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.

 

[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 ?
[automerge]1577493482[/automerge]

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?
[automerge]1577573868[/automerge]

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

That switch fuse is OK, though.

 

[Pete999]

…..are we on the correct thread, Pete?
[automerge]1577573868[/automerge]

That switch fuse is OK, though.

Was responding to the expensive screwdriver thread, did make me wonder though, lol

 

[smarty1972]

Did you get this problem sorted? I would say that the main switch is being overloaded by the loads of the various circuits you have, rcbo will trip on either neutral/earth fault or overload of specific circuit but main switch will add all loads together. Does it happen more when the ev is charging?

 

[Kash]

Hineslty, I just got busy with other stuff (as this was complete renovation), I totally forgot about it. Been on my list but never got round to it.

I haven’t had any issues since and I haven’t done anything. So finger crossed ?

Did you get this problem sorted? I would say that the main switch is being overloaded by the loads of the various circuits you have, rcbo will trip on either neutral/earth fault or overload of specific circuit but main switch will add all loads together. Does it happen more when the ev is charging?