Flexi Cable And Solid Cable.

[mellykp1]

hi everyone I have a question to do with a theatre light circuit all I have is a picture a college sent me showing 16 flexi cables with lighting plugs on the end which the school plug into a lighting desk, the school wants to switch to a dmx led lighting system, my question is I am not sure if the flexi cable runs up the wall into the ceiling to the plug sockets on the lighting bars, to switch to led I have to swap the existing lighting sockets on the lighting bar to conventional 240v plug sockets and at the other end all the tails that plug into the lighting desk to run into a new db box, My problem is can I extend the tails with more flexi to the db box or would I have to replace all the flexi cable with solid from the lighting bar socket right down to the new db board. I always thought that flexi cable was classed as none permanent  and solid as permanent, is there any way that I can join the flexi to solid and still be with in the regs. As I said I only have a pic to go by, I am based in the midlands and my college is down south so I can not look for myself and if all the flexi has to be replaced with solid then its a much bigger job.

thanks

mel

 

[binky]

SWA, meter tails, and earth cable are multi-stranded 'flexi' cable. You wouldn't regaard any of these as non-permanent.

 

[Andy™]

7671 allows fine stranded flex to be used for fixed wiring. in some cases, it is a requirement

 

[Steve3948]

7671 allows fine stranded flex to be used for fixed wiring. in some cases, it is a requirement

Where might that be then.

 

[Andy™]

Where might that be then.

installations subject to vibrations.

dont have current regs here, but 717.52.2 in the red book for a start.

 

[Steve3948]

installations subject to vibrations.

dont have current regs here, but 717.52.2 in the red book for a start.

That section relates to  "Mobile or Transportable Units"

 

[binky]

which is a more adverse environment than an house, ergo flex is good for anywhere. No doubt there are exceptions to that, but I can't think of any except busbars.

 

[Andy™]

That section relates to  "Mobile or Transportable Units"

yes, your point being?

 

[Steve3948]

yes, your point being?

For connecting to the Fixed installation, not part of the Fixed Installation, i.e Mobile/Transportable Unit.

 

[Andy™]

you will find 717.52.1 is for the connection of the unit. 717.52.2 is for the internal wiring

 

[binky]

as long as the cable is suitable rated for the load, correctly protected, and suitable for the enviroment, it matters not whether it be flexible, FTE, FP or MiMS. Not that I would want to wire a house in MiMS.

 

[Steve3948]

you will find 717.52.1 is for the connection of the unit. 717.52.2 is for the internal wiring

I don't agree that whole section 717 is for Mobile or Transportable, says nothing about fixed installation.

 

[Marvo]

I don't know what the rules say but I wouldn't see a technical reason not to use stranded as long as all the light switches, sockets, MCB's etc have terminations that are specified as okay for stranded flex wiring.

 

[mellykp1]

Hi thanks for all the replies, so are you saying its ok to take the plugs off the flexi and extend the tails with the same rated flexi to a new db

Thanks

Mel

 

[binky]

sound fine to me

 

[SPECIAL LOCATION]

Flexible cables are permitted to be used in fixed wiring..

In addition to Andys ref of the section  717..

Reg 521.9.1  page 122.... its been a standard reg for ages...

Providing essential safety considerations are observed then flex can be used as fixed wiring. 

One reason why we don't is that it is more susceptible to damage during installtion..

But that doesn't mean you cannot use it

521-01-04 was one of the old money equivalents!

 

[mellykp1]

Thanks guys for all your replies sorry if it sounded like a stupid question but since passing my 17th edition a few years ago i haven't had anyone to turn too for advice, thanks again

 

[Marvo]

I don't think it was a stupid question by any means, it's a somewhat contentious area by the sounds of things and I think all the comments and views sounded valid even though some got descoobed for some strange reason.

 

[binky]

Inappropiate de-scoobs sorted. If you ask me stranded cables are superior to soild core, hence they get used for more extreme environments like boats, vehicles and outdoors. IMHO biggest problem is people being 'stuck in a rut' and not thinking 'outside the box' a little more often. Everything we used in my Aerospace days was stranded, and tinned for that matter - proper cable. The DC cable is stranded and tinned aswell, and that is out in all weathers.