Found an ELCB

[Click-Sure]

Well, it took a while, but I finally found an in-service ELCB, which I promptly took out of service when I changed out the consumer units, it was 'protecting' the supply to the storage heaters, which it wasn't actually doing at all because of the way the installations earth electrode was connected

Very well built unit too, the switch feels like a bolt-action rifle.

Untitled

• Click-Sure
• 22 Jan 2010
• 2

Untitled

• Click-Sure
• 22 Jan 2010
• 1

 

[Lectrician]

Loads of them around here still.....

The good old crabtree!

Did you see my recent pic of one of these 'converted' into an RCD?

 

[starspark]

loads wylex ones still in use in communal hallways where i work too!really old bill contactors,two wire photocells and rectifier kits all in same installs as well although they are due to be upgraded shortly!!dont make them like they used to!

 

[AndyPRK]

So remind me how these need to be wired to work ?

The installations earth needs to be connected though this to the electrode. (TT)

And no water/gas pipe bonding should be present.

What happens with things like immersion heaters that are earthed, with a metal water main ?

 

[Spark123]

Basically all extraneous and exposed conductive parts are connected via the MET to one of the ELCBs terminals.
The earth electrode is connected to a different ELCB terminal.
If the voltage of the MET becomes 50v above that of the electrode then the ELCB trips.
Owing to parallel paths from your metal water main etc, these are now considered unreliable and haven't been recognised by the regs since the early 1980s iirc.

 

[AndyPRK]

These are the same conditions as when it was installed, so it must have worked then ?

I guess this is one too

The wire thru the holes goes to the earth rod.
No water/gas bonding.

 

[bloxy]

I've got one in my meter box 'protecting' my installation.

Planning a CU change soon as I know it is obsolete.

 

[bloxy]

So remind me how these need to be wired to work ?

The installations earth needs to be connected though this to the electrode. (TT)

And no water/gas pipe bonding should be present.

What happens with things like immersion heaters that are earthed, with a metal water main ?

That's how mine was when we moved in in the early 80s. House built in mid-late 70s with CU & ELCB in meter box.

I thought you needed main bonding to the MET in the CU otherwise the water main gives a parallel path to earth and the thing doesn't trip. I added main bonding connected back to the earth block in the CU (no separate MET) shortly after we moved in. All going to be re done soon to current standards.

Having drilled through a cable (not in a safe zone) some years ago, it definitely worked! And it still operates on the test button.