Got a bit of trouble from a customers generator.

* Don't work with generators very often*

Pramac P6000s with a 20A MCB installed. Customer has a perfect generating setup that consists of an external 63 A commando plug, Generating set change over switch (schneider) and a schneider 3 phase DB converted to single phase with RCBOs supplying all final circuits. 

Earthing arrangement is a TNCS with a TT. Both measured correct ZE especially the rod @ 10.4 Ohms.

Plug the generator in and go to do a ZS test and get no earth reading on 2 different sets of megger MFTs.

Try some final circuits which have class 1 socket outlets and again no earth even though the tt is still connected.

Call Pramac and explain, they say put a link in the commando socket that plugs into the generator between N-E. Do this and generator stalls.

Install a temp earth rod to outer casing, still nothing. 

Some of Pramac are telling me that it does not require an earth? The other half of pramac have said i need to put the link between N-E with an earth rod connected to the plug that goes into the Gen? is this correct.

I called the Napit helpline and they have agreed with me that the gen is not safe and get it in writing from the manufactures that this is safe.

Any ideas where I'm going wrong? any suggestions?

Thanks in advance!

Alex