Neutralised at main switch (elcb)

autumnalcore

Just moved into a house built 1962. Bare wire earth's are neutralised at the neutral on the main switch which is a museum piece crabtree ELCB. Not unusual shenanigans for the era.

At some point an electric shower has been fitted the sparks fitted RCD and MCB in a small garage style consumer and appropriately sized cable and that all looks fine apart from one thing:
Sparks has run the shower earth outside the consumer unit directly to ElCB and sleeved it in blue. Seems unusual to sleeve the earth as a neutral and why not use the earth terminals inside the unit and run an earth coloured wire to the existing neutralisation point?

2011

Where was the earth connected? To the neutral of the ELCB?
Obviously it should have been connected to the MET.

Back in the day earths were frequently sleeved blue as earth sleeving was practically nonexistent. So it was blue or nothing.

autumnalcore

2011 wrote: »

Where was the earth connected? To the neutral of the ELCB?
Obviously it should have been connected to the MET.

Back in the day earths were frequently sleeved blue as earth sleeving was practically nonexistent. So it was blue or nothing.

Thanks for reply. Earths are connected to earth terminal on the elcb and on closed inspection there is no neutralising conductor the black wire going behind the meter board that I assumed was neutralising wire is a small transparent insulated earth maybe 2.5mm to 4mm that was taped with black insulation tape for some reason.

I was trying to hold off on getting it replaced. I guess I should get a REC to install a new earth rod and earth cable neutralising conductor and and tails (currently 4mm2l in advance of the smart meters being installed.

2011

Neutralizing is normally done at the cut out. However it can be hit and miss in old installations. There should be only one neutralizing point in the installation.

The earth for the sub board should come from the MET (main earth terminal) located in the main board. The neutral for the sub board should come from the main neutral bar in the main board.

Tails should be a minimum of 16 mm sq.

FYI: From a legal perspective only a REC (or an electrician doing work for a REC) should work on a domestic distribution board.

autumnalcore

2011 wrote: »

Neutralizing is normally done at the cut out. However it can be hit and miss in old installations. There should be only one neutralizing point in the installation.

The earth for the sub board should come from the MET (main earth terminal) located in the main board. The neutral for the sub board should come from the main neutral bar in the main board.

Tails should be a minimum of 16 mm sq.

FYI: From a legal perspective only a REC (or an electrician doing work for a REC) should work on a domestic distribution board.

Thanks, I know was enquiring as I want to know what to ask to be done as the sparks that did my parents and brothers houses nearby had very different ideas of what was acceptable to leave untouched in an old installation. The guy that did my partents house left the original tails.

2011

autumnalcore wrote: »

The guy that did my partents house left the original tails.

That should be of immediate concern. The normal rating for a main fuse for a domestic installation is 63A and a 4 mm sq. cable can not safely carry a current approaching this. Remember the fuse is there to protect the cable. Off the top of my head I would be reluctant to protect a 4 mm sq. cable with a protective device rated above 25A.

When you consider that a 63 main fuse can carry a current well above 63A for a protracted period it becomes clear that the tails could be blazing away before the fuse will operate :eek:

It sounds like you need to get the entire installation checked by an experienced professional.