No Earth?

[GarryJ]

Evening all,

I have arranged to go and see a job on Wednesday with the following problem: The customer has a disabled son and is eligible for a heating grant, however when they came out to survey to install it they told her she had no earth present at her supply and would have to get one installed before they would begin work. As i said I have not seen it yet so whether there is one present and just too high reading I don't know. It is a rural cottage with an overhead supply

I am just looking for some advice as I have not done much work on TT systems and I was wondering if someone would be kind enough to advise me on how to go about it/ best earth rod to install etc

Any help appreciated

 

[GLENNSPARK]

5/8" rods.....get three of em.....you will need two connectors and a driving stud n all.....you should dig a pit first in the place you have chosen to drive the rod/s in to make sure you dont launch the rod through any buried services....lol..go for someware about a meter away from the house....so as not to intercept any foundations.....drive the first one in using the protective driving cap.....when its just short of all the way.....use a connector to screw the second rod on.....start driving it in again.....

 

[GarryJ]

Thanks for the reply Glennspark. So three rods about a meter from the house and inter connect them. And what about the regs and best way of running the cable? Put a protective ducting in place that will suitably protect the cable until it enters the house? And then just connect in to the rods at one end and to the MET in the consumer unit? 25mm2 Green and Yellow?
Cheers for the advice as I say I have hardly carried out work relating to this scenario.

 

[SPARTYKUS]

Where's Richy3333 when you need him. He's an expert and down the road!

 

[not clever]

Everything you need apart from the 10mm green/yellow & conduit.
14mm x 1200mm Earth Rod ( 5/8" x 4ft )

 

[jaydee81]

dont forget the rcds lol

 

[telectrix]

Thanks for the reply Glennspark. So three rods about a meter from the house and inter connect them. And what about the regs and best way of running the cable? Put a protective ducting in place that will suitably protect the cable until it enters the house? And then just connect in to the rods at one end and to the MET in the consumer unit? 25mm2 Green and Yellow?
Cheers for the advice as I say I have hardly carried out work relating to this scenario.

you don't sink 3 separate rods, you screw 'em together to make 1 long one. i would check if pme is available. sometimes pme is supplied to the house, but not connected to the CU.

 

[GarryJ]

Thanks all for your help. I have not seen it yet, its booked in for Wednesday so I will know better after that. I suggested to her to ask her DNO to supply her with an adequate earth but she said they came out and were not willing to provide it free of charge.

Yes so just sink the rods as far as they will go basically? and as for the cable, is 10mm2 G+Y suffice if it is just a couple of meters from the house with a ducting in place to provide mechanical protection for the cable and connect it straight into the MET?

Cheers again

 

[GarryJ]

P.S and just ensure all circuits are protected by 30mA RCD?

 

[GLENNSPARK]

P.S and just ensure all circuits are protected by 30mA RCD?

yep...thats fault protection (for TT)

 

[GLENNSPARK]

get yoursen one of those plastic inspection pits as well...the ones with the lid on em......use that to protect the cable termination on the rod whilst still allowing access to the termination....

 

[Guitarist]

Not wishing to sound too negative, but if it's something you are really unsure about, either have a good chat with your scheme provider first, or tell the customer you are too busy. I wouldn't recommend anyone takes on work that they really have no experience in whatsoever. You can't play guessing games with peoples' lives.

 

[Marvo]

Nobody's mentioned yet you'll need to test the Ra of the new earth rod. There's always some energetic discussion about a safe impedance you should be trying to achieve but I'll start the ball rolling with a suggestion of <10ohms if it's a pure TT system.

 

[GarryJ]

Fair point guitarist, I have heard myself telling people that before also. I mostly do domestic and commercial work and have just never happened to come across personally actually installing rods/dealing with TT systems. I understand where your coming from but the guys on here is usually really helpful and once I have seen the job will do all the required research and ensure I am going to carry out the works correctly and to a good standard before I start if I even get it. I usually just come on here and read posts daily never usually post much

 

[GLENNSPARK]

Nobody's mentioned yet you'll need to test the Ra of the new earth rod. There's always some energetic discussion about a safe impedance you should be trying to achieve but I'll start the ball rolling with a suggestion of <10ohms if it's a pure TT system.

21 ohms..

- - - Updated - - -

decent rods though driven deep should get that down...

 

[harrod58]

Remember the 30mA RCDs!!!

 

[dim_bulb]

I think under 200 ohms in deemed stable but with and rcd couldnt it be 1667

Right where's my hat I'm gona need it

 

[Octopus]

Actually I'd be using my own skills and knowledge to check the ACTUAL situation before spending any money.

Got a call recently from a rather worried lady saying her house was using her metal garage door as the earth. Sure enough there was 10mm GY running to the garage door, but also a nice fairly recent piece of 16mm GY running into the lecky box!

 

[ayjay]

if the soils full of rocks and stones well------
if its chalk well-----
best of luck