Lost power but NO RCBO tripped

[Kash]

Hey all,

First off, Merry Christmas to all

Right, so I have had a really weird thing happen earlier today. We lost power completely to the whole house, I assumed something tripped one of the RCBO's, so went downstairs to check the CU, and notice NOTHING was tripped off? However there was NO power to the house at all. At this point, I thought maybe external.

Just to make sure I switched off/on the main 100amp switch and everything came back on? No idea what happened.

Now I would have left it and not thought anything of it, however we have two CU. One in our outhouse and one in the main house.

What gave me a strange feeling was, as I went round to set the clock on the oven, microwave, I made my way to the outhouse, where I have some computer equipment running. I thought I would have to turn them on etc.. However I was surprised that these were still running - so I checked the "uptime" and they all said 32days (which was last time I rebooted those machines). So basically the Outhouse didn't lose power.

So it couldn't have been anything external which caused the power loss.

I have checked the tails to for the main house CU, nothing is loose. I am stumped as to what could have caused just one CU to lose power without tripping anything.

Everything is working find as it has been for the last year or so (since we refurbished the house). So I am curious as to what this could be ?

Any thoughts?

NOTE: I am not trying to solve the issue or "fix" anything since it is all working now. However curious what would cause this scenario.

 

[snowhead]

How old is the C.U that you turned Off/ On?

 

[Pete999]

Hey all,

First off, Merry Christmas to all

Right, so I have had a really weird thing happen earlier today. We lost power completely to the whole house, I assumed something tripped one of the RCBO's, so went downstairs to check the CU, and notice NOTHING was tripped off? However there was NO power to the house at all. At this point, I thought maybe external.

Just to make sure I switched off/on the main 100amp switch and everything came back on? No idea what happened.

Now I would have left it and not thought anything of it, however we have two CU. One in our outhouse and one in the main house.

What gave me a strange feeling was, as I went round to set the clock on the oven, microwave, I made my way to the outhouse, where I have some computer equipment running. I thought I would have to turn them on etc.. However I was surprised that these were still running - so I checked the "uptime" and they all said 32days (which was last time I rebooted those machines). So basically the Outhouse didn't lose power.

So it couldn't have been anything external which caused the power loss.

I have checked the tails to for the main house CU, nothing is loose. I am stumped as to what could have caused just one CU to lose power without tripping anything.

Everything is working find as it has been for the last year or so (since we refurbished the house). So I am curious as to what this could be ?

Any thoughts?

NOTE: I am not trying to solve the issue or "fix" anything since it is all working now. However curious what would cause this scenario.

Not nice to happen over the Hols Mate, difficult to diagnose from afar.

 

[telectrix]

child under age of 19 switched off main switch as a prank? perhaps his sister was in the shower??

 

[DPG]

Strange thing to happen. Something caused it - maybe even a faulty main switch. I would get it checked out by a qualified sparky. Faults like this can often result in things getting hot and melting if they aren't sorted.

 

[Wilko]

Hi - if I have understood correctly, you’ve eliminated the possibility of a supply outage, main fuse failure or a final circuit fault. That seems to leave the isolator or the adjacent cables in that Consumer Unit as prime suspects in this whodunit. I would check the cables are all nicely torqued as per @DPG post.

 

[Kash]

How old is the C.U that you turned Off/ On?

Consumer unit is less then a year old. Everything is brand new as part of refurbishment. All certified etc..
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Strange thing to happen. Something caused it - maybe even a faulty main switch. I would get it checked out by a qualified sparky. Faults like this can often result in things getting hot and melting if they aren't sorted.

that is my concern, but I’m more afraid this is intermittent and that nothing will go wrong for weeks and so sparky may not see the fault - or could a sparky test the switch to confirm it’sactually faulty? Ideally would like to know why it happened

Hi - if I have understood correctly, you’ve eliminated the possibility of a supply outage, main fuse failure or a final circuit fault. That seems to leave the isolator or the adjacent cables in that Consumer Unit as prime suspects in this whodunit. I would check the cables are all nicely torqued as per @DPG post.

