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Topic Title: cable type??, steel braid, what type pls
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Created On: 26 May 2008 04:41 PM
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 26 May 2008 04:41 PM
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Grandfortune

Posts: 348
Joined: 10 April 2007

hi all,
after a type of cable, its has a steel braid around it likr aurmoured cable and a see though pvc sleeve over it, seen it alot in industrial places feed machines, a builder has loads of it and asked if he could use it to feed an out building,in a trench like laying aurmoured, i wasnt sure as i dont like the ound of it, any ideas if i can use it,cheers
 26 May 2008 04:45 PM
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John Peckham

Posts: 7381
Joined: 23 April 2005

It is SY cable. Some makes/types are suitable for use outdoors and some are not. I have not seen it used buried in the ground and I don't think it is suitable for this use at any depth.

John Peckham

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 26 May 2008 05:29 PM
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Jaymack

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This SY cable is suitable for control and signalling cable for machine tools, assembly lines and general plant as a flexible cable, between fixed and mobile equipment e.g. umbilical flexible cables. It has a bright annealed galvanised steel wire braid for mechanical protection. It has a clear outer PVC sheath. There are special glands available to capture the braiding. It is certainly not suitable for below ground.

Regards
 26 May 2008 07:41 PM
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Grandfortune

Posts: 348
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thanks guys,though it wouldn't be good for outside
 26 May 2008 07:47 PM
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deleted_2_tony30

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Originally posted by: Jaymack

It is certainly not suitable for below ground.



Regards



Jaymack, would be grateful if you could point me in the direction of the reg for this?

Regards

Tony
 26 May 2008 07:58 PM
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perspicacious

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"Jaymack, would be grateful if you could point me in the direction of the reg for this?"

Tony

You could start with 512-06-01 and go onto 522-08-01 and ask the designer about 511-01-02

Regards

BOD
 26 May 2008 08:23 PM
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Jaymack

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Originally posted by: tony30

Originally posted by: Jaymack
It is certainly not suitable for below ground.

Jaymack, would be grateful if you could point me in the direction of the reg for this?


Does this mean you have some waterlogged stuff buried?
Why would you find a specific regulation applicable to this cable in the regulations? - assuming that you mean BS7671. See BS8500 and VDE0250.

Regards
 26 May 2008 08:59 PM
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deleted_2_tony30

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thanks for that guys, i will follow that up at work tuesday am.

I dont know since having a sprog, i seem to forget more electrical facts, but know every cartoon character by name now.

Cheers for the replies.

Tony
 27 May 2008 01:43 PM
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deleted_2_tony30

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Jaymack,

Looked at 512 06 01 , so if the cable was installed in a duct this would seem to conform
522 08 01 - if cables are properly pulled into ducts with sufficient space factor allowed this could be ok, worst case since duct for single cable
511 01 02- thats the hard one depending how you look at it
all the risks of the environment in where the equipment is to be operated needs to be considered, so open to interpretation
BS8500 appears to be a spec for concrete, possibly a wrong number somewhere
vde 0250- cant find info on that
looked at bs 7540,7540-2,5467,6500 but need a bit of time to digest them.

Regards

Tony
 27 May 2008 01:55 PM
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AJJewsbury

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Some manufacturer's data sheets for SY (e.g. http://www.batt.co.uk/images/pics/7790sy.pdf ) carry the statement "SY cables are not suitable for direct connection to the public mains supply" - I'm note sure what they mean by 'direct' but I'm guessing that they mean the use for sub-mains or simple final circuits is out.
- Andy.
 27 May 2008 02:55 PM
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Jaymack

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Originally posted by: tony30
Jaymack,
BS8500 appears to be a spec for concrete, possibly a wrong number somewhere

Apologies it is BS 6500.
Apart from that, is there a specific application that you have in mind, or is this an academic exercise? Why would you wish to install this flexible control cable underground?

Regards
 27 May 2008 03:02 PM
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Jason1958

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Whilst SY looks like armoured, it is not.
- SY has 80% optical metal coverage
- SWA has 90% optical metal coverage
- BS8436 has 100% optical metal coverage

SY is aimed at HVAC *flexible cord drops* where it is favoured over flexible conduit. Key attributes are "handling tough", high flexibility, fast install, high IP rating via glands, vibration tolerant compared to flexible conduit. The glands are about 4-6x the price of SWA CW, be prepared.

