Back box size for rj45 network face plate?

I have found some info suggesting that I need at least a 45mm deep back box (to be chopped into brick and plaster) for a network port faceplate.

What I cannot find is what width/height the box should be.

The single port faceplates I am looking at say "fits a 89mm x 89mm" back box. But all of the metal boxes I can find seem to be approx 70mm square.

Is there a special back box needed (I assumed a standard light switch/single socket back box would do).

reg091 said:

I need at least a 45mm deep back box for a network port faceplate.

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That's not true. For example, these MITA back boxes for dado trunking will take data outlets and they are only 25mm depth.

It's more down to what type or brand you are buying. The 'keystone jack' style stick out the back a lot and probably wouldn't fit into a 25mm. Neither would the 'jack-to-jack' style which take a crimped plug in the back and front. The euro module style are much flatter as they have vertical PCBs on the back, so would easily fit into a 25mm box. Branded ones such as Excel or HellermannTyton are a bit chunkier as they are better quality, but they usually come with those bevelled faceplates just to give you a few more millimetres, so would still just fit into a 25mm box, with no slack cable behind. No harm in going a bit deeper than needed though, spare slack cable behind the faceplate is always a good thing.

If you're also putting in HDMI couplers, F connector couplers, etc, then yes, you really should go for the deepest box you dare chisel out of the wall!!

reg091 said:

Is there a special back box needed

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No. Most steel boxes are 76mm square, because that's 3 inches in old money, but the distance between the faceplates screw holes is always the same. The faceplate overlaps the box, just like all your light switches, sockets, etc currently do. Just normal is what you want.

Top man! Thanks for the comprehensive answer.

I think you will find Depth of backbox really depends on the type of network cable you are going to use.

If it's just Cat 5 I don't think you will have any problems, that cable is pretty tough and can handle tight bends, but if using Cat 6 or Cat 6A (even worse). you are limited by the bend radius of the cable. Too shallow a backbox might lead to too tight a bend and it will damage the cables causing a fault or reducing speed. Even 25mm back box on dado trunking with Cat 6A you might have to use an adaptor plate to bring the faceplate forwards of the trunking or socket.

A deep backbox might therefore be required.

Better vendors will tell you the depth needed. For example this Cat 5e Euromod from Connectix required a minimum of 15mm - though it would be "a bit daft" to go that shallow if you could avoid it. These are the ones we standardised on at work (I used to work in a small IT services company), and being nice and shallow would work in sensible backboxes without using ugly "stick out" bevelled faceplates. I'd always try and get the right faceplates to match the rest of the accessories - so where the customer had (say) MK switches and power sockets, I'd use MK Euromod faceplates. I've been accused of being overly fussy about this sort of thing, but it does genuinely improve the aesthetics of a job.