Terminology

[John Rumm]

Yup, for STP to work all the parts of the system need to be shielded.

[Tim Lamb]

I have just varnished the plywood *patch panel* assembly prior to installing the RJ45 connectors. The drain wires will all be available for commoning up and connecting to a nearby ring main earth.

The consensus here is to not bother but I can sleeve them and leave Tim to decide when he tests the system. The .5m patch cables to the switch and the router to switch cable will be unshielded anyway. Data cable has been segregated from mains runs as advised.

As said, this discussion has moved beyond my expected needs:-)

[T i m]

Indeed ... but the question still stands as to what *you* (as you know what you are doing) think we should do with the shield in this scenario?

Drains joined and earthed at the centre of the star (only) and if so to what (water pipe, mains earth, ground spike ...) or just left floating?

Cheers, T i m

[John Rumm]

I really can't see any advantage in having a connection between power circuit earths and your network in this way. Sure you might ground a metal comms cabinet, but not the actual data shielding in the cables. Its not there for electrocution protection but to enhance signal integrity / provide noise immunity.

[John Rumm]

Given this is not a fully screened install, I would just terminate the shield in appropriate fittings where you have them.

You may inadvertently gain a ground path through one or more bits of equipment if/when you take a connection to it with a shielded patch leads.

Within one building on a single phase supply etc its a non issue really. If you were running on catenary wires between buildings, or through an industrial machine shop, then it might be more critical. (and if doing that, in this day and age fibre might be a better bet anyway)

[T i m]

<snip>

OK, thanks. I'll have to ask Tim if there is a facility for the drain wire on any of the faceplates?

'If' and if we have STP faceplates.

(Little chance of) Multiple ground paths?

Understood. Whilst Tim has some of that, none of this cabling is going though any of that, at this time anyway (till I move into one of his outbuildings). ;-)

Cheers, T i m

[T i m]

<snip>

I think the only (very minor) concern / thought was that a floating / unused screen on an STP cable (that might more typically have been a straight UTP) might make matters worse?

If left disconnected it becomes electrically / functionally transparent then there is nothing to have even the slightest concern over.

I'm not thinking it's likely to have any real detrimental effect, just checking what the panel thought, whilst we have the (easy?) option to do something about it.

If on the other hand, having it there and leaving it floating *could* mean noise that might previously only be relevant over a short section (say as the cable passes over a florescent light) is now induced in the whole length of screen ... ?

Cheers T i m

[John Rumm]

Normally if the connection has provision for dealing with a screen at all, then you would fold the foil back over the end of the PVC sheath, and you often loop the wire round the end of the cable form so that it makes connection with the screen of the plug / cable grip etc. (much like you would deal with the braid in a CT100 co-ax)

With some RJ45 plugs there can be an advantage to looping the wire round two of the pairs such that you can be sure it gets pushed well up into the plug since the screened bit of the plug does not always connect that well to the cable sheath.

[Jim K..]

Have you packed your suitcase yet?

[Jim K..]

Depends how long it takes him.... ;-)