Open Earth

[ukracer]

Being the proud owner of @Robotstar5 plug in AC tester and therefore an expert on all things electric , and i was replacing the carpet in my computer section of the back room, I decided to plug it in and check out the plugs I hD concerns about a while back.

It's a double plug and it shows "open earth" according to the tester on both sockets.

Does this mean there is a broken earth between those sockets and the supply?

 

[Barking Mat]

Run a continuity check between your fuse box earth and the earth on the plugs, that'll tell you.

 

[sg66]

You should get 240v from live and earth with volt meter

 

[ukracer]

Run a continuity check between your fuse box earth and the earth on the plugs, that'll tell you.

Yep I guess it would but I assumed that's what the martindale gizmo was for.

I have just been round the house plugging it into as many sockets as I can.
In all the others I get 4 green lights.
3 across the bottom and the top left.
So I am hoping that configuration means alls well.

 

[Barking Mat]

You should get 240v from live and earth with volt meter

Damn good point.

 

[ukracer]

You should get 240v from live and earth with volt meter

If I don't is that bad? I will test it tomorrow as its too late to mess with live electrics.

 

[qwakers]

if you do that it should trip the rcd iirc

 

[sg66]

if you do that it should trip the rcd iirc

I do it often, only trips when I use my fingers instead of the meter, never tripped with meter

 

[sg66]

Ohh BTW how do you think plug testers work out the earth is there and working

 

[ukracer]

I do it often, only trips when I use my fingers instead of the meter, never tripped with meter

Fingers....OMG

 

[ukracer]

Ohh BTW how do you think plug testers work out the earth is there and working

I don't know but I know I don't have test cables long enough to reach the plug and the main earth in the supply box.

 

[not done it yet]

if you do that it should trip the rcd iirc

Most digi multimeters have an input resistance of, or in excess of, 10 MOhm. 240 Volts would drive micro amps through the meter to earth. RCDs need mA to cause a trip. Hence no trip.

 

[sg66]

It happens

My first encounter with electricity was at the age of 9 I think, transformer for train set was broke, I took one out of a radio, in the process of bodging it together I tried twisting together a wire that I had plugged in at the wall.


Electricity is a funny old thing, I've had more interaction with it than is certainly healthy yet some get one jolt and that's it.

 

[brightspark]

if you do that it should trip the rcd iirc

it wont with just a voltage tester just if a load is applied is the socket on a ring,main or is it spured off. if its on a spur the eath cable will be out at its conection on the ring. if the sockets on the ring main the earth cable will be disconected at 2 points

 

[Dave-sparks]

You should get 240v from live and earth with volt meter

You should yes, but this can't replace a continuity test.

 

[Robotstar5]

if you do that it should trip the rcd iirc

Some testers recommend "charging" them up across L & N before testing L to earth to prevent RCD tripping

 

[Hopefuldave]

Right way to do it is to go back to the distribution unit, switch off at the main switch, find the earths for that ring, separate them and check they show a short - if they do, open the socket to see whether the two incoming earths (twisted together, probably) are in the earth terminal properly.

Dave H. (the other one)

 

[indy4x]

Electricity is a funny old thing, I've had more interaction with it than is certainly healthy yet some get one jolt and that's it.

Same here, not for many many years but as a youngster I did have the odd mishap and still dabble with electricity many years on

 

[sg66]

@Hopefuldave

I'm not doubting you, for quickness on a ring I tend to just split it at a socket which ever side has lost a line stands out and I know which direction to go looking, plug tester is fine for detecting which faulty socket, I prefer meter, this is just what I've learnt over time.

 

[dobbslc]

You can test the end to end continuity of the "ring" to see if it's broken, you can do it at the dist board but it can be fiddly to separate the ends so I often work at a socket. Turn off the supply and disconnect one of the sockets (start at the one that's not working as it might just have a broken wire) measure the continuity between both lives then both neutrals then both earths, its better if you have a multimeter to get an accurate reading in ohms. You should have continuity on all 3 tests if not go looking for the break.
Beware you might have a radial spur (or any other combination of DIY Dave lash ups!) so that won't give you continuity on this test.