Earth rod

[Carlosfandango]

This might sound like a daft question to some of you guys. I've never had to work with TT systems before and I'm wondering how you go about getting a spike into rocky ground? The job I've been to look at has a spike in just now but the Ze at the mains is 107 ohms. I need to get this to an acceptable reading. I'm led to believe the area is build on bedrock! Any advice?

 

[Engineer54]

If this holiday site now consists of 17 chalets, then you're best bet is to advise the owners to contact the DNO to find out if a PME/TNC-S connection is available on the supplying distribution network.

Whatever way you look at this site it's gonna fail big time, with no additional RCD protection in place. Sounds to me like the owners have had a bunch of cowboys in, to hook up these chalets to the sites distribution system. Just complete your full report and hand it over to the owners.

If they are daft enough to have rented out these chalets to the general public with an unsafe electrical supply/system that doesn't comply with BS7671, then they are just asking for a S**t load of trouble to fall on them, from a very great height....

 

[dazza1981]

This sounds like a lovely job to me tbh....... do your report on each chalet and hopefully you will get the remedial work and be quids in.
I certainly would not be contemplating walking away from this job but infact rubbing my hands at the prospect of a nice little earner!!!

 

[GLENNSPARK]

Could put a rod in at each chalet so that you create a fairly widespread web of connected rods.

yeah...

thats what it needs....

 

[Knobhead]

There’s one thing I noted in this thread, the OP doesn’t think 107Ω is good enough. Can’t fault that.

How deep can you get before hitting rock? If you can get down a couple of foot then a tape lattice or a tape circumference ring around the property will once the ground has consolidated give a good reading.

Other than that its drill as deep as you can and install multiple rods to form a nest. The holes need filling with Bentonite concrete or similar, before the rods are driven in.

As Dave said a rod at each chalet will give a wide spread nest.

 

[GLENNSPARK]

There’s one thing I noted in this thread, the OP doesn’t think 107Ω is good enough. Can’t fault that.

How deep can you get before hitting rock? If you can get down a couple of foot then a tape lattice or a tape circumference ring around the property will once the ground has consolidated give a good reading.

Other than that its drill as deep as you can and install multiple rods to form a nest. The holes need filling with Bentonite concrete or similar, before the rods are driven in.

As Dave said a rod at each chalet will give a wide spread nest.

agreed Tony.

Its all suggestions i`v already made.....

if depth isn`t an option then the only other ways are parrallel paths and contact area......

 

[Knobhead]

Some of you will know Victoria Centre in Nottingham. I was on a course with the then EMEB. We were talking about earthing for MV systems, they had major problems getting <1Ω on the Bunter sandstone strata. They had to drill down 100’ to get decent readings. The boreholes were filled with urea gel.

 

[Engineer54]

They would have been better using Marconite to fill the bores.... There's nothing better on the market, and it won't dissipate or wash away over time.

 

[old_sparky_RE]

Here you go Shanky from BS 7430 section 10.2 ....

A number of rods or pipes may be connected in parallel and the resistance is then practicallyproportional to the reciprocal of the number employed so long as each is situated outside theresistance area of any other. In practice this is often assumed to be satisfied by a mutual separation equal to the driven depth. Little is to be gained by separation beyond twice the driven depth.
So 1.8 it is then.​

 

[Guest111]

I have stayed it these types of chalets several times and they all seem to be individually staked just outside each cabin.,sad isn't it when you go on holiday and end up checking out the electrics where you're staying.

 

[Silly Sausage]

I have stayed it these types of chalets several times and they all seem to be individually staked just outside each cabin.,sad isn't it when you go on holiday and end up checking out the electrics where you're staying.

My test gear is one of the first things that gets packed!

 

[dazza1981]

My test gear is one of the first things that gets packed!

Bugger the clothes and toothbrush wheres my MFT....... lol

 

[Guest111]

My test gear is one of the first things that gets packed!

We went on holiday last year and the site owner's jcb broke down just near where we,d pitched,anyway he was stood cursing it and shaking his head,out came the big toolbox,rubber gloves on and away I went,ten minutes later fault found,repaired and machine started.The guy was amazed he said it would have took him longer to get his gear let alone find it and fix it,sadly she's stopped me carrying the large tool chest in the car but I still carry my large cantilever toolbox.lol

 

[Geordie Spark]

I think you're right about brushing up ob section 7!
I heard from someone else that the owner is thinking about selling the site thus why he needs the report! I've not heard ut from the horses mouth though! I wouldn't imagine that he'll be keen on spending money on remedials!!!

Aye, he's after a fur coat & no knickers job.

 

[telectrix]

useful when you ain't got a duvet.

 

[Geordie Spark]

useful when you ain't got a duvet.

That's one of them things ye keep doves in innit? .... Like a hen hoose on stilts.