Cable Bending Radius: Don't make this mistake

Maintaining the bending radius of a cable during and after installation is a critical criterion for safety and performance. This video looks at the bending radius of power, data and fibre optic cables. We also explore the features included in Marshall Tufflex dado trunking which help electricians when installing cables.
Learn more about the Marshall Tufflex Stirling Dado trunking used in this video.
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[@efixx]

Learn more about the Marshall Tufflex Stirling Dado trunking used in this video. 👉 kzbin.info/www/bejne/aWSQlKynmsaBpLc

[@brianwood5220]

Well explained Joe, especially those Fibre Optic Cables. We are all more likely to come across them on a regular basis these days, especially with the advent of FTTP. The reliability of this system is far superior, so it needs to be installed correctly if it's going to last. Thanks for sharing.

[@guffermeister]

CAT6 cables have a solid core to prevent you from bending it too much. The conductors in the cable pairs in CAT6 are also slightly thicker than in CAT5 and earleir to cope with the increased data flow to maintain the signal integrity. The reason for the bend limitation is that the CAT6 data cable standard (and later) is very anal that the 4 internal cable core pairs are very close to each other in length (as in mm) after installation. It's why CAT 6 specific RJ45 connectors exist to keep those cable lengths the same in the plug. The same for patch panels - the lengh of the tracks from the IDC punchdown to the pins in the socket are all the same length - if you can see the PCB it's mounted on you'll likely see extra length on some of the tracks. They are like this in the earlier standards but not as stringent with the length tolerance. If you don't you end up with mismatched timings as the data runs at many MHz of frequency. All to do with timings and propergation delays....

[@MrJR86]

Sorry it is a few more parameters when it comes to cat5/6/6a/7: Wiremap. Length. DC Loop Resistance. Signal (Propagation) Delay. Attenuation - Insertion Loss. Near End Cross Talk - NEXT. Attenuation to Crosstalk Ratio (ACR). Power Sum NEXT (PSNEXT). Return Loss. Far End Crosstalk (FEXT). Equal Level Far End Crosstalk (ELFEXT). Power Sum Equal Level Crosstalk (PSELFEXT). Alien Crosstalk - AXT. So tight bends cause internal reflections and Crosstalk thereby fail certified tests.

[@MrJR86]

Also the length from par to par within the cable will vary, due to the fact each par has a different rate of twisting.

[@guffermeister]

Was trying to keep it within the realm of a sparkie :D

[@mfx1]

You have spoken a whole heap of rubbish there!

[@Dog-whisperer7494]

I don’t install data cables never had to, but this was most definitely an interesting topic something to remember for possible future use. Thank you Joe for a fantastic video as always 👍

[@efixx]

Could be a new mission for you Sean

[@Dog-whisperer7494]

@@efixx maybe

[@kjomen]

Here in Norway we use a cable designed to be installed open on the walls and ceilings (protected only by laying next to skirting board) This cable is approved with a bending radius of 2x cable diameter for up to 90° bend (4x for >90°) It looks kind of similar to your twin&earth cable

[@efixx]

Can you send us a link for our curiosity

[@ecoworrier]

I remember going to a high street computer shop in London and buying 10m of loose data cable and the guy folded it and scrunched it up before giving it to me. "What is the bend radius of that cable"? I asked. "I'm not sure" he said. "Then you better cut me a new cable then..." 🤣

[@efixx]

Oh dear... 😂

[@mfx1]

Maybe sparks should just leave data cables to people that know what they're doing just like sparks complain about other trades doing electrical work. Fibre bend radius for installed cable isn't so much due to fragility, it would have to be quite an extreme radius for that but more about how light refracts passing through the cable, tighter bends cause higher attenuation although the bend radius for pulling cable IS more about strength and preventing micro cracks from forming.

[@edbouhl3100]

Any suggestions on how to transition cat6 going through and then up a wall ( a 90 degree turn)? Are there any conduit LB fittings that would work? Thanks for any thoughts.

[@gnlgrim2]

Always love your videos guy, but not one sparky on site measures, calculates and draws a mock up bending radius as a example for his apprentices :). it gets installed and if the bends looks neat, job well done. lol

[@efixx]

😂 I know, it's just interesting to have a visual reference in the video. 👍

[@FirstDan2000]

How well does a Conduit Box rule of thumb work? Would be interesting to see a video showing this.

[@sosocute3078]

Thanks for the video sir. Very helpful, yet, how is the bending radius can be calculated for the thin slends within the optical fiber?

[@lawrencer25]

Fabulous video. Thank you 🥳🥂🕺🏽

[@jonathanbuzzard1376]

Most decent Cat6a has a bend radius of 15mm. I don't know where you are getting your fibre optic cable from but in 2022 bend insensitive fibre is the norm and you can wrap a patch lead tight around a pencil and it will still function just fine. Finally, you mention Cat7a; arggggggh Cat7 and later is not suitable for use period. It is a bunch of 4 miniature twinax cables that need special connectors to avoid near and far end reflections and *NOTHING* whatsoever is available to purchase with the appropriate sockets. Further no IEEE 802.3 standard allows for the use of anything higher than Cat6a for structured wiring, aka permanent installation. There is a standard for Cat8 for 40Gbps Ethernet as point to point in the data centre, but I repeat there is *NO* equipment you can buy that actually uses the standard and it's only for point to point patch leads anyway.

[@efixx]

Cool!

[@piotrlobacz]

I can't ever get pvc condu to bend niceley in accordance with regs.

[@therealdojj]

I've just run my data cables around the house over Christmas and I didn't bend them around anything that small 😯 I think my loop was 100mm max at the smallest and 300mm at the largest I find out the hard way not to kink the cable as I only found out it was broken when I'd hooked out so up and was testing it 🤦

[@efixx]

Top work, should have a data installation for life there! 😁

[@therealdojj]

@@efixx I read glad that I guessed correctly and don't need to rip it so out again, I'd need to move a couple of wardrobes 🤣

[@guffermeister]

Over short lengths you can get away with it. Get to the 60 or 100 Metre specification length (depending on the throughput you want to support) and it becomes critical

[@efixx]

Phew! 😅😂

[@CarlosArruda77]

Minimum bending radius? I believe you meant to say maximum bending radius?

[@davesharp7315]

And then bend-insensitive fibre turns up 🤣