I / next person knows whats in it !! Thanks

[fred]

It's not something I would do myself, an accident waiting to happen, but if you _must_ then I suggest drilling a small/medium sized hole in the pipe in an obvious but unobtrusive position to give the next owner a chance to see that it couldn't possibly be a water pipe.

[NC]

A good plan.. but then you have to hope they see it, and you've then not got a waterproof cable-feed... ??

[Andrew Gabriel]

It used not to be allowed to use exposed metal truncking, but that restriction seems to have gone from the 2001 regs. Obviously, it will have to be bonded.

[NC]

excuse my ignorance - but what do you mean by 'bonded' ?? earthed ??

[BigWallop]

We knew what you meant. :-))

[N. Thornton]

Hey, it could be worse. For a moment I was half wondering if the copper pipe was going to be the one that carried the water to the shower as well!

Regards, NT

[Andy Dingley]

Bonding is like earthing, but without the earth !

All metal parts (pipes, shower rails, bathtubs) are connected together with green & yellow, and this is connected to the earth terminal of the supply to the room. There is no need to run a separate earth connector for this metalwork, back to any centralised earth. Nor does this bonding conductor need to be as large as many earth conductors do.

The difference between bonding (or equipotential bonding) and earthing is in what they're trying to achieve.

Earthing is there so that when a live-case fault develops, enough current flows through the earth terminal to blow the fuse or breaker supplying the equipment. Impedances must be low, or there won't be enough current to blow the fuse - which is why it's important to test earth loop impedance, not just rely on a neon tester.

Equipotential bonding is there so that no two metal objects can develop a high voltage across them. This is typical from a high impedance fault condition - maybe a heater with failing insulation, not enough to cause an earth fault, but still enough to make the case give you a shock. Humans are normally high impedance, so won't suffer such shocks - but wet humans are much more conductive, so bonding becomes especially important in bathrooms.

[Steve]

If you say "Shiny metal conduit" instead of "pipe" it should make you feel better.

Steve

[Chris Oates]

or to look at it another way.... (a)even more paths for across the chest shocks (b)more things that can become live

you are not allowed bare protective conductors but you can have acres of bonded metal

where I work bonding causes more problems than it solves because it just increases the chance of electrucution

Isolation, insulation & electronic protection !

[Wanderer]

Err, are you suggesting that the Faraday Cage doesn't work? So how come most leccy companies now do so much 'hands on' live working?

[N. Thornton]

Hi.

A bathroom is not really like a faraday cage, since it has mains in there that is not at the 'cage' potential. Its more like an earthed cage with wired appliances in it, which occasionally become live.

2 issues with equipotential earthed bonding are:

a) a shock from light fitting to bonded metalwork is worse than a shock from light to unbonded metalwork and b) should there be a fault with the earth feed lots of metal will become live instead of a little.

Those points dont make it bad, but they do make it less great than it first looks.

But I would look at equipotential bonding from another point of view...

How many lives has it saved? Our of 50 deaths per year from electrocution in the UK, how many of those were bathroom electrocutions? And how many of those would have been saved by equipotential bonding?

Now, whats the cost of equipotentially bonding the nations bathrooms? How much per life is that?

Now, people die en masse due to their own ignorance, eg due to stupid eating habits. How much would a food education campaign cost? How many lives would it save? How much per life is that? How many times the number of lives would be saved with the same amount of money?

Regards, NT

[Andy Dingley]

A campaign to bond all the nation's bathrooms tomorrow "For The Sake Of The Children (tm)" would be expensive.

But a better standard that all new work should comply with, is a much lower incremental cost.

[Neil Jones]

Isn't that how Aqualisa's Quartz shower works?

Neil

[Wanderer]

Occasionally? I hope not.

So you're suggesting that PME is not worth bothering with? May I respectfully suggest that you need to go away and quietly reflect on just what it is you're saying.

*If* an appliance or wiring installation develops an earth fault then the various safety measures *should* act to isolate that fault.

If they don't, then the whole fabric of the building rises to some voltage above zero with respect to earth, coz the leccy companies connect the neutral of the distribution system to earth at the transformer. Because you in your dripping wet state are safely contained within a Faraday cage, formed by the equipotential crossbonding of the installation, the risk of electric shock is minimised, because you are at the same voltage as everything around you.

Please don't.

[Gel]

[Stuart]

Or ,seeing the hole in the pipe,they might think it is an unused water pipe and STILL cut in to it . maybe better putting some of that hazard tape round it with suitable labelling warning of what lies within !!! Stuart

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Remove YOURPANTS before E-mailing Me

[N. Thornton]

Of course it does, faults happen, thats why aditional safety measures are needed.

No, I haven't criticised PME.

Indeed, they shuold. Domestic wiring regs also cover situations where safety measures dont resolve the problem, due to the protection measures being faulty. Multiple protections is the approach.

No it doesnt, if an appliance develops an earth fault you may be shocked by current passing from appliance case to concrete floor, metal door frame on damp bricks, etc.

Right, but even a live 'earth' feed wont make the whole fabric of a building live, it would introduce numerous potential electrocution situations within the building.

You seem to be forgetting that faulty light fitting above you as you get out of the bath.

Pretty significant point.

Regards, NT

[fred]

LOL

Yeah, know where you're coming from, but I see a 'pipe' I turn off the water, I see a 'conduit' I turn off the power :-)