Electrical Shower issue

[Dartlec]

Don't mention AFDD, s. Bad for my blood pressure. Watched a seminar on it yesterday. Despite having a "recommended status" only it's being made clear that REC,s are expected to really work hard to emphasize this product to customers. The one question I keep asking about AFDD, s is, how did they just suddenly appear out of nowhere and so quickly become vital to have. All feels a, bit rushed

Far be it for me to suggest that RCDs were getting cheaper so less profit to be made from them by the manufacturers, and here was a technology that they could slap higher margins on...

The US has had them for ages, but I believe that they are more beneficial there with their voltage and wiring setup.

 

[pc1966]

I know that I had to search it out myself and still end up not 100% clear where there is a mixture of stuff.

As you say it is not always obvious. But for me it is the bath/shower setup that is the greatest risk. A towel rail out of reach from the bath less so, but if in hand's reach (which is what most would want after all!) it would be the same and I would like to see some supplementary bonding:

• shower - bath fittings - railing

Just in case!

 

[LastManOnline]

As you say it is not always obvious. But for me it is the bath/shower setup that is the greatest risk. A towel rail out of reach from the bath less so, but if in hand's reach (which is what most would want after all!) it would be the same and I would like to see some supplementary bonding:

• shower - bath fittings - railing

Just in case!

Am a big fan of supplementary bonding. If all else fails its a, great backup and usually very economical to install

 

[pc1966]

Often it was installed but some plumber in their infinite wisdom decided to cut/disconnect it

 

[Dartlec]

As you say it is not always obvious. But for me it is the bath/shower setup that is the greatest risk. A towel rail out of reach from the bath less so, but if in hand's reach (which is what most would want after all!) it would be the same and I would like to see some supplementary bonding:

• shower - bath fittings - railing

Just in case!

I did find a kitchen sink bonded a week or so ago - definitely done after 1984 or whenever it was that they dropped it. Usually no way to (neatly) bond a fancy towel rail though, even if you wanted to, so has to rely on access outside the bathroom or under the floor.

 

[LastManOnline]

I think we might be talking at crossed purposes.

For electrical installations "extraneous parts" are defined as things that are present within the installation, but are able to introduce a potential (which thankfully is usually 0V true Earth). All of them should be bonded to the supply MET so within the installation you would see resistances of the order of 0.05 ohm or so.

Now outside, where you might be in contact with the Earth via feet in mud or hand railings, etc, those parts could well be raised under fault conditions to a point you would notice due to, for example, the 75 ohms resistance to Earth and some fault current.

But for anyone inside they should not see this.

I have seen 'functional earths' on some RCBO (Hager commercial 10kA range) which I believe was intended to trip them on L-N reversal (or open N fault) but I don't see a great benefit from this if the earth arrangement is sound. Certainly the majority of RCBO do not have this. I my case I terminated to N so N-E IR testing would be safe and as expected.

Yes. I should have been clearer in describing what I said. Electric showers appear to be using the CPC as a functional earth (which they are entitled to do here). It creates problems here on TT systems (very few of these, left here) especially TT systems with a high res electrode. Just wondered if you experience that much in the UK. I should add that the problem is more usual to an older installation with a shower tray lying on concrete. In a modern house this leakage would not be noticed due to wooden floors etc

 

[pc1966]

I should add that the problem is more usual to an older installation with a shower tray lying on concrete. In a modern house this leakage would not be noticed due to wooden floors etc

OK that makes sense.

I can't say I have heard much about that sort of an issue, I guess it is just not so common to have a shower on concrete so it has its own leakage path to Earth to notice the difference on the supply MET potential.

If planned that way I would try and get some rebar in it and bonded to that! Alas, it never is planned...

 

[LastManOnline]

OK that makes sense.

I can't say I have heard much about that sort of an issue, I guess it is just not so common to have a shower on concrete so it has its own leakage path to Earth to notice the difference on the supply MET potential.

If planned that way I would try and get some rebar in it and bonded to that! Alas, it never is planned...

What's interesting is I have dealt with

OK that makes sense.

I can't say I have heard much about that sort of an issue, I guess it is just not so common to have a shower on concrete so it has its own leakage path to Earth to notice the difference on the supply MET potential.

If planned that way I would try and get some rebar in it and bonded to that! Alas, it never is planned...

What's I find interesting is that this situation doesn't occur more often in the UK,especially in TT installations. Here's my reasoning on it. When we investigate a call from someone who has suddenly started getting a "tittle" (or something a little stronger) we always find it's the same cause. An older home that is un-neutralised , basically a TT installation where overnight a low impedence earth has become a high impedence earth either by a plumber replacing a copper service with a plastic one or the Water services upgrading their pipes to plastic.This leaves only the rod as the main earth which is never more than a 4 ft rod and is untested. The shower tray is either is either on a concrete floor or is in contact with metalwork.
The solution is provided by arranging to get the DNO to provide a, Neutralising link.
I think that in the UK your TT Installations are likely to have lower impedence earth rods because from what I read you guys are not happy with anything over 200 ohms. I think that may be a major factor in these "shower shocks" been less common. I am open to correction here.

I have contacted both Triton and Mira for confirmation that they use the CPC as a functional earth as well as a protective one. I need to do that as as I have to write a report for one landlord. They have so far been a little reticent to respond. In fact according to the regs here they are entitled to do that. I just want to nail it down so I can put it in writing

 

[Mike Johnson]

TT installations are becoming rarer in the UK, but are the norm in France where the regulations require a reading under 200Ω and is generally wanted below 150Ω trouble is this would only be checked on a new installation or on the sale of the property, and even then a Ω check is not done, just a visual check that an earth rod is in place.

 

[LastManOnline]

TT installations are becoming rarer in the UK, but are the norm in France where the regulations require a reading under 200Ω and is generally wanted below 150Ω trouble is this would only be checked on a new installation or on the sale of the property, and even then a Ω check is not done, just a visual check that an earth rod is in place.

They must have a lot of confidence in the conductivity of their soil?

 

[Mike Johnson]

They must have a lot of confidence in the conductivity of their soil?

The majority of new builds in France are supplied with a mesh/grid system of Earthing surrounding the house, becoming rare to have rods now except on older properties, which is the majority in rural France.