Loop electrics changed by national grid but left with consumer unit issues?

[laneycakes]

My folks had a smart heater installed a couple of months back-during the install some seal or something was broken by the engineer. When another chap came to fix it, they discovered my folks were on a looped electrics system with their neighbour and said that it had to be changed as it’s now illegal

So national grid have been out and made the changes…however it’s left my folks with an issue with the consumer unit/fuse box. Just to note this was working perfectly before these works took place.

Basically my dad had to switch off the electric to test a UPS (separate issue with BT digital voice) so he flicked the master trip switch…but when he came to put it back on it wouldn’t work. National grid came out, and they managed to get it working by switching all the individual trips off, then putting main trip on, then switching the individual ones on one by one. They then sent out the contractors who did the cabling to check that was all ok.

Those contractors say the work they did was fine, but there’s now too much power for that consumer unit to handle, and that my parents have to arrange and pay for a new unit. This doesn’t feel right to me. At no point in these works did anyone suggest my folks would have to get any work done serstrly I’d pay for it. So to my mind this is national grids issue to fix? Am I right?

I’m also worried about the safety of it now. If they are right and there’s too much power for the consumer unit to handle is it now potentially unsafe? The only way they can get the leccy back on if they trip the main switch is this process of switching each individual trip off.

Both parents are in their 70s and classed as disabled so it’s a worry. Any advice appreciated.

 

[Murdochcat]

A looped supply is not illegal

 

[ericmark]

I am guessing, but my guess is they have solar panels and a battery similar to myself, so the supply is size of DNO fuse plus what the inverter can supply is now over the rating of some critical part of the consumer unit, maybe a 63 amp RCD where it should be a 100 amp or something like that?

And it seems likely the RCD is tripping.

Again a guess, I suspect you have an TN-C-S supply, and the C stands for combined, and it means at some point the neutral and earth are linked, but the more cable between where linked and where separated which is what the S stands for, the more will be the voltage differential under load.

So if you have a neutral to earth fault, as the load increases it is more likely to trip. Also old RCD's seem to be affected by spikes, and also old consumer units don't have any surge protection devices.

Today we use RCBO's so any fault is only one one circuit, and also it means you can't have a problem with over design current of anything other than the isolator, and the SPD stops spikes, I would think there is some underlining problem with earth leakage, but with my own house the total earth leakage is getting to the point where it may trip a single RCD but spread out over 14 it is not enough to cause problems. And the 60 amp DNO fuse plus the output of the inverter is not over 100 amp, so the isolator's are within limits.

What would help is a picture of the consumer unit (CU) it may help understand the problem. Lid open of course, and also an over view.

 

[davelx]

And nothing that was done could change the power going through the consumer unit as all the DNO work would (should) have been on their side of the meter.

Uprating the DNO fuse will not make one iota of difference to the power being drawn by the installation.

Something else must be going on -please post photos of the installation and indicate what the DNO changed

 

[Adam_151]

This all seems a bit muddled up, as the proevious poster says, there is nothing illegal about a looped supply, generally undesirable but illegal no. No longer acceptable for new work but theres many out there that exist just fine, the DNOs are under an opligation to unloop them if you notify them about having an electric vehile charge point installed (possibly ASHP too)

The unlooping of the supply should have had no effect on the consdumer unit (generally provisio of there is a risk that things could get knocked or similar when in a tight understairs cupboard)

The loading you place on your supply is of course your own concern, not the DNOs as long as you stay within their limits, you appear to have been lead a little up the wrong path by them, the main switch sounds like an RCD (can we have a picture of the consumer unit?), and the issue you are having sounds like earth leakage issues within your installation, as an RCD does not go out on overcurrent, again the issues with earth leakage are your own to resolve, it is however possible that the operation of the RCD during works prior to disconnecting the power and when you tested the UPS could have free's off a previously sticking device (has it been tested with the test button every 3/6 months as per the label which should be there?)

 

[laneycakes]

I’m glad I posted here! It does seem my folks have been misled.

They were told that the loop was illegal now and as they had “discovered” it whilst fixing whatever the smart meter engineer had broken it had to be changed. There was no choice, it was a requirement.

There are no solar panels, no heat pump, no EV charger nor intent to install any.

I’ll get some pictures of the work and consumer unit next time I go round so you can see what they have.

It’s just worrying that the contractors who came out to check the cable work told my folks there was now too much power for the consumer unit. And it seems v strange that they have to go through this switching off of every trip before the master trip will switch back on. The engineers told them that they’d have to do that everytime they manually turned the master trip switch off until the consumer unit was replaced. The engineers were asked to leave a long “tail” on the wiring as it’s likely the consumer unit will need moving due to disabled adaptations taking place shortly.

I’ll get some pictures and post them as soon as I can. Thanks.

 

[ericmark]

I had in the old house some old fuse boxes, two RCD's in an adaptable box fed two Wylex fuse boxes where the fuses had been swapped to MCB's, it was fitted early 90's before consumer units came out, and I would every so often get a run of trips, and resetting one RCD could cause other one to trip, and often could not reset without turning off the MCB's.

