Circuit tripping VO ELCB

[Corjj]

I'm having an issue with the downstairs sockets circuit in the house tripping the old Crabtree ELCB which is fitted inline with the fuse box. This has suddenly started to do this.
I've been trying to work out what is going on and it seems that higher powered items trip it (kettle, microwave, toaster, etc) and other items don't seem to.

Other observations:
1) sometimes it takes a little time before the ELCB will stay in the reset position, even when the downstairs circuit is isolated on the fuse box. This usually happens if it has tripped a few times.

2) it doesntly like resetting unless the whole fuse box isolator is switched off then back on again. I.e. the ELCB may not reset if the individual circuit is isolated on the fuse box without the main isolator on the box being switched off.

Any thoughts appreciated!

Obviously getting an electrician out may be on the cards.

 

[RF Lighting]

Do you have any other form of earth leakage protection within your installation such as an RCD in your consumer unit?

Can you post a wider shot of your installation to include the incoming supply and any earth wires attached to it and your fuse box / consumer unit?

I you are probably going to require the services of an electrician whatever happens as VOELCBs have not been permitted for many decades now as they are often bypassed (not deliberately) rendering them useless.

 

[ericmark]

The ELCB-v shown have been outlawed for years, they were only used for a very short time, museum piece. It needs changing nothing else to be said.

 

[Corjj]

No other RCDs or any other protection at source. I have some RCD sockets on the garage circuit.

I was intending to have it replaced as part of some garage conversion work I'm planning later next year as it's not a great setup. I believe the earth will require upgrading too.

Do you have any other form of earth leakage protection within your installation such as an RCD in your consumer unit?

Can you post a wider shot of your installation to include the incoming supply and any earth wires attached to it and your fuse box / consumer unit?

I you are probably going to require the services of an electrician whatever happens as VOELCBs have not been permitted for many decades now as they are often bypassed (not deliberately) rendering them useless.

 

[securespark]

IIRC, the vo ELCB was first used in 1966 and deleted from the regs in January 1985, when it became compulsory to use the 15th edition.
The full introduction of the 15th was delayed 4 years due to confusion surrounding the new regs.

 

[ericmark]

The ELCB-v measures the voltage between true earth and house bonding and switches off when the voltage difference exceeds 50 volt, they were used to allow an earth rod which would not pass enough current to rupture a fuse, but they were not successful, and to easy for the bonding in the house to get linked to the true earth so the voltage could not raise to a point where they trip.

I was working abroad when they became popular so never really got involved, I know when a RCD is fed from a supply protected by an ELCB-v the RCD will not trip with the tester, I have only found one in use, and it was disabled and a RCD fitted, and all I had to do to disable it was fit a new earth rod, this is why they are not used any more.

The problem is the ELCB was replaced with the 100 mA RCD, however the 100 mA RCD is now considered as not being sensitive enough so we now use 30 mA and 30 mA is OK with a split board where you have two or more, but it is far too easy to trip, so using one 30 mA for all is asking for trouble. So really the fuse box needs replacing with a modern consumer unit.

I will guess some where your neutral and earth have got linked, which is causing the tripping with heavy loads, but as I found when I came across one of these units, non of my test equipment is any good, as the modern RCD tester it not designed to work with these units.

As an emergency measure in my own house I would fit a 100 mA RCD to replace it, but in some one else's house I would not want to do that, as we all know there is no such thing as temporary, once it stops tripping people forget about it. It is all well and good saying you need the fuse box swapping for a consumer unit, but there is clearly also a fault, so it needs some one with a 500 volt insulation tester to find the fault as well.

Can't see how we on a forum can help, it is not a DIY job.

 

[plugwash]

I'd agree, what needs to happen is

1. try to find the fault with an insulation tester (though that may not be possible, either because the fault is intermittent or because it's actually the ELCB that is faulty) and
2. Replace the old fusebox, henly block and ELCB with a modern consumer unit with RCBOs (don't go for a dual-rcd unit in a case like this).

Neither is really a DIY job.

 

[AndyPRK]

Yes get a new cu if you can before Xmas and get the electrician the fault find first.

Get all rcbo. Fusebox brand is good value

I wouldn’t delay too much as the latest regulations will mandate extra expensive things like afd

 

[Corjj]

Thanks all for your really helpful answers. I will arrange for an electrician to come in and replace with new consumer unit and isolator, preferably with RCBOs and have anything else rectified at the same time.

I will just have to discuss with them future plans to make sure suitable provision is made for the extra space in consumer unit when when the conversion is done.

 

[SUNRAY]

I don't habitually advise to go straight for the jugular but in this case I agree with all the others to get an electrician in quickly to look for the fault and get rid of the ELCB. THE most obvious solution is a new consumer unit.

 

[Corjj]

To update, I've had an electrician I've used before and been happy with quote for replacing the consumer unit and doing a few minor circuit changes. New water and gas bonding plus new earth rod.

I'm supplying the consumer unit and RCBOs as I have a preferred one which fits the space and the supplier he normally uses doesn't have an equivalent (Fusebox 21 way duplex - I only need 15 ways total for final conversion and future circuits but this seemed a good fit and reasonably reputable for the price). I will be sure to get the ones as requested by him with B curve and I also I think I will get type A over type AC as that seems worth it for the extra DC fault protection.

The price has come in at £650 Inc VAT for labour with me supplying the consumer unit and RCBOs, him supplying the tails and other bits. Does this seem reasonable? I've attached a clip from the quote. Thanks in advance!

 

[sparxxxx]

He should carry out a full test before replacing the CU, this to rectify any faults that may effect operation of RCBO's.

Has he explained benefits of spd's and affd's? NB affd's might need one extra module space per affd

The price seems ok.

 

[AndyPRK]

AFFD's are about £150 per circuit. (though you don't tend to fit them on the small 6A circuits)
A fusebox brand probably comes with an SPD

 

[sparxxxx]

AFFD's are about £150 per circuit.

Is that all, I had no idea

though you don't tend to fit them on the small 6A circuits

Apart from cost, why not?

A fusebox brand probably comes with an SPD.

Do you mean as an individual item, ie not built in.

 

[AndyPRK]

Maybe I got the 6A bit wrong. They don't tend to trip very well on ARCs on low current circuits though.
The SPD is a module fitted next to the main switch.