Will just call in a sparky and pay the call out charge, seems to be the best option, as it’s not something obvious. Because I don’t believe anything is loose as it’s been running fine for month and now running fine again after switch off/on again.

 

[Pretty Mouth]

Can you post a photo or 2 of your consumer unit, showing the main switch that you switched off/on?

 

[Strima]

Is it a switch or an RCD?

 

[Kash]

Can you post a photo or 2 of your consumer unit, showing the main switch that you switched off/on?

I’ve attached one, I’ll take another one once I am home.
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Is it a switch or an RCD?

100amp isolator switch

the rest are all RCBO’s

 

[ipf]

Looks like that second (OK) supply isn't via the isolator...….tell you something?

 

[Kash]

Yep Roy Rogers has been about, if RR don't ring a bell think COWBOY

Why does the second supply “have” to be through the first supply.

when this was being installed the guy asked me if I wanted it separate so that neither affected each other etc... as you can see it’s split from the meter properly with two extra isolators. It was all installed by a certified installer and approved by building control.

my question wasn’t why the second didn’t turn off - that makes sense if it wasn’t an external issue, my question is why did the primary go off with nothing tripping.

 

[Vortigern]

Some switches switch off and don't appear to be in the off position. In order to re-energised the circuit you would have to switch right off then on which would reset the switch. That seems the most likely explanation. Which switch did you switch off. I hardly need to ask as if you had switched off the main isolator then your computers would have gone off so it must have been the wylex switch. So when certain switches go off they only look as if they are not fully up rather than fully down and as said you would have to pull them right down to reset. Did you feel the switch was a bit loosed when you switched it off?
EDIT: just seen you lates post above so maybe then....

 

[Pete999]

Hey all,

First off, Merry Christmas to all

Right, so I have had a really weird thing happen earlier today. We lost power completely to the whole house, I assumed something tripped one of the RCBO's, so went downstairs to check the CU, and notice NOTHING was tripped off? However there was NO power to the house at all. At this point, I thought maybe external.

Just to make sure I switched off/on the main 100amp switch and everything came back on? No idea what happened.

Now I would have left it and not thought anything of it, however we have two CU. One in our outhouse and one in the main house.

What gave me a strange feeling was, as I went round to set the clock on the oven, microwave, I made my way to the outhouse, where I have some computer equipment running. I thought I would have to turn them on etc.. However I was surprised that these were still running - so I checked the "uptime" and they all said 32days (which was last time I rebooted those machines). So basically the Outhouse didn't lose power.

So it couldn't have been anything external which caused the power loss.

I have checked the tails to for the main house CU, nothing is loose. I am stumped as to what could have caused just one CU to lose power without tripping anything.

Everything is working find as it has been for the last year or so (since we refurbished the house). So I am curious as to what this could be ?

Any thoughts?

NOTE: I am not trying to solve the issue or "fix" anything since it is all working now. However curious what would cause this scenario.

KASH where are you situated? could visit if not far from N/ton, Oh London to far

 

[Kash]

Some switches switch off and don't appear to be in the off position. In order to re-energised the circuit you would have to switch right off then on which would reset the switch. That seems the most likely explanation. Which switch did you switch off. I hardly need to ask as if you had switched off the main isolator then your computers would have gone off so it must have been the wylex switch. So when certain switches go off they only look as if they are not fully up rather than fully down and as said you would have to pull them right down to reset. Did you feel the switch was a bit loosed when you switched it off?
EDIT: just seen you lates post above so maybe then....

I switch off/on the main isolator inside the consumer unit, not the ones you can see in the picture. I’ll send a better picture

but what your saying does make it the most likely thing that happen, I didn’t know that main switches could trip
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KASH where are you situated? could visit if not far from N/ton, Oh London to far

Im in Ilford - east London

 

[ipf]

Why does the second supply “have” to be through the first supply.
It doesn't.
my question wasn’t why the second didn’t turn off - that makes sense if it wasn’t an external issue, my question is why did the primary go off with nothing tripping.

There's a supply fault....The switch you're messing with or something else prior to the CBs.... OR at that separate isolator. Heat does strange things, especially to copper it seems.....check for any....or signs of.

