Many bore hole submersibles are suspended on polythene pipe, with a back-up of a safety rope attaching the pump to the bore cap to prevent loss in the event of poly pipe failure. I have, over the years, retrieved quite a few pumps with only the safety rope bringing it back.
The customary safety rope today is a stainless steel cable, although occasionally there have been polythene ropes used.
The poly rope is relatively risky due to its life span limitation, difficulty in tying to avoid slippage and relatively easy to damage by abrasion.
Stainless steel is fine but often we find the cable clamps (normally two at each end) installed incorrectly; or one each way in an effort that at least one of the two will be right. The correct way is with the saddle on the live side of the cable and the U-bolt over the short end – never saddle a dead horse is the rule to go by.
Some folk uses swages instead of rope clamps. Swages are certainly very good but prevent re-use of the rope without having to shorten it.
In every case, there should be an eye installed to prevent the rope crushing or crimping. Nit often seen on installations but important just the same.
There are some things to be always remembered:
- there is an electric supply going down the hole
- Ensure that electric cable and the safety cable are securely kept away from each other during installation.
- Always first check that there is not ‘live’ metal bore cap, especially on a bore cased with PVC pipe (an insulator) when servicing a bore pump
- A metal safety rope is a very good conductor, much better than bore water
We do not use poly pipe rising mains or safety ropes – see article on Rising Mains.