Lightning Protection Noise on earth rod

[sparky1690]

just been spammed with testing an installations Lightning protection system out in Afghan. was installed nearly a year agbo but the lad that installed it has now done one so i get the honour of testing it.

it has two sets of cabins each with 8 earth pits around them, the rods are not linked below ground, some of which are inaccessible now because of walkways etc.

i only have a fluke clamp meter as my megger is away for calibration so getting in to the pits to try & test is a no starter.

when i measure the down tapes i am getting the noise symbol on the test meter & when refered to the instructions makes the result void. this does not happen at every down tape only around half of them. the others pass but only just, around 9 ohms.

any ideas on how i could rectify the problem short of digging trenches & ensuring they get some sort of farraday cage type effect.

cheers.

 

[olly w]

I would start by checking all the connections above ground for corrosion and tightness, and hope to find something.
I've only used the clamp on meters a few times, but I have found when testing indvidual spikes with a standard meter it's pays to use the rest of the installation as your test electrodes, that way poor connections above ground show up.

 

[sparky1690]

cheers olly, had already done that.

guess i will have to wit for the Megger earth Tester to get back from calibartion & see what it comes up with.

thanks.

 

[olly w]

Is the lightning protection connected to the main earthing terminal or seperate?
Is it possible to isolate the power to the cabins, and then try?
I'm guessing it's all generators out there, if so are they close to the installation?