How will you proceed with this ? Will you have the cable replaced as it’s unsuitable and does not comply with UK standards?

How will you proceed with this ? Will you have the cable replaced as it’s unsuitable and does not comply with UK standards?

is the cable really unsuitable, or just the regime of standards that in the UK means it is not an 'approved' cable type?

the problem usually hinges around the lack of a formal spec for the braid, but if used in places where a non braided flex could be used, i.e  not relying on the braid as CPC or mechanical protection one might argue it is slightly stronger than say arctic flex.

I don't work on lifts, but I do use SY a lot for the EMC advantages it brings.

Mike.

Hi Mike. After reviewing the video from Doncaster Cables, it was noted that the insulation does not meet the standards of BS-approved cables. Consequently, it would be inadvisable to apply a 400V load under these circumstances. What are your thoughts? 

-Andrew

Hi Mike. After reviewing the video from Doncaster Cables, it was noted that the insulation does not meet the standards of BS-approved cables. Consequently, it would be inadvisable to apply a 400V load under these circumstances.

If the insulation is OK for 230V single phase (i.e. one layer of insulation e.g. between core an exposed-conductive-part will withstand 230V), then 400V 3-phase where you'll have 400V across two layers of insulation - approx 200V each - wouldn't be that demanding to my mind.

If it were 400V to earth, that might be different.

   - Andy.

In the Video, Doncaster Cables advises against the use SY as power cables. Do we Stick to manufacturer’s recommendations?

Doncaster Cables advises against the use SY as power cables. Do we Stick to manufacturer’s recommendations?

That video also seemed to say that no-one makes SY in the UK any more ... but Doncaster (according to their web site) only have one manufacturing facility (in Doncaster) - so is their SY UK made or not?

Even their Web page for SY says it's rated for 300/500V, generally meets  BS EN 50525-2-11 (i.e. the standard for mains flexes) and even goes as far as saying  "This cable is also used by electricians in certain fixed installations where only light mechanical stress may occur. " which doesn't feel like an official condemnation.

So still as clear as mud. What's needed is for a proper standard to cover SY (and CY) cables.

   - Andy.

I'm inclined to agree - to set the UK ghosts to rest, although the rest of the continent does not seem so worried,  there probably needs to be a BSI type standard defining the minimum CSA of the copper, the voltage withstand of the insulation core to core and the core to braid, and then the maximum braid resistance per unit length and perhaps for us EMC obsessed types, the braid optical coverage fraction.
In reality I've yet to be delivered any that was unsafe to use or failed on insulation tests.

For a bit of  laugh, as we have the facility, we have from time to time subjected cable samples to gross over-voltages to see the true breakdown behaviour, and it is always many times the test limits - think  high 10s of kV - it is the air spacing at the exposed ends that is the point of breakover in all normal mains connectors.

And yes, that video short is slightly at odds with the written word on their website.

Mike

Voltage rating of wires is an interesting topic. It is typically determined by testing samples over a range of voltages and recording the time to failure. The results are then plotted to determine the long term withstand voltage. A factor of safety, to allow for manufacturing defects and tolerances, is then applied. A piece of typical PVC equipment wire will have a short term withstand of 20kV or more, a long term withstand of around 6kV and a rating of maybe 600V. It’s not a precise science. The minimum insulation thickness is more often determined on mechanical rather than electrical grounds.

This reminds me of that thread I created

BS7671 says refer to MI

engx.theiet.org/.../142399

Mike, you should only use SY,YY,CY cable for control, not power circuits as the insulation is substandard and not to any standard at all