Data cables in electrical control panels

If it's data cabling (of any kind), BS 6701 (as referred to by BS 7671 for telecomms cables) requires at least 50 mm physical separation from LV power cables, even if the cables have metallic armour or screen, and even if the cables are in metallic containment.

That would appear to preclude the use of cables like EV Ultra where the internal "cat 5" is used as a data cable (e.g. Ethernet, EIA/RS 485 etc.)

EV Ultra cable also has the issue that SY, CY and YY has - no constructional standard, so evidence of "at least as safe" and suitable declarations to be made, see Section 511 of BS 7671.

Hi, 

Are you saying that EV Ultra cable is therefore not allowed? The product itself is CE certified and it’s being installed everywhere. 

With regards to control panels, 50mm makes sense but this rarely happens. I’ve seen big corporates build panels with VSDs that are all linked with data cable that shares the same containment as mains (cables touching). There are also tones of products on the market which have LAN/other ports mounted directly next to a mains connection, so a 50mm spacing is impossible. 

I suppose it comes down to common sense at the end of the day and ensuring the solution works. 

In practice the 50mm rule is a bit arbitrary and only really  makes sense in terms of avoiding EMC problems over long distances (metres of parallel runs). You can come a lot closer if the region is only short, but by how much and what else needs doing is highly specific to the situation. If in doubt earthed screens allow things to touch opposite sides of the screen and not see each other under most circumstances . Basically the design authority needs to be able to work out what is going to happen EMC wise. Inside the box the external wiring standards are not really applicable, but the geometry is understood, by someone at least. Voltage related spacing  is the really easy part of the question as insulation to hold off mains is less than 1mm of PVC. Understanding the nuances of EM takes half a lifetime ;-)
Mike.

Reading about EV Ultra cable it actually says on the CEF website the Cat 6A is for the connection of a CT, it doesn't actually mention using it for an internet connection.

• EV ProInstall Cat6A LSZH Cable is for EV charging unit power and flow monitoring
• The cable is a combination of power cores and screened Cat6A data cable offering a solution for quick installation including connection to CTs, eliminating the need to run two separate cables

EV ProInstall 5 Core CAT6A LSZH Cable Black (Cut Length Sold By The Mtr) ( E1A050060UCAT6 ) | CEF

Page four:

EV-Ultra_Cat5e_Datasheet.pdf (doncastercables.com)

Hi, 

Thanks for your answer. 

These cables are designed for DMX and audio. 

https://linkitaly.com/products/power-audio-dmx-hybrid-cables/

There are also lots of light fixtures on the market with hybrid power and data cables (DMX over twisted pair). 

I am sure that this is then covered by a product standard. BS7671 outlines installations, and instructs to follow manufactures guidelines. If a hybrid cable can carry data in line with specification in this format, the installation is then complaint. 

That’s my view at least. 

Hi Mike,

Makes sense. Thanks for your answer.

As for perfect planning I’ve seen data cables whacked into control panels, twisted around mains cables like spaghetti, working flawlessly for years. Whenever I design systems like this, I try and ensure data and power are kept apart as much as possible. 

When you have a LAN port 10mm away from a mains connection on a product, this is somewhat difficult ;-) 

Thanks. 

That is what Doncaster Cables say in the EV Ultra datasheet.

mapj1 said:

In practice the 50mm rule is a bit arbitrary and only really  makes sense in terms of avoiding EMC problems over long distances (metres of parallel runs).

This is NOTHING to do with EMC.With EMC in BS 50174-2, there are conditions for zero separation.,

This 50m min, however, is listed as a fundamental safety requirement in BS 6701.

Only quotes BS 7671, and doesn't consider BS 6701 (which is referenced from BS 7671 )