Temporary Earthing/Grounding

Do you have a set of air breaks at the incoming feed to your 11kV sub-station? If so, open the breaks and ensure that the breaks are locked open with multiple lock out tag out devices. Visually ensure that all 3 phase breaks are in fact open.

If you do have air breaks, once you get them open, you will need to bond all 3 incoming local phase conductors (after the air breaks) to each other, and to the neutral (if present), then bond it all to a local ground.

If you do not have air breaks and must depend upon an upstream device that is not under your control, open it, lock it out and install the bonding jumpers to ground at the upstream device then install more bonding and grounding jumpers at the local termination point on your HV stack. This requires a second set of jumpers but ensures no moron upstream can energize the section you are working on. I would go so far as to drop the incoming phase conductors from the stack.

Do not just make up your own sets of bonding and grounding jumpers. Jury rigged clamps have been known to "jump" off a line when energized in error due to the magnetic field produced under fault conditions.

Many firms sell utility grade "clamps" and bonding and grounding jumpers especially made for this purpose. Use them!

Here is a link for you...

http://shop.hilineco.com/index.php/cPath/546_427

Re-read the question, it's the LV side that is the problem, HV earthing is handled by adjacent RMU's.

Back feeds on LV systems is a constant worry.

Agreed... he just needs to open his outgoing over current devices. Those he should have full control of.