I tested many times with my insulation tester and never did find a fault, it would then after tripping maybe 4 times in two weeks, run for 2 years without tripping. I blamed spikes on the supply, but never did find out what was wrong. The RCD's were likely from late 80's with no electronics, and were 4 module wide.

Today I can test leakage

it shows my whole consumer unit is leaking 8 mA, and this is spread across 14 RCBO's so I have only had a RCBO trip when the roof leaked, which is what it should do. I was happy to spend the extra and have all RCBO's so I did not get a repeat of problems with old house.

But the problems with the old house were due to having done it on the cheap, I should have ripped out the old fuse boxes and fitted a proper consumer unit, and the whole lot was well past its best by date. Had I owned the meter shown in the old house I may have found the problem, but trial and error is not the way to cure problems.

 

[cjcoffin]

t’s just worrying that the contractors who came out to check the cable work told my folks there was now too much power for the consumer unit. And it seems v strange that they have to go through this switching off of every trip before the master trip will switch back on. The engineers told them that they’d have to do that everytime they manually turned the master trip switch off until the consumer unit was replaced. The engineers were asked to leave a long “tail” on the wiring as it’s likely the consumer unit will need moving due to disabled adaptations taking place shortly.

Yes as others have said this is garbage, nothing has been done to increase the load, the fact that more power is now theorectically available has no bearing on it. If there is an earth leakage fault on one of the final circuits or they are a bit marginal then fitting a new consumer unit may make no difference at all.

Hopefully the ppl involved in the disabled adaptations will have more of a clue than the so-called "engineers" with whom you have had dealings so far. They ought to test the final circuits exhaustively before deciding whether to re-install the existing CU or fit a new one.

 

[laneycakes]

Ok here’s some pics:
consumer unit

Then this is the wiring alongside:

And then this is what they did when we asked for a “tail” to be left to allow the movement of the consumer unit into the adjoining room..

 

[Murdochcat]

What does the newer 40A breaker on the right do?

Updating the CU would make some sense, because at the moment if the main switch/rcd trips they lose everything. Modern units with RCBOs means that in the case of most faults only 1 circuit would trip

 

[ericmark]

Not sure why you have this but it is likely the length of the neutral tail why this problem has shown its self. Likely there has always been a small problem, but length of cable has made it worse.

But real problem is whole house on one type AC 30 mA RCD. Yes we have caravans and narrow boats on one RCD, but they are smaller than a house, and do have 12 volt lighting. Not got the up to date version of the regulations, but it has said the supply should be divided into circuits to

(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation

for years, we may have got away with it when using 100 mA RCD's but with 30 mA it is asking for problems.

I would guess there is a neutral to earth fault, easy for me to find, I have the tools, but for the normal house holder we would tell them to move items around between the two or more RCD's to try to work out what is causing the trip, but with only one RCD that is not possible.

Best answer is a new consumer unit with all RCBO's, but clearly there is a cost, so unless they can afford the change, then need to find the earth leakage, need to find it anyway really, but it will need a tool of some sort to find it. In the mean time, all one can do is unplug anything not in use.

I do not understand why this has been done? It just seems some one has too many henley blocks and wanted to use some up. And yet not an isolator in sight.

Wait for more replies, as I would not put up with a job like that.

 

[Harry Bloomfield]

I would hazard a guess, that it's an accumulation of leakages, tripping the RCD, and that it has always been a problem - except it has gone unnoticed because their has never been a need for the supply to be turned off before. Turning them back on, one at a time, simply works around the tripping issue.

All the OP can do is tollerate the problem, or install a new consumer unit, supporting individual RCBO's for each circuit. None of which is the DNO's problem. I do agree there ought to have been an isolator installed on those tails, but they have been over-generous in running those tails in readiness for a new, repositioned consumer unit.

Possibly the reason for the 'unlooping' of the supply, is because the neighbour who the supply is shared with, is getting an EV, or a ASHP system?

 

[flameport]

but there’s now too much power for that consumer unit to handle,

Not possible.

More likely is that the old supply was either TT or had an otherwise poor earth connection.
The new will be TNCS, and the significantly improved earth connection has revealed fault(s) which were always there but not noticed due to the high earth impedance.

is it now potentially unsafe?

It's not unsafe but it will certainly be inconvenient.
A fault to earth will result in everything being switched off, and if the fault remains switching on may not be possible at all.
However this has been the case since that consumer unit was installed decades ago.

The engineers were asked to leave a long “tail” on the wiring as it’s likely the consumer unit will need moving due to disabled adaptations taking place shortly.

That consumer unit will not be moved - it will be replaced with a new one. That work should also include a full test and inspection of the installation, with any defects fixed.

 

[ericmark]

It could also be no earth to TN-C-S I found this with parents house, likely used water main when built, but replaced with plastic.

 

[securespark]

That consumer unit will not be moved

It will if the customer requests it or the adaptations dictate it.