efli and rcd test danger

not strictly a DIY question but it follows a debate we were having at work today....

whats people's opinions and experiences of the danger that could arise from these tests, i.e voltages/current appearing on earthed parts.

whats the worst that could happen? is it safe to do so long as you have all bonding in place? and is there a risk of danger, particularly in industrial type installations, i.e lots of exposed metalwork/extraneous parts.

comments welcome, cheers

GN3 states that an efli test should be carried out prior to an RCD test to check the requirements have been met.

My tester will not attempt to carry out an EFLI or RCD test if there is no earth present.

..

I had this argument with an assessor who was supposed to be there to grill me on my procedures. I ended up grilling him...

He insisted that before I carry out an EFLI test that I check MEB's were in place & made sure customers were not attached to anything metallic because of the large currents involved.With my tester, the currents are very low, so this was a red herring.

It is a strange one as you are looking for worst case in a Zs test but need to have MEBs connected to protect from possible shocks when testing so are providing parallel paths which will in theory give a lower reading.
If the MEBs are ever taken out (metallic water pipe replaced with plastic) then the Zs will be higher.I like the method of calculation ( Ze +(R1+R2) ) as with correction factors gives you a more truthful indication of the Zs if the parallel paths should ever change (Unless your Ze is ever likely to change with network alterations)...........aaaarrrgggghhh

Another situation is like in the factory I work in.Where you have several large SWAs feeding bus-panels (.4 x 4core for anyone who's used to imperial sizes) These have no seperate earths ran so rely on the armouring.The SWA is made into the spreader boxes bolted on to the switch panels which is bolted on to an angle iron framework/factory steelwork/lattice of trunking etc so it is nigh on impossible to remove parallel paths albeit the amount of steelwork is so intense that adding/removing trunking/pipework will probably have a negligible effect on the R2 part of the loop.

I'm mumbling now..........