What do you think of this?

[Adam_151]

No, a neon screwdriver is no good here (whether they are any good anywhere is a completely separate issue)

What lucia means is a continuity tester made with a lamp (or bell) and battery...

With the circuit isolated (preferably DP isolation*), connect one terminal of your battery to your main earthing terminal near your fuseboard (or if not accessble, any other point known to be connected to it, bonding for example if you physically see that that it connected both ends and is unbroken. To the other terminal of your battery a long lead, connect the end of that to a lamp of correct volatage for the battery, the other side of the lamp, a foot or so of wire with a bare end the other end. Test the lamp by touching the bared end to the point you have earthed the battery lead to and the lamp should work, now go around and use the bared end to test at each point that should be earthed.

Its a rather crude version of the R2 test, but will tell you if you have a path back to the MET



*Otherwise a a broken cpc coupled with N-E fault after the break could lead to false results... so If you can, knock off the main switch while you do this

 

[Adam_151]

This is strictly advice for a DIYer, of course. But if you have no RCD and connect a lamp between live and earth it will light at full brightness to indicate that the cpc is indeed connected at the source of the circuit. But there's no harm in using a visual check at each end of each cable.

Bad luck for anyone who happens to be in contact with an exposed conductive part downstream when the lamp is applied to a point which does indeed have an open circuit cpc, eh

 

[Gigagator]

Thanks for the replies. I've never actually used the test screwdriver anyway, its just sat in my toolbox. I do have a multimeter though.

There is no RCD protection in my CU. If I just put the pos and neg leads from the multimeter onto the live and earth wires respectively, could this give me an indication of whether the earth wire is suitable to be reconnected?

Thanks

 

[cozycats]

With the appropriate fuse/mcb off/pulled you can test your earth connection at the box in the pic by testing earth-NEUTRAL, this should give you a VERY LOW continuity reading if on a TNS or TNCS supply, if on a TT supply the reading may be vastly higher, possibly a few hundred ohms. See the wicki re TNS TT etc

 

[jon47]

I think an r1+r2 test would be better than using the 'test lamp' method.

 

[PrinceofDarkness]

Gigagator: Firstly, have a visual check to make sure that the cpc's havent been snipped off elsewhere. Confirm that fact here and then you can use your test instrument, such as it is.........


Lucia.

 

[Gigagator]

All of the bare earth wires are snipped off at every point on the upstairs lighting circuit i.e. at the switches, at the light fittings and at the junction in the attic as shown. I'm not sure about the downstairs lighting circuit junction as I can't lift floorboards to get at it but the situation is much the same downstairs.

However, I'm not sure if the earth wires have been disconnected or cut off in the CU as I have never opened it. Here is a picture of my CU in the hallway - usually has a cover over it.

Untitled

• Gigagator
• 1 Jan 2011
• 2

 

[1john]

Remeber that when you open that board that the main switch is OFF also remember that the two grey cables that come in from the bottom of the board to the top of the main switch will always be LIVE!!

 

[PrinceofDarkness]

Hello Adam_151, and a Happy New Year to you.

I don't accept the premise of your most recent post, because a test lamp between a live and o/c cpc for such a short duration as a 'test' would result in no current flowing and no illumination of the temporary lamp.

Many people here rely on the 'better be safe' policy when dealing with DIYers - they must have all the test instruments, observe all the Regulations, seek professional advice etc .....

Well it just won't do for a DIYer with such limited rescources. The best we can do for a DIYer is to advise him in such a way, considering his limitations, so that he doesn't cause harm to himself and his fellow occupants.

I have the confidence to do just that - without screaming Part-P and all that jazz.

Lucia.

 

[Gigagator]

Okay, I am going to have a look inside the CU tomorrow. I understand that some parts will remain live so I will be cautious.

I'll also take a photo of the inside for your curiosity. Judging by the state of the work elsewhere in the house, no doubt the CU will be equally worrying.

Thanks for the advice.

 

[martinxxxxxx]

Hi there

Purely out of interest - is there a lead seal on the main fuse?

Couldn't see it in the photo - so just wondered.

Martin

 

[Gigagator]

Hi there Martin,

I'm not sure to be honest. I will check tomorrow - you mean on the unit farthest to the left, correct?

Watching the darts on Sky Sports right now, it must take priority

 

[AndyPRK]

and replace it with a standard 30A joint box (20A would do, but 30A has greater space for multi-cable terminations).

Going to need one with at least 4 terminals by the look of it.
These tend to come in 20A flavour.

 

[1john]

Or use a 30A one and a connector block for the switch wires, there's room enough inside.

 

[securespark]

I find 30A terminals a bit too big for lighting cables.

A good quality 20A one will have plenty of room for the terminations, plus will have a 4th terminal.

Don't buy the cheap white ones, their terminals are much smaller.