Power blew - outside switch

JReacher1

I plugged a nintendo switch in yesterday to a four way extension cable and it made a bang, flashed and then blew the power in my house (6 year old new build).  Went to check the circuit breaker and it had tripped the switch.  Turned everything back on and still no power.  After a good hour of messing around and considering whether to phone an electrician I decided to check the meter outside.  Below the meter was a box with a switch and this had tripped to off.  When I flipped this back on all power came back on and it seems fine now.

I've never seen this before in a house (only been here 12 months) but if this sort of set up normal? 

I thought the circuit breaker would have handled the power short,

Section62

JReacher1 said:

I plugged a nintendo switch in yesterday to a four way extension cable and it made a bang, flashed and then blew the power in my house (6 year old new build).  Went to check the circuit breaker and it had tripped the switch.  Turned everything back on and still no power.  After a good hour of messing around and considering whether to phone an electrician I decided to check the meter outside.  Below the meter was a box with a switch and this had tripped to off.  When I flipped this back on all power came back on and it seems fine now.

I've never seen this before in a house (only been here 12 months) but if this sort of set up normal? 

I thought the circuit breaker would have handled the power short,

It depends on the type of fault and exactly which protection devices trip.

But, for example, if the fault is a short circuit then all the protective devices going back to the incoming mains will 'see' more or less the same fault current.  Which of the devices 'trip' will depend on their characteristics and the nature of the fault.  If the fault current is high enough for long enough then it could be possible for all the devices to trip, although in practice it could be anything from one to all.

In theory circuits are supposed to be designed with 'discrimination', so only the first upstream device should 'trip', but in the domestic setting whether this is achieved or not seems to be somewhat random in my experience.

AFAIK your setup is normal, albeit annoying that the whole house can be tripped out by a 'minor' fault on one circuit.

JReacher1

Thanks for that much appreciated. My last house was a Victorian terrace with an old fuse box and never had a problem with the electrics.  In my new house with the up to date electrics the power has tripped four times now! Previous three were caused by a leak on the boiler!

Bendy_House

JReacher1 said:

 In my new house with the up to date electrics the power has tripped four times now! Previous three were caused by a leak on the boiler!

It's working well then
In your previous house, your boiler fault would have likely run on without you being aware.

Is your meter 'smart'? It's a new one to me to have a switch located there - it was usually a main fuse (80 or 100A?), Which you would never expect to blow!

Any chance of a photo of this switch, please?

Section62

Bendy_House said:

JReacher1 said:

 In my new house with the up to date electrics the power has tripped four times now! Previous three were caused by a leak on the boiler!

It's working well then
In your previous house, your boiler fault would have likely run on without you being aware.

Is your meter 'smart'? It's a new one to me to have a switch located there - it was usually a main fuse (80 or 100A?), Which you would never expect to blow!

Any chance of a photo of this switch, please?

I don't know if everyone is doing it, but I've seen a lot of relatively recent installs where the electricity co has added a 'breaker' between the meter and the customer's consumer unit. It doesn't replace the main fuse, which is still there to protect the meter.

I haven't checked, but assumed this was a resurrection/extension of the policy some of the old 'boards' had of providing an isolator between meter and CU (by default or on request) which would allow isolation of the supply so an electician could work on the CU without needing the 'board' to come out and pull the main fuse (which itself now seems to be a far more complicated operation than it used to be).

JReacher1

Here you go. This is a photo of the switch. 

Section62

JReacher1 said:

Here you go. This is a photo of the switch. 

Is your consumer unit close to where the meter is, or is there some distance between them?

JReacher1

Consumer unit is inside the house in the downstairs toilet. The meter is outside the house. 

Section62

JReacher1 said:

Consumer unit is inside the house in the downstairs toilet. The meter is outside the house. 

You've got both RCD and MCB protection there.  I wondered whether it was because the meter was some distance from the consumer unit and therefore someone had decided the meter tails needed additional protection - some DNO's require(d) this if they judged the meter tails to be excessively long (e.g. 3 metres is/was one measure used.)

Protection of the meter tails is now treated more seriously than it has been in the past, so an arrangement like yours will probably become more common.

Albeit annoying if the 'outside' trip goes, and you don't know you've got one.

JReacher1

Much appreciated. Thank you for your help with this! Makes me feel better

Risteard

Section62 said:

JReacher1 said:

I plugged a nintendo switch in yesterday to a four way extension cable and it made a bang, flashed and then blew the power in my house (6 year old new build).  Went to check the circuit breaker and it had tripped the switch.  Turned everything back on and still no power.  After a good hour of messing around and considering whether to phone an electrician I decided to check the meter outside.  Below the meter was a box with a switch and this had tripped to off.  When I flipped this back on all power came back on and it seems fine now.

I've never seen this before in a house (only been here 12 months) but if this sort of set up normal? 

I thought the circuit breaker would have handled the power short,

It depends on the type of fault and exactly which protection devices trip.

But, for example, if the fault is a short circuit then all the protective devices going back to the incoming mains will 'see' more or less the same fault current.  Which of the devices 'trip' will depend on their characteristics and the nature of the fault.  If the fault current is high enough for long enough then it could be possible for all the devices to trip, although in practice it could be anything from one to all.

In theory circuits are supposed to be designed with 'discrimination', so only the first upstream device should 'trip', but in the domestic setting whether this is achieved or not seems to be somewhat random in my experience.

AFAIK your setup is normal, albeit annoying that the whole house can be tripped out by a 'minor' fault on one circuit.

Selectivity (as discrimination is now called) is only a requirement where there is a safety issue with upstream devices operating, although it's might of course be desirable. It can still be difficult and expensive to achieve under all circumstances, and therefore partial rather than full selectivity is more usual.