 

[Pete999]

I switch off/on the main isolator inside the consumer unit, not the ones you can see in the picture. I’ll send a better picture

but what your saying does make it the most likely thing that happen, I didn’t know that main switches could trip
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Im in Ilford - east London

PM me post code I'll see how far it is, will be just travel costs if it's close enough

 

[Kash]

There's a supply fault....The switch you're messing with or something else prior to the CBs.... OR at that separate isolator. Heat does strange things, especially to copper it seems.....check for any....or signs of.

when it happened I did check to see if cables were loose, nothing seemed loose and as I said it’s been working fine for a while.

If the main isolator in the CU did trip what would cause it to trip? And why didn’t the isolator before it trip.

from the main supply I have an isolator, then the tails go from there to the main CU, but even though nothing tripped I only flicked the isolator in the CU. So my question now is, what causes an isolator to trip, and why didn’t the isolator prior not trip also?
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PM me post code I'll see how far it is, will be just travel costs if it's close enough

Northampton is a long drive mate, I’m always going up to Leicester, don’t think it’s worth the journey but appreciate the offer.

 

[ipf]

They're isolators, just switches,...…... they don't auto trip.
Faulty switch or bad connection causing the break in supply.

 

[Pete999]

when it happened I did check to see if cables were loose, nothing seemed loose and as I said it’s been working fine for a while.

If the main isolator in the CU did trip what would cause it to trip? And why didn’t the isolator before it trip.

from the main supply I have an isolator, then the tails go from there to the main CU, but even though nothing tripped I only flicked the isolator in the CU. So my question now is, what causes an isolator to trip, and why didn’t the isolator prior not trip also?
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Northampton is a long drive mate, I’m always going up to Leicester, don’t think it’s worth the journey but appreciate the offer.

send your post code and I'll discuss with my Son, I'm all for helping out when I can s\despite what others may think, travel costs only my tome is free, or maybe a Maccy Dees on the way home

 

[Kash]

Oh just thought of another thing which will add further to the plot.

my nest smoke alarms

They're isolators, just switches,...…... they don't auto trip.

ok so that really confusing. If they don’t trip then I’m surprised a flick on and off made it work - and more concerning as well.
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send your post code and I'll discuss with my Son, I'm all for helping out when I can s\despite what others may think, travel costs only my tome is free, or maybe a Maccy Dees on the way home

Sent you a PM

 

[Pretty Mouth]

If the main isolator in the CU did trip what would cause it to trip? And why didn’t the isolator before it trip.

from the main supply I have an isolator, then the tails go from there to the main CU, but even though nothing tripped I only flicked the isolator in the CU. So my question now is, what causes an isolator to trip, and why didn’t the isolator prior not trip also?

Sometimes an RCD may be fitted as a main switch, and when some RCDs trip, the switch moves to a latched position, halfway between on and off. As per voltigern's post above, to reset you have to switch it to the off position, then on. I suspect this might have happened in your case.

Why the downstream RCBO didn't trip first we can't say for now, but a photo of your board showing all breakers may help us advise

 

[Vortigern]

If it is not the switch thing (main isolators don't trip unless they are RCD type) then it is quite likely a loose connection which if so should be attended to tout suite

 

[Kash]

ok so I am back home now, see photo attached of CU. The big main isolator on the right, is the ONLY switch i turned off/on.

The rest of them are as they were before.

External Socket we switch off when not being used, spare (emtpy), and Car charger is not connected either.

 

[static zap]

Christmas is a time for peak demands ,that will discover "Problem" connections... an expert will know several suspects.
(without disturbing other things unnecessarily)

likely a loose connection which if so should be attended to tout suite

 

[Kash]

Christmas is a time for peak demands ,that will discover "Problem" connections... an expert will know several suspects.
(without disturbing other things unnecessarily)

yeah I don’t want to be messing about with it. Will arrange electrician to come and have a look after new year

 

[Lister1987]

Probably barking up the wrong tree here but those Henley/connector blocks look odd, the wires coming out at least; outer 2 appear to go to the switch fuse, inner 2 to the isolator - would have thought it'd be 2 left, 2 right ,but then I remembered its line & neutral so should it not be a case of 1 & 3 to switch fuse (or isolator) and 2&4 to either the isolator (or switch fuse) as it stands you've got 1&4 used together at the switch fuse and 2&3 at the isolator.

