SY, CY None Compliant????

[HappyHippyDad]

So, I'm out on site the other day and the apprentice is installing some SY cable for a ring final circuit. Anyway, we got chatting and he mentions that this type of cable does not comply with BS7671! I said, "of course it does, it's part of the AM2 and it is one of the 7 cable types of the new 2357 apprenticeship NVQ! So out of curiosity I had a look. To my suprise, it does state in the BS7671, that this type, along with YY, CY are none compliant!! I know that most of this multi-core cable comes with none standard colour cores etc but does any one know an actual reason why it is none compliant? I am genuinely interested.

Cheers

Jay

Could you point me to the page or reg of BS7671 where it says this JS? I'd be interested to read it, thanks.

 

[GEOFF S]

Could you point me to the page or reg of BS7671 where it says this JS? I'd be interested to read it, thanks.

Hi

Im pretty sure its comes down to the braided screen not meeting the relevant requirements for mechanical protection, also probably issues with regard the braid and fault current.

Cheers

 

[shanky887614]

go be honest as long as its used inside and it doesnt require mechanical protection 3c (L,N,E) sy is fine.

to be honest most of it ive used has been in trunking from vsd's to motors with a stuffer out of the trunking then into the motor case

Sent from my SM-G935F using Tapatalk

 

[davesparks]

Could you point me to the page or reg of BS7671 where it says this JS? I'd be interested to read it, thanks.

Somewhere there is a reg which says that heavy duty flex is to be used for installation work, and SY doesn't fall in to that category

 

[Adam W]

.... seen plenty of live un- earthed braid on this stuff over the yrs ...

I've found loads of this at my place, which was installed by the mechanical guys. It gets my goat - why even bother if you're not going to earth the braid? You may as well just use H05.

IMO SY has it's uses, such as where you need something more flexible than SWA but there is a danger of someone going through the cable with anything - if the sheath is earthed contact will be made with that before a live conductor so the protective device should operate.

 

[Flanders]

I thought the brade was for a screen and not designed to carry a fault current thats why is has a seperate cpc within the cable.

 

[Davisonp]

Somewhere there is a reg which says that heavy duty flex is to be used for installation work, and SY doesn't fall in to that category

[h=5]521.9 Use of flexible cables[/h]521.9.1 A flexible cable shall be used for fixed wiring only where the relevant provisions of the Regulations are met. Flexible cables used for fixed wiring shall be of the heavy duty type unless the risk of damage during installation and service, due to impact or other mechanical stresses, is low or has been minimized or protection against mechanical damage is provided.
NOTE : Descriptions of light, normal and heavy duty types are given in BS EN 50565-1.

 

[Adam W]

I thought the brade was for a screen and not designed to carry a fault current thats why is has a seperate cpc within the cable.

You can have a separate CPC within an SWA, but the armour should still be earthed.
Either way the braid of SY flex should be earthed.

 

[davesparks]

I've found loads of this at my place, which was installed by the mechanical guys. It gets my goat - why even bother if you're not going to earth the braid? You may as well just use H05.

IMO SY has it's uses, such as where you need something more flexible than SWA but there is a danger of someone going through the cable with anything - if the sheath is earthed contact will be made with that before a live conductor so the protective device should operate.

But the braid is not rated for the fault current, so it is pretty much the same as installing PVC insulated and sheathed flex as far as any protection goes.

 

[davesparks]

You can have a separate CPC within an SWA, but the armour should still be earthed.
Either way the braid of SY flex should be earthed.

Earthed yes, but it cannot handle fault current so cannot be used to provide any protection such as that provided by SWA, MICC or any bs8436 cable