Ethernet in conduit

thenewoc · 7 Sep 2013 at 12:31

Hi,

As some of you may know I've been working on a home cabling project recently. I've been converting a sort of airing cupboard (no tank) to be a network closet and putting pattress boxes in where I need to get cabling to. I have now gathered almost all the components such as cable, conduit, face plates etc but as yet no conduit boxes.

When I was researching some electrical info on putting sockets into the cupboard I came across someone else's post (different forum) regarding inspection bends / conduit boxes being required between 180 degrees worth of conduit bends. Does anyone here know where that originates from as I can't find anything through Google. Is this a standard for conduit installation and does it apply equally to ethernet / low voltage as it does to electrical cables?

bremen1874 · 7 Sep 2013 at 17:19

You can do more-or-less what you want with data cabling as long as you keep to the recommended minimum bend radius.

As far as I know the suggested use of conduit inspection bends is just to allow the cables to be pulled more easily.

Why are you using conduit? Even 25mm won't take many cables, and it'll get very difficult if you try and get it anyway near full. Trunking is a much easier option.

thenewoc · 7 Sep 2013 at 18:19

I've probably become a bit confused as to whether Ethernet was considered low voltage cabling and thus I think in or out of BS7671 scope. If it were in scope then there would be I believe an additional headache of providing fire barriers for conduit above 32mm.

http://www.tlc-direct.co.uk/Book/4.5.2.htm

As I need to go from top loft bedroom to various parts of the house, flexible conduit seemed a good choice, albeit the diameter isn't great. I intend to run separate conduit runs to each room with each carrying aprox. 4 cables. 4 cables seem to take up about half of a 25mm conduit. Rooms that need more than 4 cables will have 2 conduit runs, such as bedrooms with flat screen TV and 4 port separate PC faceplate. The beginning of the conduit runs after leaving the network closet via the ceiling into the loft then proceed to drop down the boxed in soil pipe enclosure. The conduit I can clip going into and out of the vertical drop. If I used large trunking I wouldn't need it to be large for the full journey from A to B so would have to then find ways to join in smaller sections branching off. I think the conduit provides a neat enclosed solution from end to end.

I'm unsure of minimum bend radius at the moment but I have the following cable.

http://www.blackbox.co.uk/gb-gb/fi/1235/13221/GigaTrue-550-CAT6,550MHz-LSZH-Bulk-Cable/

I'm hoping I can go near 90 degrees for the bends I shall need to do.

Scream · 16 Sep 2013 at 14:27

90 Degree bends are not a problem as long as you have a nice 'round' bend if you know what I mean and not a sharp bend.. When you make the bend, you don't want lots of wrinkles in the outer sheath and if that happen's, you know you are making the bend too sharp.

For conduit, just get a bending spring for the size of conduit you are using and make your own bends and also pull all the cable together to make it a hell of a lot easier.

thenewoc · 19 Sep 2013 at 17:15

Scream said:
90 Degree bends are not a problem as long as you have a nice 'round' bend if you know what I mean and not a sharp bend.. When you make the bend, you don't want lots of wrinkles in the outer sheath and if that happen's, you know you are making the bend too sharp.

For conduit, just get a bending spring for the size of conduit you are using and make your own bends and also pull all the cable together to make it a hell of a lot easier.

Thanks for this, I think I understand it better now, I was struggling to get my head around the terminology of what they were trying to convey.

The box states "Maintain the proper bend radius. Do not kink or bend the cable more than four times its diameter.". The diameter of the cable is just 6mm so I take from the above statement that I must not have a bend radius less than 24mm? That seems quite low but if I've understood this right a low maximum bend radius would be a good thing as I'd be unlikely to come close to it. Having experimented with a piece of cable going through a standard conduit terminal box the worst case scenario of the cable taking a route where the cable was on the sides closest to each other around a 2 way right angled terminal box would see a bend radius of around 25mm.

Here's a link for anyone else that might be a bit confused by the term bend radius.
http://www.had2know.com/technology/minimum-bending-radius-factors.html

As far as the conduit is concerned I'm glad to say I don't need to do any conduit bending as I'm using corrugated flexible conduit.