Outside tap

[pirate]

I usually fit outside taps with plastic pipe through the wall. OK, it's not flush, but you simply use a 15mm compression elbow, then a short length of plastic pipe to another compression fitting into which the tap screws. The bib fitting needs to be spaced off the wall on a piece of wood. The whole assembly is more resistant to frost, and i fit stopcock internally, so when winter comes, switch off, take tap away, exces water drains out...and in Spring, it's 2 minutes work to re-assemble.
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Compression fittings on plastic pipe are your friend!
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Here's a pic...on this occasion I used a copper "stub" pipe, but the pipe through the wall is plastic. It's mounted on a chamfered teak backing plate. To me, it just makes sense to have a plastic pipe through the wall, and internal coupling is easier.

 

[davesparks]

That looks an awful lot like you've put PTFE tape on the threads of a compression fitting?
Thats a waste of time, and usually a sure sign of someone not understanding what they are doing.

 

[pirate]

Thank you for your comments davesparks!
Let's just agree to differ, ok?
There are times to use PTFE, and times not to use PTFE, and I suggest maybe you have not considered your response, but merely butted in with a comment that you believe to be correct.
I stand by my usage of it where circumstances indicate it is useful, and your suggestion that i don't know what I am doing is a little bit insulting.
I have plumbed scores of kitchens and bathrooms, used alternative methods where required, and am quite confident that the lack of problems means my methodology is fine, thanks.
I fully believe there are folks who will agree with you, and some who will not, but the simple fact is that PTFE is a perfectly acceptable adjunct for compression fittings, and without it many installations would fail. There are some who scoff at the use of Calor-Tite, but who owe their lives to that stuff...just don't dismiss the practices that us old codgers adopt, ok?
If you face a leaking joint under your floor, tell me you wouldn't try some PTFE as a first defence.
This isn't leaking electricity that can kill you, it's a sealing tape that can stop a leak, allow alignment of joints, take up some slack, allow for some extra tightening, and provide a better seal than metal to metal can provide in some circumstances.
OK, not perfect, but useful and perfectly acceptable in most (not all) circumstances.
I believe that quite a few people use it, and it was designed to be used with compression fittings, which are fairly common.
Finally, stating that I clearly don't know what i am doing is not helpful. This forum is for assistance, not criticism. I try to contribute where I feel i can, so if you have a constructive response to make, i look forward to hearing it.

 

[Zerax]

...but the simple fact is that PTFE is a perfectly acceptable adjunct for compression fittings

I agree with you Pirate... it's a very useful lubricant to the threads... makes tightening the nut easier.

 

[davesparks]

Thank you for your comments davesparks!
Let's just agree to differ, ok?
There are times to use PTFE, and times not to use PTFE, and I suggest maybe you have not considered your response, but merely butted in with a comment that you believe to be correct.
I stand by my usage of it where circumstances indicate it is useful, and your suggestion that i don't know what I am doing is a little bit insulting.
I have plumbed scores of kitchens and bathrooms, used alternative methods where required, and am quite confident that the lack of problems means my methodology is fine, thanks.

But you've put it on the threads, which do not directly form part of the seal so do not need any form of sealing material applied to them.
All of the sealing is done by the olive, the threads are purely there to allow the nut to compress the olive.
Sealing compound should be applied to the outer surface of the olive, and a wrap of PTFE there does work if that's all that is available.
PTFE is used on threads which form a seal, such as in screwed iron pipe joints, tapered thread connections etc.

The insult was intended.

Doing something incorrectly a hundred times over does not make it correct.

 

[pc1966]

I agree with you Pirate... it's a very useful lubricant to the threads... makes tightening the nut easier.

More importantly in 5 years - making it easier to loosen!

 

[7029 dave]

Just my tuppence worth, I would never use compression fittings under floors etc, only in surface situations in which are accessible, with gas pipes no compression is permitted unless its surface.

 

[Ray Pooley]

Hi all

I am on a TN-C-S / PME supply and have an outside tap, I have fitted it with 5 speedfit plastic elbows and a speedfit all plastic valve. So having so much plastic in place that should be the recommended insulated section of pipe to prevent dangerous voltages being on the tap in the event of a PEN failure

With the pipes full of water the resistance between the MET and the outside tap is 1726 ohms, so I work that out to be a potential current of 133mA which is still enough to be potentially fatal?

Please correct me if I am wrong here?

I know people say the risk of a PEN fault is so low you don't worry about it, but if it never happened why all the regulations for EV charging from PME, also I live in a very windy little village with individual overhead cables from the transformer down the street and UK power networks are often out to repair them. Information from UK power networks would indicate there is an electrode at the transformer and 2 more down the road, it seems the nearest to my house is 8 poles away and some of those poles look as if they could fall down lol, so if its gonna to happen anywhere I guess it would be here.

Thanks Marcus

Just curious. You say you have an "outside" tap which implies, to me at least, that the tap is connected to the building internal water supply network. In that case wouldn't it be covered by the existing bonding inside the building? Perhaps I don't understand your issue.

 

[marcuswareham]

Just curious. You say you have an "outside" tap which implies, to me at least, that the tap is connected to the building internal water supply network. In that case wouldn't it be covered by the existing bonding inside the building? Perhaps I don't understand your issue.

It is the bonding to the MET that would make it a risk outside in the event of a PEN conductor fault on the DNO network

 

[pirate]

7029 dave
I agree with you on that, with gas it is quite different.
Similarly I would never use push-fit under floors for water pipes...
We all have our methods, and sometimes we adopt new ones as time goes on
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Anyway, for what it's worth, and opening myself to ridicule once more, I finished an emergency plumbing job today, for an elderly couple, where the tiles in a bathroom had lifted due to poor workmanship by the joiner and tiler.
The client lifted the plywood, replaced with new, and then screwed 3 screws through the pipes below, 1 into the cold, 2 into the hot...not just nicking them, but right through and out the other side!
Emergency, as it was their bathroom and utility room...
This is the finished repair:

No give in the pipework so using plastic, whatever I had to hand, and davesparks will be delighted to see NO PTFE tape anywhere!
The bathroom is to be re-plumbed, and they want new lighting in the conservatory and in the garden, because the previous owner ( a well known footballer in his day) had a botched job done...so I have got both those jobs to do when the lockdown is lifted. If I require to do so, I will use PTFE tape as necessary. Just because it extends over the thread doesn't mean it isn't over the olives, but we have all encountered mis-matched fittings over the years.

And yes, I am fully aware the insult was intended, davesparks, but thanks for clarifying that for forum members who might have been in doubt.
However, I took no offence as I am well beyond that...I no longer need to care what people say...I just do a job.

 

[marcuswareham]

I did some tests with all the pipework disconnected and to my surprise, there was still conductivity through the wall although a lot less

I have now replaced the pipe through the wall with plastic instead of copper, and now got 1373 ohm between outside tap and MET, so much better and I guess the conductivity left is from the water.

 

[pc1966]

Some of that could be via conductivity in the wall to true Earth, you would need to have the internal pipe dry of water / disconnected to be sure which route the meter is measuring.