Earthing Electrical

[missismiggins]

Hi,

hope someone with a bit of knowledge here such as Crossy can answer a couple of questions I have regarding a good ground connection.

When we built the house, the electrics were installed by a local guy who seemed to understand grounding to some degree (he bought all 3 pin sockets).

We had all of the grounds connected to a 2 metre copper rod driven into the ground close to the house.

Since then, I bought a surge protected do everything extension for my PC, which also has a "grounding Check LED"

When I use this extension in the downstairs sockets near the grounding point, the LED indicates a ground connection, however, when I use it further away, it does not indicate ground.

I hve checked the grounds from the different sockets and there is continuity...mmmmm.

Secondly I installed lightening rods on my roof, the roof is approx. 20m long (typical gable roof) and has three rods, one at each end and one in the middle.

The are connected to a large diameter copper conductor which runs from each end of the roof to the two opposite diagnol ends of the roof.

this then connects to 3 x 2 meter rods placed in a triangular pattern approx 1m perimeter (there are two sets of three rods, one at either side (diaganolly) of the house.

Would it be safe to connect my earth from the sockets to these points too, or, am I in danger of zapping everything in the house should a bolt hit the roof?

Cheers

[Crossy]

'ello Missis

OK. The easy one first, under NO CIRCUMSTANCES connect your lightning protection with your electrical ground, you stand a serious chance of shoving big nasties into your house wiring if you should get a strike! Make sure your electrical ground rod as a good distance from the lightning grounds (at least 2m, further preferably) for the same reason.

Testing grounds properly requires specialist kit and knowledge, since we don't have the kit or the knowledge, try this. Get your meter and check you have 220V between live and ground at all your outlets, that will at least ensure there is a ground of sorts (and that L and N are not transposed which would also cause your 'ground indicator' not to light). If these tests are satisfactory come back to us

Just in case you're not sure:-

Edited May 28, 2008 by Crossy

[missismiggins]

'ello Missis

OK. The easy one first, under NO CIRCUMSTANCES connect your lightning protection with your electrical ground, you stand a serious chance of shoving big nasties into your house wiring if you should get a strike! Make sure your electrical ground rod as a good distance from the lightning grounds (at least 2m, further preferably) for the same reason.

Testing grounds properly requires specialist kit and knowledge, since we don't have the kit or the knowledge, try this. Get your meter and check you have 220V between live and ground at all your outlets, that will at least ensure there is a ground of sorts (and that L and N are not transposed which would also cause your 'ground indicator' not to light). If these tests are satisfactory come back to us

Just in case you're not sure:-

Many thanks, will check and let you know. (by the way I sent you a post on your roofing question and if you want some scans from the brochure pm me with an e mail and I'll send them to you - I think the company is Chang)

[missismiggins]

Hi Crossy,

did as you suggested, the sockets that do not light up the ground LED are correct, I am getting 220 between earth and live, (and am getting about 2 volts between neutral and earth?)

I suppose the only sure way is getting something like a Megger/Megga to test - do you know of any other way - all of the RCBs on the Square D box seem OK and I also have a SAFE T CUT fitted before the square D where the mains enters.

I can attest from past stupidity that they actually cut out..LOL

Any suggestions, or could it just be a crappy extension gimmick?

cheers

[Crossy]

Hmmm, a little worrying that the LED comes on with some outlets and not others, even though I'd class it as a gimmick I would expect it to do the same everywhere. The outlets that DO put the light on are wired correctly too, aren't they?

The fact that you have a voltage between N and G indicates that you don't have a MEN link in your consumer unit (if you DO have MEN then you have another problem).

I wouldn't worry right now since you're getting the correct voltages at the outlets.

Anyone got any bright ideas? I was hoping for crossed L&N at the 'no LED' outlets

[missismiggins]

AHA!

the ones that do light the earth LED ARE WRONG WAY ROUND!!!!

and no I don't have a MEN, so any ideas as to the why's and the wherefores?

Cheers

[Crossy]

AHA!

the ones that do light the earth LED ARE WRONG WAY ROUND!!!!

and no I don't have a MEN, so any ideas as to the why's and the wherefores?

So evidently, your flashy extension lead is also wrong, two wrongs make a light

Don't worry right now about the MEN, you have a ground and ELCB so you're fine. Task for another day, is to check if MEN is implemented in the other houses on the same transformer, if it is then you can safely add a MEN link, otherwise leave well alone!

Since a MEN link is clearly shown in the Saf-T-Cut installation book I suspect that you're in an area without this system (and it would be hazardous to add a link to just your installation).

EDIT Just as a final check before you change anything, check that the incoming live really is live (use your neon, or meter to ground) and that the whole supply is not reversed.

Edited May 28, 2008 by Crossy

[Pink Mist]

2 volts between neutral and earth could be the measuring instument, or bad MEN connection, you need to check impedance between each outlet and earth at the switchboard.

here in Oz at the moment I think we are down to 1 ohm max at any point to earth from earth.

[Crossy]

2 volts between neutral and earth could be the measuring instument, or bad MEN connection, you need to check impedance between each outlet and earth at the switchboard.

here in Oz at the moment I think we are down to 1 ohm max at any point to earth from earth.

Yeah, he's not got MEN at present, got to check if it's implemented in the village So 2V is just about OK, with an ELCB he's fine

Edited May 28, 2008 by Crossy

[Forkinhades]

yes you need to do a Impedance test at all your sockets, if they are protected by an 30 amp MCB, you are allowed a reading of up to 1.5 ohms (current english regs on a 30 amp type 'b') or 0.75 if its a type C

The voltage between N and E would suggest a loose connection maybe at one of your sockets on the earth terminal

[Crossy]

yes you need to do a Impedance test at all your sockets, if they are protected by an 30 amp MCB, you are allowed a reading of up to 1.5 ohms (current english regs on a 30 amp type 'b') or 0.75 if its a type C

The voltage between N and E would suggest a loose connection maybe at one of your sockets on the earth terminal

Agreed, but right now he has NO MEN link, just a ground stake. Until he verifies that other houses have MEN he should not install a link.

[Pink Mist]

remember a couple of years ago, Crossy, I said it could be difficult to give specific electrical advice, you do a great job mate.

[petercsea]

remember a couple of years ago, Crossy, I said it could be difficult to give specific electrical advice, you do a great job mate.

I second that he is a good giver of advice and excellent communicator. I'm grateful.

Had the new meter installed yesterday (30/100 Amp). Nothing as a follow up though.

Would you know if you have to specifically request testing in effect of a new installation: house and supply, directly from the PEA or is it up to the homeowner to find a competent electrician?

Any thoughts Crossy?

[Crossy]

remember a couple of years ago, Crossy, I said it could be difficult to give specific electrical advice, you do a great job mate.

I second that he is a good giver of advice and excellent communicator. I'm grateful.

Had the new meter installed yesterday (30/100 Amp). Nothing as a follow up though.

Would you know if you have to specifically request testing in effect of a new installation: house and supply, directly from the PEA or is it up to the homeowner to find a competent electrician?

Any thoughts Crossy?

Careful, I'll get a head swelling

AFAIK once a new build has had the (apparently cursory) official inspection and MEA/PEA have connected the permanent supply you're on your own. You can do pretty much what you like to the installation on 'your' side of the meter and nobody will bat an eye. This 'inspection' is part of the supply connection process and as such is provided by MEA/PEA, what (if) it costs I don't know.

Hopefully someone who's gone through the process recently will pop up and tell us

If they've replaced the meter then I'd be seriously tempted to check you've got L and N the right way round (use your trusty neon screwdriver).