Personally, I chose to make a brick arch which is between a single story part of the house and a wall which is attached to the garage, but that was overkill. In essence, it replaced a wooden beam which had supported galvanized conduit. 4 x 2 properly treated should be fine.

I contemplated going down and up, but the ground is concreted.

Mrs P and I are short, but the centre of the arch is 2.0 m high. Quite why it should be any higher over a pedestrian walkway is beyond me. Put another way, would you have any qualms about installing a cable above a garage door?

AFAIK, The height requirement over a pedestrian walkway was firstly to allow for people carrying ladders or long lengths of building materials, and secondly to place it out of easy jumping range from children who might otherwise climb upon or swing from the cable.

Even so, there are plenty of examples that do not meet that guidance but are fine in places that ladders will not be carried etc. (between adjacent farm buildngs side by side accross a gap not on the way to anywhere in particular comes to mind) . The key is to perform an assessment of the individual situaion.

A cateneray wire might not be a bad idea if the mounting involves awkward angles - 16mm SWA will not want to be sharply flexed, - its not really a matter of strength but more one of speed to install and managing stress on the cable. Catenary eyes etc are not that expensive. Do not forget that it will droop - it takes an infinite tension to hold a wire horizontal, and a drop of 1/10 to  1/20 or so of the span at the low point  is a far more realistic target and will not pull the wall anchors out or the top brick off the row ;-)

I'm sure it is obvious but bring the cable indoors into the dry at both ends to join it,and via some sort of drip loop, so water cannot run along the cable and downwards and in.

Overhead wire is quite fun when you get used to it - my baptism of fire was a Scout Jamboree for 15000 odd scours with several km of festoon lights and 3 phase dstro between vertical  scaffolding poles. There we used the saddle clam style of scaff clamp and lay the cables in the up turned palm - very few building to buliding situations are that easy.

Miike.

I installed a power cable and also several ELV data cables between nearby farm buildings, at less than the recommended height, this I felt to be safe as the cables were threaded through a length of steel scaffold tubing. Almost indestructible!

One 3 core 6mm SWA, one cat 5 cable and one 7 core mains rated flex used for various elv signals..

Thanks all for the responses.

Its over a passage way between garage and house, having seen it today only about 1m wide.

House is constructed with concreate slabs hung on the outside, which is going to make life interesting with drilling,

I think I am going to stick with a strong support between the buildings at about 2.7 meters (height of the garage, with the support just below the holes to create a drip loop.

The scaffold bar gave me an idea that galvanised hand rail would provide a good support and would be relatively easy to secure on to the walls. 

16mm SWA is going to be quite weighty, even over a short span, so yes, something like a scaffold pipe or handrail pipe would be good if it can be secured sturdily at each end.

I think the regs book dimensions stemmed originally from the risk of contact with bare live overhead conductors back in the day.

Yes, but they need to be at no less than 5.2 m. The table is nonsense. As I have said earlier, what is the difference between a passageway and a doorway?

House is constructed with concreate slabs hung on the outside

"Airey house" or something similar? (I remember many of those from my youth). I suspect there may be a steel frame to contend with as well as the pre-cast reinforced concrete (which might not like drilling) and I've a vague feeling that asbestos was part of some of the prefab designs of that era too.  In the old days cables would often be routed outside via a door or window frame rather than through the wall - there might be a thought there.

    - Andy.

Chris Pearson said:

As I have said earlier, what is the difference between a passageway and a doorway?

Most people woldn't try to carry a 10 foot ladder through a 6'6" doorway without lowering it first.