Sy cable question

[nathansinar]

Hi guys new to the forum and will introduce myself shortly

I have attached an image of a spur i have taken as you can see from the attached image

I am doing a trainee maintenance engineer role and just wanted some info on the below.

1.) when using sy cable do you have to earth the sheeth? i have had various reponses saying it is good practice but you can get away with using the cpc inside the cable and that alone?

2.) in the image i have posted becuase the sheeth hasnt been used an earth from the the spur to what ever it is feeding, does an earth need adding from the back of the spur plate to actual spur box as it could become live?? is it a reg that this needs to be done?

Thanks for help!

Nathan

 

[Jamchiv01]

them's the correct glands for SY cable. braid is earthed and the cable is secured in the gland.

I meant the plastic glands he is using

 

[nathansinar]

I meant the plastic glands he is using

Thanks for the feedback i completely agree with what your saying i am only stating that ive been told you can use plastic glands and you dont always have earth the metal braid i agree its better but the im sure the regs dont state its a must do???

 

[nathansinar]

And the image i have posted doesnt break any regs

 

[Wilko]

And the image i have posted doesnt break any regs

Hi - there is a concern, as has been mentioned here - please have a read of this doc from a cable manufacturer.
https://www.edwardes.co.uk/uploads/uploaded_files/2016/03/15/SY-Control-Flexible-Cable.pdf

 

[nathansinar]

Hi
sorry cant open the link for some reason what is your point?
from the image i have attached their is nothing wrong with it i agree yes many will say to earth the braid but all i wish to know is

is it compulsory? and becuase i havent done so does an earth need running from the spur face plate to the actual fcu?

thanks

 

[Andy78]

And the image i have posted doesnt break any regs

Arguably it does. The way the cable is made off the metal braid is exposed, making it an exposed conductive part which should be earthed.
But, as has been said, it's the wrong cable for the job in the first place.

 

[Risteard]

The point is that BS7671 does not encourage the use of SY cable for general low voltage wiring, even with the correct glands being used (as they should be).

 

[Jamchiv01]

I briefly read the document and noticed this:

"SY control cables are not suitable for fixed wiring applications requiring compliance with the regulations set out in BS7671"

I believe this is what @Wilko is hinting at??

 

[Wilko]

Hi - yes Jamie, that's it. I was a bit surprised to read SY cable is not type approved to be used under BS7671 for fixed wiring, as stated by this manufacturer. @Risteard in post #12 reminded me (thanks buttton pressed).

 

[nathansinar]

i really appreciate the feedback and please dont think im saying anyone is wrong as i have said i have just started a trainee maintenance role within a company that deals with food packaging in my local area (fmg factory) and most sockets etc in our place use sy cable , and swa! but weve had some sparkys in putting in a new 100amp dist board and it was a question i raised and this was the awnsers i receieved from them

1.) does the braid need to be earthed? = " people have diffrent opinion but it is not a regulation"

and so on that image i dont need to run a seperate earth from the fcu to the back of the spur faceplate ??

 

[Jamchiv01]

You don't HAVE to run a separate earth but I HIGHLY RECOMMEND YOU DO, AS ITS GOOD PRACTICE AND TAKES A EXTRA FEW MINS AND A TINY BIT OF CABLE.

Again, I was taught to earth the Braid using the appropriate glands, but the braid CAN NOT be used as a protective conductor.

Terminate your SY like this:

This way you can sleeve the braid cream as its functional earthing and place it into the earth terminal. There's no harm in doing this and doesn't take much extra time either as you have to separate the strands anyway.

And in future run SWA not SY.

 

[nathansinar]

i agree mate and thats the way i have done previously i was only doing this from what another sparky advised me to do ...... hence me asking the questions because most of them are done like this around our place, This was something i found on the forum

" braid is designed for screening and not earthing. Unless required as a screen you won't find many electrical engineers earthing it but rather cutting it back and taping it before it goes through a plastic gland. As it is clear sheathed above and sheathed below, the chances of it becoming live following cable damage without the cpc getting hit also is pretty slim"

i just get different opinions i just wanted to know if it was a reg that the braiding has to be earthed/glanded or if it can be left like in the image i posted

also yes the spur is earthed from the main cpc side but i have been told it could still become live hence me raising the questions becuase the braid is not earthed

cheers

 

[nathansinar]

and sy can be used for fixed purposed i have seen it done in loads of place when i was an apprentice in another job, people have diffrent views yes swa is a lot tougher and people would say " better fit for purpose " but it can still be used all the wise every install i have seen must be crap and they cant all be wrong

 

[Barry White]

The braid should be earthed as its intended use is primary a control cable and the braid is used as a shield for electromagnetic interference. VSDs can give off a lot of interference which interfere with metal detectors and other sensitive equipment. The braid can be earthed at one end or both for higher frequencies.
That said the cable is often used as a rough service cable and often used as you have. the problem is widespread (I have used it in the past)
The worst electric shock I have had was from this type of cable the braid was not earthed and used as a trailing cable on a farm. A dog yelped as it walked on a board off a pallet. So suspecting a nail in the wood I picked it up touching the damaged cable which was live. my feet and hands were wet and I felt it hard.

 

[Jamchiv01]

As @Wilko pointed out: SY control cables are not suitable for fixed wiring applications requiring compliance with the regulations set out in BS7671 So there wouldn't be a regulation to specify in the first place.