Data cable installation in dado trunking - Separating band 1 and band 2 circuits
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- Опубликовано: 31 май 2024
- How can you make data cable installations more reliable? Dado trunking is used extensively in offices and other commercial electrical installations. Why does it have separate compartments? In this video, Joe Robinson explores BS7671 and the requirements for Band i and Band ii cables.
BS7671 covers segregation for safety - but what about screening to reduce interference and improve reliability?
Useful tips for any electricians' installing dado trunking wiring and cable management.
🕐 TIMESTAMPS 🕕
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00:00 Installing data cables in dado trunking
00:35 What's the difference between Band i and Band ii cables?
00:47 BS7671 regulation 528.1 covers Band I and Band II circuits
01:30 How can the circuit be combined in a cable management system?
02:33 528.1 indent iii is the key.
03:14 What about the reliability of data cable installation.
04:34 Adding screening can improve the reliability of data cabling.
05:10 Please share your experience, tips and comments
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🎦 Presented by
Joe Robinson - Technical Editor
#efixx #morepower #bs7671 
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For Cat5e/Cat6 being used for 1G ethernet you won't have an issue in a typical scenario, as the transmission is done using balanced pairs which therefore act to exclude external interference (i.e. no need to use STP, the balanced nature of the twisted pair is sufficient by itself). Something that is genuinely 'analogue' like a stereo audio feed would be far more vulnerable (though even then you can easily deal with it by using shielded cable) - 10G ethernet over copper is a bit more sensitive, but then normally most 10G things done over a distance will be fibre anyway...
Do you need to earth the shielding then?
@@CurvedSlightly A proper cat 6a and 7 termination will inclued a clip on the ethernet connectors. This will be connected to the outer shield of the cable. This will be connected to the earth of the switch or computer if it has one.
Love the video Joe. I just used Shielded cables ran in the top section and ram the mains in the bottom. Never had any issues with either Data or Alarms. Stay safe
Indent v does indeed allow you to install a small conduit inside a larger trunking system. Have done that with a doorbell cable in 4X4 box trunking with a conduit
Very clever with the metal strip tied to the ground.Internet cables have a protective shield against the electromagnetic field, but it is not always enough.👍👍👍
Brilliant video Joe. Adding to this I would also say that this helps to reduce the impact of transients & surges. By using a common routing you reduce the size of any induction loop but by separating and screening them you help to prevent data corruption and damage, line routing and shielding are not really included in BS7671 as ways of mitigating surges but they are included in BSEN 62305 as methods of mitigating risk so this method and product is helping and would be of benefit to the end user.
Thanks very much Sean and thanks for the extra information. 😊
I always run mains in the bottom potion and shielded cat6 in the top and only use the middle when i adding the outlets so they are as far apart as possible for as long as possible
as I have see as huge drops in data when you have to two close together. the steel is great if you need the extra security
Great 👍 advice
now here is a guy who knows his stuff. i am a it guy and i am always ticked off about electricians running utp right next to power. esspecialy if they show it in youtube video's.
I have seen data cable contained within flexible conduit, which itself was installed in steel trunking alongside mains cables.
Not having done compartment trunking for quite a few years now, probably back in the early 17th regs this Is the first time I've seen about using a metal strip, things have changed
Things always do, good to see you keeping up to date with us. 👍
Good informative video
Do you have a video demonstrating the rate of distortion in the data cables? I’ve done a house renovation and added cat 6 cables in some of the rooms. Due to it working in the confines of a typical house structure, I was limited how to run the cables and in one or two locations the data cables have crossed power cables or or run parallel to them. I haven’t switched the data cables on yet but would be interested to know whether all my effort was for naught.
You could physically fit a 16mm trunking inside 25mm trunking and run the band 1 / 2 separate. or put the 16mm trunking in the same chase next to the cable (in a wall chase)
I read we can have low voltage leads inside CUs if it is rated at 300v. So do we really need to have it segregated.
in almost 20 years of separated dado, i've never seen the additional shielding used on any site i've worked on.....we just used a shielded Network cable & never have any issues.
Yeah, I don't know if it's an extra specced thing for government or military buildings etc.
When I was at college doing my HNC in Computer Networking Systems I was always taught the importance of EMI using Cat5(e) (the latest iteration of the cable at the time) and one way which we were taught was to tape up the cable with Silver Tape. To prevent cross talk. Plus we were always strongly recommended not to combine the cable in trunking with power cables.
Sounds like good advice Bryce!
I do recall on one job we used three compartment dado trunking and run the mains in the bottom and the data cables in the top so keeping a greater distance between them ..
Not gonna get many EMC issues with that install!
Thanks for the info Joe. Do the regs have a different approach to UTP and STP ?
Yup, BS 7671 touches on it and BS EN 50174-2 outlines some details on it.
all that really needs to be considered is the potential for a data circuit becoming live. Clearly, each compartment is regarded as a separate system. If you read manufacturer guidance they tell you which compartments to use for each band.
Get a lot less interference anyway if you use twin instead of separate live and neutral like in the video as they will cancel each other's field quite a bit being close together.
When I had my last onsite visit from my NICEIC assessor they mention metallic supports for the cables in this plastic type installation. What's your thoughts on this matter? I appreciate its a question on a tangent from video content.