As I say I'm probably wrong but it didn't look right to me.

 

[Kash]

Probably barking up the wrong tree here but those Henley/connector blocks look odd, the wires coming out at least; outer 2 appear to go to the switch fuse, inner 2 to the isolator - would have thought it'd be 2 left, 2 right ,but then I remembered its line & neutral so should it not be a case of 1 & 3 to switch fuse (or isolator) and 2&4 to either the isolator (or switch fuse) as it stands you've got 1&4 used together at the switch fuse and 2&3 at the isolator.

As I say I'm probably wrong but it didn't look right to me.

I think your confusing what is happening, there are two tails coming from the meter to the bottom of each Henly block - live/neutral. So I have a live henly and a neutral henly, then I have two tail coming out of the top of each henly - one live and one neutral goes to the main house Isolator the to the main cu and the and the others goto the outhouse isolator then off to the outhouse CU.

when the engineer was installing he was explaining all of this so I remember it quite well. I work in IT sector and have do infrastructure architecture for large data centres (Savvis, Level3, etc...) so am always fascinated with all this stuff.

 

[marconi]

Kash: I have a few friends who are policemen and detectives. I once asked why they seem to ask the same question over and over again. The reason is that it prompts or forces folk to think deeper and remember finer detail so when they do answer one more time it often adds to the earlier story/explanation/description as to what happened or what they did or saw or said or heard - etcetera. May I ask you then, in a similar vein to describe again - as if to a detective - what happened and what you did? Add some context too if you can eg: what loads were on at the time?

 

[Kash]

Kash: I have a few friends who are policemen and detectives. I once asked why they seem to ask the same question over and over again. The reason is that it prompts or forces folk to think deeper and remember finer detail so when they do answer one more time it often adds to the earlier story/explanation/description as to what happened or what they did or saw or said or heard - etcetera. May I ask you then, in a similar vein to describe again - as if to a detective - what happened and what you did? Add some context too if you can eg: what loads were on at the time?

LOL - sure ill go through the details step by step

1) Mrs turned the iron, but no light, so I thought the switch was off, went to turn it on, but it was on
2) Kids coming running in saying wifi isnt working
3) At this point I thought maybe electric tripped, I checked lights to if it was just sockets, but lights were not working either.
4) Went downstairs to check fuses, and noticed, nothing was tripped, even the mains was in the "on" position.
5) At this point I thought something outside must have happened. (I check around the kitchen, Oven time, microwave time were all off).
6) After about 10 mins, noticing that no one is outside asking each other if their electricity had gone, I thought why not flip the mains switch in the CU off/on - as soon as I did this everything came on.
7) I then went round setting the clocks on microwave, oven etc...
8) At this point, I went to go to the outhouse to check computer equipment, and noticed they were on? I was wondering, why they were on, I checked the uptime, and it said 32days.
9) Now I am really confused that the main house CU went off (without any signs of a trip) but he outhouse was running.

Thats everything

 

[davesparks]

Probably barking up the wrong tree here but those Henley/connector blocks look odd, the wires coming out at least; outer 2 appear to go to the switch fuse, inner 2 to the isolator - would have thought it'd be 2 left, 2 right ,but then I remembered its line & neutral so should it not be a case of 1 & 3 to switch fuse (or isolator) and 2&4 to either the isolator (or switch fuse) as it stands you've got 1&4 used together at the switch fuse and 2&3 at the isolator.

As I say I'm probably wrong but it didn't look right to me.

It doesn't matter, the service connector blocks are just commoning blocks and don't have any specific terminal designations. Whilst it would be nice for each one to be connected in logical order it doesn't make any difference functionally.

The bigger question as far as that isolator is concerned is why the smaller CU has been connected before the DP isolator? The whole point of having a seperate isolator fitted is to be able to isolate the whole installation from the incoming supply.

 

[Kash]

It doesn't matter, the service connector blocks are just commoning blocks and don't have any specific terminal designations. Whilst it would be nice for each one to be connected in logical order it doesn't make any difference functionally.

