Earthing braid of SY cable

[yellowvanman]

If someone has not earthed the braid of an SY cable what reg can I quote as being infringed.

My thinking is that the braid (like SWA) is an exposed conductive part and needs earthing.

Is it 411.3.1.1?

 

[Darkwood]

Its actually original design is as a screening and not for earthing purposes but it has found itself been used as a protective rough service cable, the glands will be exposed so forming part of an exposed conductive part but it also in your situe has been used to provide mechanical protection i assume and thus its prone if damaged to been made live so should be earthed.

 

[Guitarist]

As darkwood says, it's 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.

 

[jeremy]

Will it still work as a screen if not earthed?

 

[Guitarist]

Again, as darkwood said, it may be designed as a screen but most of the time it is just used as a rough service cabling, like a flexible swa. To provide proper screening it should be connected at one end or both, depending on the frequencies/voltages etc.
RA EMC Awareness - Mitigation - shielding cables is worth a read.

 

[Silly Sausage]

Again, as darkwood said, it may be designed as a screen but most of the time it is just used as a rough service cabling, like a flexible swa. To provide proper screening it should be connected at one end or both, depending on the frequencies/voltages etc.
RA EMC Awareness - Mitigation - shielding cables is worth a read.

In that case you may as well use the correct gland, locks the braid in and stops it being pulled out.

 

[Andy 7671]

So...if you are told to use TRS glands, would terminating the braid in the MET or lugged at isolator be deemed as bad practice...?

 

[Darkwood]

I always ensure its earthed at least at the supply end, ive come across 4 in past 5 yrs that had live braiding because of crush damage on a 415 volt 5core sy, over 50% of the cable braiding is next to a phase so damaging cable can give a good chance of making braiding live without even touching the earth core. The issue as most will know is if its used as a rough service cable is getting the screening earthed if youve get a 415v trailer on it as it dont all fit in the earth terminal as well as the earth core, so i avoid this use as an extension but do use it as rough service if i can fit the extortionately expensive braiding clamp glands.

Edited extra note! Please remember although it should be earthed the braiding shouldnt be used as an earth conductor, a seperate earth core should be used.

 

[Knobhead]

I know it’s not up to SWA standard but under no circumstance would I leave the braid unearthed. As has been said, it’s all too easy to damage. OK the glands are expensive, but then I’ve never had to pay for them. I just got moaned at for ordering them.

 

[Guitarist]

I personally would always pigtail one end and earth when used as a tough flex. Many electrical engineers didn't bother tho. I have to say that in over 20 years of industrial work, I never came across an issue resulting from the use of this cable. (and before someone tells me that it's not the point I am just telling you my experience).

 

[Darkwood]

I personally would always pigtail one end and earth when used as a tough flex. Many electrical engineers didn't bother tho. I have to say that in over 20 years of industrial work, I never came across an issue resulting from the use of this cable. (and before someone tells me that it's not the point I am just telling you my experience).

Tomorrows only a day away and sods law has an habit of slapping you in the face lol

 

[sysrq]

Again, as darkwood said, it may be designed as a screen but most of the time it is just used as a rough service cabling, like a flexible swa. To provide proper screening it should be connected at one end or both, depending on the frequencies/voltages etc.
RA EMC Awareness - Mitigation - shielding cables is worth a read.

The braid of SY cable is not designed as a screen against EMI as it's made from steel, only copper works as a screen (CY cable). Steel has a too high surface transfer impedance to act as a shield.

http://www.ofcom.org.uk/static/arch...Radiocomms/pages/mittech/design/shieldcab.htm

One end for lower frequencies around 50Hz, both ends for higher frequencies above 5kHz.

 

[t-s]

i always earth one end at least, but i never use the sy glands i just use compression glands and earth sleeve the braid.

 

[amckay]

I use SY a lot at work. The screening just gets cut back and taped up leaving the inner sheath exposed for about 30mm. Pretty much common practice doing it this way

 

[GMES]

Guys the thread is 3 years old so I'm going to close it but feel free to start a new one if you wish to continue with the topic.