using flex for fixed installs

[hxsarge]

I've always been told that flexible cables cannot be used as fixed wiring in an installation, but I never realy considered my use off yy and sy flex. Can these be used for fixed wiring of machines/air con etc? I usually get the current carrying capacitys from manufacturers.

 

[wicksy]

If your cable meets the conditions etc you can use it.

SY is used a lot in industrial

 

[Evans Electric]

Well thousands do use it for that kind of work but as far as I know , the braid doesn't meet the cross sec. area to be used as an earth , so , IMO always use the G/Yell core .

The braid has to be earthed , I hasten to add.

And I note you have the same problem in trying to find the current ratings for SY .

I think the flex thing refers to PVC flexes in domestic work , used for fixed wiring.

 

[wicksy]

I'm sure RS components will have a data base on all the cables Evans

 

[Evans Electric]

Ah thanks Wicksy, I've had to ask the wholesalers to find out in the past . Think it was 6mm X 5 core I wanted. I have a list somewhere now.

 

[Andy™]

nothing wrong with using flex for fixed wiring. i use flex a lot for downlights. in certain circumstances, regs do state flex must be used. just remember to use ferrules on the connections

anf flex has its own tables for CCC & volt drop 4F2A & 4F3A

 

[Sidewinder]

SY should be rated as BS6004 flex.

Actually the braid does not "have" to be eathed, according to certain sources, though IMHO, only a fool would not earth it supply end.

I use it a lot for final connections to machines, p.b. stations etc & external wiring on machines and machine interconnections through building areas on distributed machines, though most of this does not come under 7671, it can be used,IIRC, I "used" it on my 2400 project for some final connections.

 

[hxsarge]

Yes, I use it a lot in industrial/ commercial jobs, normally with a proper brass gland at least at one end. I sometimes use yy as fixed wiring within large domestic heating systems, just because it's easy than 2 cables.

 

[sparkydude]

We have just finished working on the brand new engineering and computer building for Coventry University , and almost every final circuit is wired in LSF YY flex on basket/tray/galv conduit. The whole lots on show so had to be done with care and consideration for the final look.

Apparently the NICEIC inspector was not very happy as the lads doing it , stripped it down to cores as it entered the dis board header trunking, he would have preferred to have seen it sheathed as far as entering the DB , picky git LoL,

Nick

 

[VoltzElectrical]

I asked this question once having been told that you can't use it (ordinary flex) to wire say, a house for example. However, the CCC and voltage drop figures are there in the regs for design calcs so as far as I know,if you had a load of flex available in the correct sizes, then you could wire your whole house in flex if you wanted to.

 

[Steve3948]

I'm sure the 14th said flexible cables should not be used for fixed wiring, on the grounds that the bare earth served a purpose in that if the cable is damaged it will short circuit sooner than it would if it had an insulated earth.

 

[VoltzElectrical]

I'm sure the 14th said flexible cables should not be used for fixed wiring, on the grounds that the bare earth served a purpose in that if the cable is damaged it will short circuit sooner than it would if it had an insulated earth.

Interesting, never thought of that. What do the 17th edition say on the matter?

 

[Andy™]

Apparently the NICEIC inspector was not very happy as the lads doing it , stripped it down to cores as it entered the dis board header trunking, he would have preferred to have seen it sheathed as far as entering the DB , picky git LoL,

Nick

what he 'prefers' has nothing to do with it. providing its to the regs, he cant do anything about it

 

[Sharpend]

That is the trouble with the NIC, it always seems to be what they prefer as opposed to what the regs say.

 

[jockspark]

I'm sure RS components will have a data base on all the cables Evans [/quote

Maybe this link will help

Cable Current Ratings

 

[IzzyS]

I've always been told that flexible cables cannot be used as fixed wiring in an installation

Sounds like you have been misled. There is no regulation that says flexible cables must not be used.

What if your installation is a caravan or a mobile unit?

Where the installation (or part of it) is subject to vibration, you must take account of this in your design - solid conductors are not suitable, so the alternative is...?????

 

[Evans Electric]

Its horses for courses.... I used to do work on overhead cranes .....couple of things I remember , all wiring is multi-strand flexible because of the movement of the crane .

 

[Sidewinder]

Deke,

This is true about all rotating machinery mate.

Class 1 & 2 conductors are only acceptable within the fixed wiring in buildings.

 

[adammid]

Steve3948 I like your comment about the earth not being earthed in normal twin and earth and therefore shorts out if damaged than it would if the earth was sheathed. I was thinking about this only a few days ago. I worked in New Zealand a couple of years back and all of their twin and earth has a sheathed cpc. They are also allowed to run their cables ANYWHERE in walls and use 230/240 volts on site, but that's another story!