The bigger question as far as that isolator is concerned is why the smaller CU has been connected before the DP isolator? The whole point of having a seperate isolator fitted is to be able to isolate the whole installation from the incoming supply.

If you are talking about the small left hand side CU that’s just another isolator for the outhouse CU.

this wasdone so I could stop either CU supply independently. I believe it’s in a meta box because the armoured cabled to be installed properly needs a proper casing to connected onto via a gland.

 

[David Prosser]

You have computers that run for 32 days and no UPS ?

 

[Kash]

You have computers that run for 32 days and no UPS ?

Yes I have three servers and NAS. UPS are overrated for what they do and I don’t have mission critical stuff, I can rebuild the entire setup in an hour, it is all automated build and deploy.

 

[ipf]

The bigger question as far as that isolator is concerned is why the smaller CU has been connected before the DP isolator? The whole point of having a seperate isolator fitted is to be able to isolate the whole installation from the incoming supply.

Come on dave, think about it…….it's just another isolator doing the same thing for part of the installation...fused down.

 

[davesparks]

If you are talking about the small left hand side CU that’s just another isolator for the outhouse CU.

this wasdone so I could stop either CU supply independently. I believe it’s in a meta box because the armoured cabled to be installed properly needs a proper casing to connected onto via a gland.

Yes I'm talking about the small CU to the left which has been connected before the plastic supply isolator so that you have no single point of isolation for the entire installation, defeating the object of having the plastic isolator fitted in the first place.

You can isolate each CU via their main switch independantly without that isolator,
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Come on dave, think about it…….it's just another isolator doing the same thing for part of the installation...fused down.

I'm thinking about it and can't see it.
It's also not fused, that is just a wylex REC2 100A DP switch in a plastic box

 

[Kash]

Yes I'm talking about the small CU to the left which has been connected before the plastic supply isolator so that you have no single point of isolation for the entire installation, defeating the object of having the plastic isolator fitted in the first place.

You can isolate each CU via their main switch independantly without that isolator,
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I'm thinking about it and can't see it.
It's also not fused, that is just a wylex REC2 100A DP switch in a plastic box

??‍ Honestly don’t know it’s how it was

Yes I'm talking about the small CU to the left which has been connected before the plastic supply isolator so that you have no single point of isolation for the entire installation, defeating the object of having the plastic isolator fitted in the first place.

You can isolate each CU via their main switch independantly without that isolator,
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I'm thinking about it and can't see it.
It's also not fused, that is just a wylex REC2 100A DP switch in a plastic box

no idea mate, I mean I could switch both off and isolating both CU from any supply? The only time I think that would ever need to happen would of changing CU? Which fingers crossed would be never

 

[ipf]

I'm thinking about it and can't see it.
It's also not fused, that is just a wylex REC2 100A DP switch in a plastic box

That's feeding the main CU. Your 'small CU to the left' is isolation for the outhouse....fused, I'll wager.......and I'd sooner have that as isolation than a cheap plastic one.

 

[Kash]

That's feeding the main CU. Your 'small CU to the left' is isolation for the outhouse....fused, I'll wager.......and I'd sooner have that as isolation than a cheap plastic one.

Yep that one is fused I believe

 

[OnlQQker]

1) Mrs turned the iron, but no light, so I thought the switch was off, went to turn it on, but it was on You'll be surprised what they will do to get out of doing the housework
2) Kids coming running in saying wifi isnt working This is actually a great way of finding out how many kids are in the house

Not that I know much but have you tried the iron since?

 

[Kash]

1) Mrs turned the iron, but no light, so I thought the switch was off, went to turn it on, but it was on You'll be surprised what they will do to get out of doing the housework
2) Kids coming running in saying wifi isnt working This is actually a great way of finding out how many kids are in the house

Not that I know much but have you tried the iron since?

Lol - just after I wrote that post ?

 

[OnlQQker]

What else was running? obviously the wifi and the computers outside, tumble drier, washing machine, dishwasher, undersink heaters?

I'm with the other poster and turning it into a full on interrogation

 

[static zap]

Do you have Gas central heating ?
( is it a normal family situation , or have a few Xmas visitors taken fan heaters into the loft ! )
Your meter will probably have "Clues" of any usage spikes !