Yeah if there's a risk of it collapsing prematurely in a fire and entangling a fire-fighter then whack it in. 👍
So if thats the case pretty much all dado installations require it so which then leads me onto the question
Do you know of any dado manufacturers that have metallic supports for their rang as we use MK (others manufacturers available) as they don't seem too. I've just used plastic coated banding strap. I know there is the part in the regulations where if we use a different manufacturer within another then we take the design responsibility for doing so.
do any regs apply to POE+ / POE++ ? or are there any considerations for install?
POE is 48v so is just classed as band 1
The alternative is to use shielded cat5/6/7 cable that said in a budget install that metal plate would be ideal
I had EMI issues at home many years ago although not with trunking. This was much like the couple in Wales with their TV chucking out EMI a few weeks ago. To make it not TL; DR I started to have issues with my ADSL running at a whole 1 meg as was available 15 plus years ago. Had BT out and predictably it was fine on the day they turned up. After a couple of weeks I worked out what was causing it. I had acquired an old computer that I stripped the PSU out of. The router was downstairs at the master socket. When the PSU was switched on it was near the phone line extension to upstairs in the back bedroom. It chucked out so much EMI my interweb went from 1000Kbps to 64Kpbs. Or worse if the PSU had load on it. It was back feeding along the cable pair - I didn't have the 3rd ring wire connected as that isn't needed. As quick as ISDN or even worse! The noise profile was horrific. Suffice to say that PSU went in the bin to silicon hell....
You did well to track that down Michael. 😊
It was a eureka moment. Probably after a couple of bottles of beer....
Never had a single issue with ethernet running parallel to or crossing mains even on big events with 3-phase chucked across a floor, as Alex below said at 1G or even 10G speeds the pairs act as a balanced signal and null out the interference. Is it probably better to isolate - probably, does it in operation make much difference - none that i've experienced. We know the regs like to go a bit past the belt-and-braces sometimes.
Isn't the whole point of twisted pair that common mode induction results in a voltage difference of zero (subject to termination). The twisted pair is terminated with a transformer each end in Ethernet, so the fact that the pair is bouncing around at 50Hz makes no difference to the detector on the secondary winding of the transformer. Non transformer coupled data modes such as RS485 (DMX512 or similar) can be somewhat less tolerant than Ethernet.
Most don't get how ethernet works. A lot think that a 20m cable will have slower speeds then a 30m.
do you have faceplates for the us market
Great video thanks I have never used or installed dado trunking
So this was interesting to watch,.
Off topic if you don't mind, can you please tell me how to use the loop and psc settings on the Robin kts 1620 /kewtech kt62 MFT'S as the new metres have it as two lead high, so I am a bit confused I have my late brother's ROBIN kts 1620 MFT but there is no introduction book
Done a job before for the RAF that specified the trunking using the metallic strips and riveted in place, the pvc trunking back boxes even had a copper lining to the boxes that needed to be earthed. Made a simple job into a pain. Nowhere stocked it and it was all made to order by Schneider
Wow - sounds like a robust installation!
Wow. I can imagine when initial taking on the job thinking, ok simple dado job then all this happens. I done a sound system install in a prison and all the dado trunking was metal and all screwed shut with anti tamper torx screws. Then the decorators chalked it all aswell so was an absolutemission to remove any part of it. Parts got bent and I could find replacement so I had to straighten it all back.
I didn't want to open too much so I used rods and they would get stuck in the dado. I lost a few lengths inside the dado but didn't care as opening the dado to retrieve it wasn't worth it
That's Tempest for you!
Why not using twin and earth for the mains?
T&E not required as the single sheath cores are in containment and therefore protected against damage.
Surely, all the power cables go in the top or bottom tray, then the network cable goes in the opposite? Not just shoved behind?
You've got options!
That would get around and answer my question.. as you'll drop the cable down from the top to the middle section to mount a back box, the cat5e would pass the live etc cables, surely this would create an issue? Or not as they are not running parallel to the other cables?
@@dast_uk If you're using twisted pair CAT5E then you shouldn't get any interference. I think with CAT6 you need to be more careful but you really don't need to be using CAT6 unless you're linking servers or really need the speed in which case you may as well use fibre.
@@efixx The option to do it correctly or not? Yeah, K.
If you Twist you're live and neutral cables together it will almost completely eliminate magnetic coupling between the cables.
Twisting cables together is a very powerful method of reducing interference
I see what you are trying to say but I never saw twisted power lines in normal houses..
I did started to see more and more low voltage pole to pole power lines that were twisted (from local transformers to residentials, 3 phase, 230/400V lines in Y configuration)
I know a particular case where a comercial center used normal paralel lines to the grid and the escalators stairs motors kept burning until they changed the lines from the local transformer to the comercial center with twisted pairs...
To be honest it's not a common technique in the electrical industry but it's absolutely bog standard in electronics and data Communications.
First sign of interference twist your cables together it's that simple.
I just ran STP shielded twisted pairs cat 5e 12 inches away
Sounds good!
@@efixx It might not be; shielded TP has it's own problems with termination and grounding and can easily make 5e less reliable if not done perfectly.
German data installation are big on STP - and are consequently very, very fussy about how it's installed. In 30 years I've _never_ seen it used on a large scale in the UK, UTP all the way and simply maintain a modest separation from AC carrying cables.
I feel like for the amount of cable necessary, you’d be better off putting the mains in the small compartment and the large amounts of data cable in the main.
I wonder how many are really installed to a high standard?
As ever buyer beware!
Use a metal ttrunking
All very well to say , when a customer prefer's aesthetics of plastic.