In message , bert ]
writes

Thanks for all the comments and suggestions. Will talk to the chap who
wants to set them up tomorrow. They're to illuminate a sheep dog
training ring so we can carry on training through the winter evenings.

I would also go for scaffolding tube or if you have the money, proper
lampposts.

Telegraph poles need proper planting to be secure, you've seen the BIG
augers on the back of tractors, or BT/Openreach installation vehicles?
It's not just a case of digging a hole and dropping it in. They are
also blooming heavy!!
Lampposts are slightly easier, but still require a hole and a bit of
concrete. Also rather heavy.

Will you have machinery on site, or is it all to be done by hand?

Scaffold tube would be quick and easy, also more easily moved if you
wanted to re-arrange the layout. A very quick fix would be a length of
tube knocked into the ground, I use putlogs which are designed to go
into the gaps between bricks when building (so I am told, I have never
used them for that) A large sledge hammer is most useful here, and
someone who can swing it! The ones I use are about 5' long, 3' below
ground and 2' above.

http://www.semvuatrading.com/uploads...684_putlogtube
end.jpg

2 of these with a gap between them for your main pole and a pivot would
be simple enough. You could then pivot them down for maintenance. If
you were sure of the locations then possibly one short pole concreted
into the ground and a couple of swivel clamps.

I use them, with just one putlog, for temporary loudspeaker
installations on grass, but only with 3m poles and only for a week or so
at a time. They remain remarkably firm. i.e. "can be a bugger to pull
out at the end of an event!

Have you sorted out an electrician, a supply point and cable suitable
for the job too?

--
Bill
( A different one )