Earth wire to fuse box

jamesy · 9 Jun 2003

Hi

Anyone know what the main earth cable from a fuse box should go to? I am rewiring my flat into the existing fuse box and am concerned by the fact that my earth wire just seems to be connected to the wall.

Help me I don't want to fry myself.

cobweb · 9 Jun 2003

The fuse box should have an earth block – usually brass and with half a dozen or so insert points for the earth wires – from one side there should be the main grounding (earth) conductor from outside the house (you shouldn’t need to touch this at all), and from the other there should be a collection of earth conductors that travel to each outlet point/light fitting Etc. in your house.

If your earths are simply bunched together and attached to the wall (!!!) as you say, then you have a big problem and should get a qualified electrician (or your electricity supply company) in to check your electrical system out thoroughly.

A home that isn’t earthed properly is a scary and potentially lethal prospect.

MANDATE · 9 Jun 2003

The earth block within the fuse box will probabley have 1 terminal hole larger than the rest.
I have recently removed mine to examine it closely, after replacement I fitted another earth terminal block below the fusebox ( £3-00 B & Q).
I now have a 16 mm earth wire in the following places
earth block in fusebox to external earth block
external earthblock to lead sheath of incoming mains cable (strap connector)
external earthblock to copper pipe of gas supply ( strap connector)
external earthblock to second fuse box
To date all earth wires within the property lead back to one of the fuse boxes which in turn goes to the main earth.
I am in the process of fitting another earth wire from the incoming water main to the external earthblock.

Gees · 11 Jun 2003

only works on water main if its NOT plastic.
Drve in an earth rod if you want to be CERTAIN then have earth loop impedance test carried out.

breezer · 11 Jun 2003

for more information about earth bonding (connecting your pipes to earth and together see this

jamesy · 13 Jun 2003

Thanks for all that info lads.

Unfortunately I am still not entirely clear on whether I have a problem. I have lots of earth terminals in my fuse box which all the earths from the rings, etc are connected to.

The problem is that in the main earth connection there is a very old lead which is covered in that fabric type stuff. I t doesn't go to the meter but into the wall and dissapears which means that I don't know where it goes. I am in a first floor flat.

Should there be any kind of an earth wire coming from the electricity meter where my live and neutral come from?

Gees · 13 Jun 2003

Sorry to repeat myself. Have an electrician carry out an earth loop impedance test. This test takes about 10 seconds and measures the resistance from your LIVE mains connection back to the substation through the substation transformer to the earth and neutral( that are connected together at this point ) thence back to your earth connection in your home.
I carry out this test as part of my job installing washing machines.
It will tell you Immediatly if your installation is satisfactory.
Not having a proper earth connection is dangerous and can lead to severe shock and possible death.

see http://www.phoenix-elec.com/fixedtest.htm

Gees

MANDATE · 14 Jun 2003

There is no 'earth' wire connected to the meter.
All earths from your sockets ,lights etc go to the earth terminal in your fuse box, then a larger earth wire goes from fuse box to the lead sheath covering of your incoming mains cable.
I understand that where the mains comes in by overhead cable you need to provide your own earth by means of a copper coated earth rod that is driven into the ground( available from B & Q approx £10)
You need to examine the position where the main supply 'live' and 'neutral' exit the cable (usually where the mains enters the building) to establish if any earth cable is connected at that point.
If necessary have a look at a relatives meter cupboard

breezer · 14 Jun 2003

that is true unless you have a p.m.e installation (don't worry about it, trust me) but if you have a p.m.e installation there will be a note saying so, but you still get a main earth point to connect to.

I should suspect there is an earth point somewhere just not that obvious as to where it is.

Gees · 15 Jun 2003

P.M.E. Explanation

In a PME system, the main earthing terminal of an installation is connected to the neutral of the electricity service at the consumers premises. All metallic surfaces within the building, including gas pipes, water pipes, central heating systems and accessible structural steelwork are bonded together at the consumer unit. This gives the consumer an earth of very high reliability and of low impedance. Under normal circumstances a small voltage may appear between a PME earth and the true earth potential measured outside the building as a result of voltage drop in the neutral of the electricity supply company's system. Under very rare fault conditions, such as a rupture of the neutral conductor on the supply company's system, a higher potential difference may appear which could, in theory, rise to phase-to-neutral voltage (240V). Because all the metalwork in the building is bonded together, the shock hazard is minimised because everything is at the same potential - even though this may be different from the outside earth potential.

Gees

breezer · 15 Jun 2003

that's easy for you to say, but i didn't want to type it

Gees · 15 Jun 2003

I nicked it from another site

jamesy · 16 Jun 2003

Thanks for that lads

You have set my mind at rest. I think that my system will be ok but I will get an electrician in to do an impedence test as you reccomend. That should still be a bit cheaper than a full rewire!

Cheers again

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Earth wire to fuse box

breezer

breezer

breezer

Similar threads