Braiding and earthing SY

[wade88]

Hey guys,

Just a brief one to scout for your opinions. Just been reading several articles about earthing SY. Now i use SY all the time at work, one of my favourite cables because of its durability and flexibility and i have ALWAYS out of habit, braided and earthed both ends of the armour.

Now i have a big job coming up with 15/16 circuits to get done, all in SY. I am on a serious tiem budget to get this done, its a lot of cleating, a lot of terminations and a lot of cable routing and i wouldn't normally suggest trying to cut corners and certainly never when it could compromise the safety of a circuit, but the deeper i dig, the more im reading that most in fact never earth the braid.

What are your opinions on this and what do you all do?

I know you can buy those glands which pick up the pig tail and provide an earth upon glanding but they are £30 a pop and im already strecthed on budget.

 

[Silly Sausage]

I would only ever use the proper gland. (where you split the braid into the slots)
If you're doing that many, you'll be doing them in your sleep in the end!

 

[Deleted member 26818]

My understanding, is that in some instances, earthing the braid at each end can in fact cause problems with data transmission.
Often the braid is only earthed at the supply end.

 

[Darkwood]

SY is originally a control wire with screening so dont call it armour as that is a different thing, it cannot be used as earth but it must be earthed im sick of coming across SY that hasn't had its screening earth when been utilised as power cable, ive also come across on a few occasions now of the SY screening been live due to damage but as its not earthed its just laying there waiting for some unsuspecting person to zapp!.
If you contact the manufacturers of SY some do express and also within their instructions supplied that the cable isn't used as a power cable so in some cases you may contrevene the Regs in doing so but others dont implement this warning. As im aware its due to the fact of the trend of not earthing the braid and i often question the basic common sense of electricians/engineers who premote this practice as it can leave rise to a dangerous situation.
If i recall a few yrs back this discussion was had on here and many openly said they dont earth it but ask the same question now and i doubt any will willingly admit this after reading the potential risk/hazard they create in leaving it unearthed.
You can get SY glands that clamp onto the screen but they aint cheap but it a weigh up on time wasted unwrapping the wire braid and stabbing your fingers with the fine points.

 

[High Tower]

Go on to whiska's web site!, they do dome really impressive Sy glands

 

[Darkwood]

My understanding, is that in some instances, earthing the braid at each end can in fact cause problems with data transmission.
Often the braid is only earthed at the supply end.

This only applies when using the cable for control monitoring or function where eddie currents can form circulating the integral earth and screen tthis in turn can corrupt data or signals, this won't apply to OP's case as i doubt hes wiring a monitoring system on a machine or the likes.

 

[Deleted member 26818]

I have no idea what the OP is wiring.
Data, control or power and lighting.
However the OP is asking how they can reduce costs.
As earthing the braid at only one end, is a common practice with data and control, doing such with power and lighting may help.
As you rightly point out, the braid is in effect only there as a screen, not as a CPC or earthed armour.

 

[44ALLAN]

Wade,
I sometimes use SY as a power cable extension for some of our 'moveable' swaging machines.
32amp 415volt 5pin plugs and sockets on them.
I always seperate and twist together as many strands of the braiding as it will allow to fit in with the cables earth core (and sleeve it) then heatshrink the rest to make it tidy.

You could use a stuffing gland for entry into the panel/junction box then terminate the braiding inside with the earth bar but as has already been stated the correct glands are a bit fiddly but easy to put on mate.

 

[Spoon]

We use a lot of SY cables for power, but we always use SY glands at both ends.

 

[wade88]

The SY will be for power circuits. Inverter panels for motors, condensers, augers. Will be using 6mm SY for the majority of the work. I always earth the braid in the box, after popping through a stuffing gland, i was just curious as to everyone elses practice I will carry on as i always have and earth the screening (not armour my apologies) it only takes ten minutes longer and is worth doing. i wasn't necessarily trying to save money, but be economical on time as that is what i am short of.

Few more late night shifts needed then....sometimes i hate salaries.

Thanks for the responses lads.

 

[wade88]

Second question then, despite having done so much of this cable, does anyone have a better technique for seperating the screening without getting it into a massive tangle and laboriously picking apart the braid stabbing their finger tips as darkwood painfully points out.

I get so frustrated with the stuff especially if it needs to be a long braid to reach the earthing terminal

 

[Deleted member 26818]

I used to use a number needle to pick out the braid, then obviously some earth sleeving and a pin crimp to protect the strands.

 

[Knobhead]

Use the correct gland. You only have a couple of inches of braid to deal with then. Funny how the correct gear saves time.

 

[wade88]

Using the correct gland would cost almost £500 to purchase the quantity i need. If the finances were there to buy them, then brilliant.

 

[Deleted member 26818]

This is exactly why I suggested only earthing at one end.
The braid is an exposed-conductive-part, so should be earthed, but it doesn't necessarily require earthing at both ends.
If the cable is being used in a situation where it could be kicked about or moved around and damaged or corroded, then yes earth at both ends for safety.
However from the description of the work, it appears the cables will not be liable to damage.
Either use the correct glands and only pay out £250.
Or tease out the braid etc. and save your self time.

 

[Knobhead]

Here we go, cost over rules safe practice.

Why did you under price this job in the first place?

 

[Darkwood]

Wade you say its been used for wiring inverters for motors ... in this case you will be bound to EU regs regarding harmonics and rf interference and also manufacturers instructions for the inverter and if the inverter to the motor is SY as it will require screened cable then both ends need grounding down unless otherwise instructed by manufacturer. From experience the screening requirements can vary slightly but usually all give same result.

 

[wade88]

Here we go, cost over rules safe practice.

Why did you under price this job in the first place?

I am not by passing safe practice as already stated i will be earthing both ends of the braid. The safety of the installation will not be compromised, i was simply asking what alternatives were available to me. it was a fairly broad open question.

Thanks Darkwood, I didn't know that, as mentioned prior, i never leave a braid unearthed, i just wanted to know more around the subject from different points of view.

I havent priced this job, it's an in house job that is required to power some new machinery that is being delivered, i am just working on a company budget guideline.

 

[Robotstar5]

Difficult to explain, but if you want a single pigtail ease the braid apart, then while bending the cable into a 'U' shape push a terminal driver round the cable inside the braid then use it to pull the cable out of the braid. The first bits the hardest 'til the cable tarts to slide out, then sleeve & fit a ferrule onto the pigtail.

 

[Guest55]

agree with spins comment earlier.
i'm working with sy flex now , tons of the stuff , all of it used for power rather than signal / control.
earthing the braid is only nessesary at one end IMO , may make life a bit easier for you if youre not using the proper glands.
and im suprised theyre costing you £30 a pack.