Example.
Garden centre climate control in aluminium frame buildings, uses automatic vent openers & variable speed ceiling fans. At certain fan speeds the vibration excites weak noggin/purlins into resonate that splits flexible conduit. Wired in SY the problem was resolved, at least for now.


The only way you could use SY (or FTE, 6491X etc) would be to use twinwall electrical ducting at depth "suitable for the grounds intended use" (and limited by cable/duct protection, no real armouring). After paying for the ducting, SY glands, you might as well have just used SWA. That is *IF* the SY cable manufacturer says it is suitable for continuous immersion in water, because SWA is and I bet SY is not. SWA is not suitable for submarine use, ie, across a lake, so there goes your secret bunker away from the wife.

Most common mistake with SY is to use it for extension leads as "flexible, looks armoured" and either cut the armour off or try to extend it into a plug. Neither of which are acceptable.
 27 May 2008 03:48 PM
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perspicacious

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"That is *IF* the SY cable manufacturer says it is suitable for continuous immersion in water, because SWA is and I bet SY is not. SWA is not suitable for submarine use, ie, across a lake,"

This appears to say SWA is suitable for continuous immersion in water but not if this water is in a lake

Regards

BOD
 27 May 2008 04:27 PM
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OMS

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Extracted from BS 5467:

Q.3.5
Cables specified in this British Standard are not specifically designed for use:
a) as self-supporting aerial cables;
b) as submarine cable or for laying in water-logged conditions;
c) where subsidence is likely, unless special precautions are taken to minimize damage;
d) where any exposure to excessive heat is involved;
e) where the oversheath is subjected to a voltage test after installation.


Note Point b.

Debateable if armoured cable is actually designed for use in permanent wet conditions

Regards

OMS

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Failure is always an option
 27 May 2008 09:14 PM
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Jason1958

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> This appears to say SWA is suitable for
> continuous immersion in water but not
> if this water is in a lake

I chose my wording & example carefully :-)

Laying SWA in clay will result in the cable effectively continually immersed in water.
- The minimum 150mm sand overfill, soil, will be water permeable
- The clay layer beneath the cable is not water permeable

That not withstanding, SWA is not suitable for submarine applications - ie, in an actual "lake".


> Note Point b.
> Debateable if armoured cable is actually designed for use in permanent wet conditions

Well if not, we better have another power cut, people better start digging & figure out what IS suitable for Direct Burial. Probably the spark suggesting otherwise :-)

A large part of the UK subsoil is clay.
Those in the south of course dig in chalk and drink water that has been flushed a few days earlier :-)
 28 May 2008 03:31 PM
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OMS

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Well if not, we better have another power cut, people better start digging & figure out what IS suitable for Direct Burial. Probably the spark suggesting otherwise :-)


Well for stsrters I would consider an MDPE oversheath as opposes to PVC or LSF.

The standard does allow discussion between the purchaser and the cable manufacturer if permanently waterlogged conditions are expected so MDPE oversheath would be allowable in the cable standard if agreed to by the manufacturer

Regards

OMS

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 28 May 2008 04:57 PM
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Jason1958

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"Consider" granted, however a quick call around...
- PVC/LSOH sheathed SWA is fine for direct burial in waterlogged clay soil (CPC AEI Prysmian)
- MDPE should be considered if running across the bottom of a lake (example cited by AEI & Prysmian)

SWA LSOH did have issues about 20yrs ago with waterlogged clay, there are no issues now (cited by AEI).
 28 May 2008 05:26 PM
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OMS

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Well as i said, the standard refers to not specifically designed for etc etc

Clearly, your selected manufacturers have confirmned its use in waterlogged conditions (verbally I assume as opposed to in writing) so as a designer you could claim to have the assurance of the manufacturer that thier cable exceeds the requirements of a standard.

I think the point I was trying to make is that SWA does not need to meet the requirements necessary for its use in water so the assumption that is is OK shouldn't be made without checking the manufacturers data.

Although I would be interested to see if the manufacturers will give any written performance warranties if called upon to do so regarding use in waterlogged conditions.

SWA LSOH did have issues about 20yrs ago with waterlogged clay, there are no issues now (cited by AEI).


What changed then I wonder

Regards

OMS

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Failure is always an option
 28 May 2008 06:40 PM
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intrinsic4225B

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I think I recall at one time cables sheathed with polychloroprene (PCP) being offered for submerged use.
 01 May 2013 10:43 AM
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den1962

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I seen Sy used from a pv inverter, to 63a isolator and the braiding not unearthed even tho they have correct glands used, just tape up inside.
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