I once had some wiring done in some PVCfree electric cable (around 10-12 years ago) which was red in colour and also did not emit an electric field, but I cannot remember the name and would be grateful if someone can tell me. It was available locally.

I am about to have some new rewiring done this week and need to know ASAP.

Many thanks.

Thanks. I believe the cable I used before did not emit the electric field but did emit the magnetic field.

"Ordinary grey Twin and Earth domestic cable will usually be cross linked polyethylene by default (ask for 6242B with BASEC approval)." Does the grey cable contain no PVC nowadays then? I don't have a problem with polyethylene.

Well I guess we are into a very esoteric debate about Electromagnetic radiation there, in terms of electric and magnetic fields but if someone told you it was zero emission then I think you were sold a pup - that said, teh level of radiation in a domestic environment is approaching zero and there is no real evidence it's harmful to humans

As for modern cable types, yes, in most cases PVC has been replaced with XLPE as an insulator and oversheath.

regards

Barney

You can cut it down but the only way you can eliminate it is to turn it off - as I said, the emission is low level and there is no evidence to suggest it's harmful.

There is probably a bigger dose from sitting in front of your PC or using a mobile phone.

regards

Barney

Carolwat,

Where is local in relation to you?

What sort of cabling? Power, audio ,data?

More info is required to help you

Tonyt

Tony, it is for electrical work in my house, some rewiring of cables to lights and some plug sockets etc. and I am in Sheffield. I just need to tell the electricians what to get. I am ill and have chemical sensitivities so need to be careful of things like PVC.

Having cables which emit reduced electrical fields is a nicety rather than a necessity - its the PVC which is the biggest problem. But the stuff I used 12 years ago definitely emits a greatly reduced electric field cos I measured it with an emf meter - the magnetic field was not reduced at all.

I am actually wondering whether it was 6242B suggestd above that I used before - I think it had a "6" and a "B" in it anyway. It was the AECB who suggested the cable I had before, around 10-12 years ago, but they were unable to help me this time when I asked them as they no longer give advice and I don't seem to be able to post on their forum - think there is a glitch.

EMF - electro magnetic force , they are all inter related , I believe you cant have one without the other.
LSF may be PVC free but could contain chemicals harmful to the environment .

If you wish to reduce EMF people suggest using radial circuits rather than rings , easily achievable by splitting the ring in the approx. middle and placing each side on a lower rated MCB ( 16 amp ) electrian will know how

Posted By: davidfreeboroughmaking sure the system is only earthed at one point close to the consumer unit

Think that can contravene Part P and best practice in a lot of circumstances. Earthing is one of the reasons a 'Ring' is used isn't it (not the only reason and not the only way to earth I know).

<blockquote><cite>Posted By: davidfreeborough</cite>making sure the system is only earthed at one point close to the consumer unit</blockquote>

That would presumably rule out metal back boses and metal light switches? Metal back boxes are normally screwed or just plastered into the wall which can be a reasonable earth?

Interesting question. Stakes in the ground (or elertic fence braid in a puddle) are surprisingly good earths (damp soil/rock is around 400Ohms IIRC) but as soon as the substrate is dry (internal plaster is definately dry) then resistance can rise dramatically. I wouldn't expect a metal patress in a plaster/masonry wall to be much good as an earth. Your bulk conductor isn't huge (wall width) and dry plaster is probably a terrible conductor, even though you will get a reasonably good surface-area wetting between plaster and patress.

If your cable was red, I think James Ingram was right. This stuff is also known as FP200 and as far as I know, it's the only mains wiring cable generally available in a red sheath. Another type of fire resistant cable, MICC (mentioned by docka above), may have an orange sheath but it has been largely replaced by FP200.

Usually red FP200 is used for alarms and white FP200 for emergency lighting, though there's nothing to stop you using either colour for general wiring. It has an aluminium inner sheath which is part of its fire-proofing. If earthed, the sheath would reduce the electric field around the cable. I'm trying to recall the installation method but I don't think the ali is normally earthed so I'm afraid you are not guaranteed an effective shield.

The usual choice for PVC-free wiring is LSF (low smoke and fume), for which the standard is 6242B. It's white. Grey cable is normally 6242Y and PVC sheathed and insulated, and it's what electricians will fit unless you ask for something else.

Tony

"The wires in the wall are humming" - Joni Mitchell, 'Edith and the King Pin'

I once took a training course on measuring EMF produced by various pieces of electronic equipment.

Method 'A' is to put the test piece in a Faraday cage to filter the background noise, and then test. Fine if you have a big enough Faraday cage.

Method 'B' is measure the background noise across the spectrum, then turn on the equipment to be tested, measure again then subtract the background from the test data to give a result.

From carrying out method 'B' many times in different locations I can tell you for certain that the EMF from your cables is not going to be significant.

Also all appliances are CE marked so have to emit a limited amount of EMF and have to be resistant to a level of EMF also.

As a matter of interest ring circuits were introduced as a compromise to reduce the amount of copper required

Posted By: CWattersI once demonstrated how rubbing a screwdriver against a bit of metal was enough to prevent a nearby radio reciever working correctly.

Can start a camp fire by doing the same with Boy Scouts knees I have been told

Reminds me of this strange report of a "force field" being created at a 3M factory...

http://amasci.com/weird/unusual/e-wall.html

David Swenson of 3M Corporation describes an anomaly where workers encountered a strange "invisible wall" in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This "invisible wall" was strong enough to prevent humans from passing through. A person near this "wall" was unable to turn, and so had to walk backwards to retreat from it.

This occurred in late summer in South Carolina, in extremely high humidity. Polypropelene (PP) film on 50K ft. rolls 20ft wide was being slit and transferred to multiple smaller spools. The film was taken off the main roll at high speed, flowed upwards 20ft to overhead rollers, passed horizontally 20ft and then downwards to the slitting device, where it was spooled onto shorter rolls. The whole operation formed a cubical shaped tent, with two walls and a ceiling approximately 20ft square. The spools ran at 1000ft/min, or about 10MPH. The PP film had been manufactured with dissimilar surface structure on opposing faces. Contact electrification can occur even in similar materials if the surface textures or micro-structures are significantly different. The generation of a large imbalance of electrical surface-charge during unspooling was therefor not unexpected, and is a common problem in this industry. "Static cling" in the megavolt range!

On entering the factory floor and far from the equipment, Mr. Swenson's 200KV/ft handheld electrometer was found to slam to full scale. When he attempted to walk through the corridor formed by the moving film, he was stopped about half way through by an "invisible wall." He could lean all his weight forward but was unable to pass. He observed a fly get pulled into the charged, moving plastic, and speculates that the e-fields might have been strong enough to suck in birds!

The production manager did not believe Mr. Swenson's report of the strange phenomena. When they both returned to the factory floor, they found that the "wall" was no longer there. But the production workers had noticed the effect as occurring early in the morning when humidity was lower, so they agreed to try again another day. The second attempt was successful, and early in the morning the field underneath the "tent" was strong enough to raise even the short, curly hair of the production manager. The "invisible wall" effect had returned. He commented that he "didn't know whether to fix it or sell tickets."

and a great example that it's the current that kills you, or rather, it's not the volts that kill you! :)

Anybody get to stand on a plastic bucket at school and wind a Wimshurst machine? I guess elfin-safe tea prevents that nowadays, along with the great fun we had rolling little balls of mercury around the desktop.