 

[Kash]

What else was running? obviously the wifi and the computers outside, tumble drier, washing machine, dishwasher, undersink heaters?

I'm with the other poster and turning it into a full on interrogation

? just thought all this information was required ?
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Do you have Gas central heating ?
( is it a normal family situation , or have a few Xmas visitors taken fan heaters into the loft ! )
Your meter will probably have "Clues" of any usage spikes !

Central heating was running (to be honest have it running 24/7 currently)

Just my family no guest it was around 10am so too early for anyone to pop round. Absolutely no electric heaters.

In terms of electric usage nothing out of the ordinary

 

[marconi]

Torque Talk: Electrical Connections and Torque Requirements - https://www.e-hazard.com/blog/electrical-connections-and-torque-requirements/

My money is on the cause cited by DPG and Wilko - under torqued screws making the connections on the line and neutral supply between the Henley and the busbars of the domestic CU. This coupled with a phenomenon know as wetting current - the minimum current necessary to maintain a conductive path between touching metal surfaces.

One might think there is plenty of surface contact between say a 16 or 25 mm2 cables and the inner connection surfaces. But when one considers the cross-sectional geometry of the stranded cable and how it touches the inside of the connection it is often the case that there is insufficient conducting surface area and what is touching has little mechanical pressure. This allows air to to oxidise the touching surfaces over time further reducing the net conductance of the connection and promoting problems due to a raised minimum wetting current.

The way to avoid this problem is to make clean connections and use the proper torque screwdriver to tighten up the screws/bolts. And to check the torque a little while later after the copper has deformed/flowed from the pressure on it after the first torque down. The manufacturer details the required torque. And then to have a periodic check on them.

The almost universal absence of cable clamps of meter tails means all the stress of cable movement is borne at the terminals which undermines the goodness of the original connection even if torqued correctly. (This was a NICEIC pick up point for the electrician who used our home rewire as his exhibition installation - the tails are now clamped and not left floating in the air.)

See page 48 of 52:
https://www.wylexreasons.co.uk/Content/pdf/Wylex DCP catalogue Feb 2018.pdf

For some other makes:

http://www.elecsa.co.uk/documents/c...l-downloads/manufacturer-torque-settings.aspx

Wilko can say more about his Gucchi torque screwdriver which is perfect for most CUs and ideal Christmas present to oneself.

 

[marconi]

Ergo Plus Torque Screwdriver Set - 9 Piece - https://www.tlc-direct.co.uk/Products/DR65372.html?source=adwords&ad_position=&ad_id=315107931576&placement=&kw=&network=u&matchtype=&ad_type=&product_id=DR65372&product_partition_id=576185600822&campaign=shopping&version=finalurl_v3&gclid=Cj0KCQiAl5zwBRCTARIsAIrukdNr3GR5w76L_VcZYassrLu9-KUjMesu92zU2QX-8vQLgPNvgQr8O2waAurUEALw_wcB

1-5 Nm torque.

 

[Kash]

Ergo Plus Torque Screwdriver Set - 9 Piece - https://www.tlc-direct.co.uk/Products/DR65372.html?source=adwords&ad_position=&ad_id=315107931576&placement=&kw=&network=u&matchtype=&ad_type=&product_id=DR65372&product_partition_id=576185600822&campaign=shopping&version=finalurl_v3&gclid=Cj0KCQiAl5zwBRCTARIsAIrukdNr3GR5w76L_VcZYassrLu9-KUjMesu92zU2QX-8vQLgPNvgQr8O2waAurUEALw_wcB

1-5 Nm torque.

That’s some expensive screwdrivers

 

[Pete999]

That’s some expensive screwdrivers

Yep, and no good for Aluminium conductors either.

 

[davesparks]

Yep, and no good for Aluminium conductors either.

Why not? I thought aluminium connections required the correct torque?

 

[ipf]

Yep, and no good for Aluminium conductors either.

…..are we on the correct thread, Pete?
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Why not? I thought aluminium connections required the correct torque?

That switch fuse is OK, though.