Is this normal?

[ray99]

Was changing a socket in the kitchen tonight as the plug had become hard to insert for some reason. The consumer unit in the garage had two trip switches marked sockets so tried one and tested the kettle and toaster. Neither worked so thought it was safe to proceed. Was just about to slacken the screws holding the cables when I heard the fridge start up. Further investigation revealed that the sockets on the left of the kitchen were dead and the sockets on the right were still live????
I always thought the split was downstairs and upstairs or if three trip switches marked sockets in the consumer unit it was upstairs, downstairs and kitchen.
House is ten years old.

Recently noticed that the lights labelled as up and down were actually down and up.

 

[PrenticeBoyofDerry]

As Tom Jones would say "It's not unusual"
There is nothing to say that all the sockets in one room should be on the same circuit. It would be nice if the CU was marked up correctly though.
But what should be done is safe isolation procedures.
The first thing you do is identify the circuit and prove it is dead!
That's the circuit/socket you are working on not the kettle/WM/toaster/TV/fridge etc..
The one you are going to be poking about in!

 

[Paul_C]

The upstairs/downstairs or upstairs/downstairs/kitchen split is very common, but far from the only arrangement in use. I've argued for years that these arrangements are actually far from ideal, and a front/back split would in many ways be better than an up/down split in the typical house. Ditto for splitting the sockets in the kitchen between more than one circuit, since it's the place with the generally highest load.

 

[ericmark]

My sisters house was split side to side means less cable so better loop impedance. Although each room has same braker.

My house two consumer units each with a MCB for sockets and each room has mixture so if one the the RCD's feeding the CU trips there is still a supply to that room.

Although in my case it was one CU as standard and another with all the extras and was not installed by builder.

In theory each socket should be marked as to which MCB and CU but I have never bothered. As a result in my house it could be said as not complying!

Easy to mark up-stairs and down-stairs or North and South if side to side on MCB but with mixture it means labels on every socket. I would use three phase marking dots and have a red and blue dot showing which MCB. When I get around to it.

 

[ericmark]

The upstairs/downstairs or upstairs/downstairs/kitchen split is very common, but far from the only arrangement in use. I've argued for years that these arrangements are actually far from ideal, and a front/back split would in many ways be better than an up/down split in the typical house. Ditto for splitting the sockets in the kitchen between more than one circuit, since it's the place with the generally highest load.

I would agree it would make sense for a kitchen to have multi-MCB's and with the practice of having grid switches 20A supplies to grid switch then socket does mean you can't exceed the switch rating even with double sockets. And also fridge could be on non RCD supply (Assuming Ali-tube cable).

It is also common where an immersion heater, cooker, or other supply is no longer used to fit a 13A socket to identify live cable. So yes quite common.

 

[Paul_C]

A front/back, left/right etc. split also has the advantage that if one circuit needs to be turned off for work, or has to stay off due to a fault, there will be other sockets on the same floor from which extensions can be run without having to trail up or down the stairs. The same goes for the lights; with the up/down split if one circuit is out, you lose all the lights on the whole floor.

 

[ray99]

Thanks for the replies. Can see the sense in not having it wired up the way I was expecting. Would normally have tested the socket with a Fluke meter but that is at work (vehicle technician) unless I bring it home specially.

 

[Paul_C]

The lesson you've learned is never to assume! Always check that the piece of equipment you're about to work on has indeed been isolated by the switch or circuit-breaker you think has isolated it.

 

[Guitarguy]

It could of been worse- my house has two ring mains for the sockets, one for downstairs and one for upstairs. I was changing a socket upstairs and I turned off the breaker for upstairs and unscrewed the socket followed by the terminals and pulled the socket free leaving two reds, two blacks and two earths all lined up next to eachother but not touching. I went to grab the live and neutral to set them and got a massive belt! Turns out this is the only socket upstairs thats fed from the downstairs ring. What a dozy idea but it's my fault I was wrong and assumed (!) that it would be dead considering the other sockets were dead upstairs!

 

[Paul_C]

What a dozy idea but it's my fault I was wrong and assumed (!) that it would be dead considering the other sockets were dead upstairs!

Hence why one should never assume that something is dead. Fortunately, you didn't end up dead, but assuming could quite easily result in that.

 

[Guitarguy]

What a dozy idea but it's my fault I was wrong and assumed (!) that it would be dead considering the other sockets were dead upstairs!

Hence why one should never assume that something is dead. Fortunately, you didn't end up dead, but assuming could quite easily result in that.

Yes and what made me feel even more stupid is that i'm a cable jointer and assume is one of the most frowned upon words about in our company!

 

[securespark]

Yup!


It makes an ASS out of U and ME.

 

[ericmark]

I have argued about normal practice many times with my son. I have said how to do something would work out better and he has replied it's not normal practice and some one may get injured when they assume normal practice.

This leaves the question should one refrain from doing something in case some daft guy does not follow the isolation procedure? Do we assume that an electrician following one will follow the best practice advice or do we allow for the fact he may do something wrong?

If the latter where do we stop?

Although I have said many times one should always check I did when installing a water pipe to fridge/freezer put a hack saw blade through the switch wires for the lights which ran horizontal, which is permitted but was not expected.

I was going to say lucky I have RCD protection on all circuits but really nothing to do with luck. Before the government to protect people introduced Part P I fitted a box with two RCD's one feeding each consumer unit to protect my family, in particular my son who was a Radio Ham at that time being just 14. Today of course I would not be permitted to do this under Part P, but all those years ago back in late 80's I was allowed to protect myself and family. Today I would have to pay for some one else to do the work so likely it would not get done.

It does however make one slightly complacent, and one maybe does not take the care one should, looking for cables before starting on non electrical work.