Sorry aggie,
I only tried to be a bit funy in the previous reply..
The mass of your stainless steel cabling is insignificant compared with the mass of your galvanised posts. This means that the small area of contact won't generate any significant corrosion problems, as it would with galvanised wiring attached to stainless steel posts. I suggest first to use a decent paint on the posts, on the area of contact and if possible use some isolating plastic to clamp the cabling onto the posts. Also, of possible, try to prevent the contact of the screws/bolts with the SS cabling.
Now, back to the question, do you have a fire extinguisher?
cheers,
gr2vessels