Replacing consumer unit

[tigerdraws]

Hi.
Lately in my family home the trip-switch for the 13amp plugs keeps tripping when very little load is applied. For example if the washing machine, tumble dryer, electric heater and a few computers are running and you boil the kettle the switch trips. No wiring changes have occurred lately and it's doing it more and more. I have been informed that old MCBs will wear out over time and slip off with increasing regularity.

I have decided therefore to install a new split-load consumer unit. I have done some research but I would really like any handy advice going.

For instance, I am concerned that the gnarly old wiring installed in the 70s (and a bit clumsily at that) will be impossible to adapt to a new size/shape of consumer unit. I was wondering if it was common practice to route old wiring into some sort of junction box to enable only nice spanking new wiring to enter the consumer box???

If this were possible/advisable the prospect of doing it myself will seem that much more attainable.

Any hints or advice on this or other points would be MOST welcome!!
Thanks in advance,

TOny

 

[Spark123]

It sound to me like you are putting too much load on that circuit, if you want to run everything at once you need more socket circuits to spread the load. What exactly is tripping, is it an MCB?

 

[Maxxy]

Hi.
For example if the washing machine, tumble dryer, electric heater and a few computers are running and you boil the kettle the switch trips. No wiring changes have occurred lately and it's doing it more and more. I have been informed that old MCBs will wear out over time and slip off with increasing regularity.
TOny

Kettle uses around 10 amps, heaters probably close to that. No idea what the washing machine or tumble dryer use, but im guessing your over the 32a mark like Spark123 said. Does it run off a 32 amp fuse, or is it a 20, or something else as its old?

Regarding the changing of the consumer unit, i aksed a similar question recently. You can do it yourself if you get LABC (local are building control) involved right from the start (before you even touch a wire). If your not an electrician, they may ask you to get one in to do a periodic inspection report first, to check the circuits and cables are all fine. Be aware this may lead to you having to rewire your entire house.

Best bet i'd say is ditch the electric heater if you can, do your washing late at night, or just dont have it all on at once.

 

[Adam_151]

1) MCBs can wear out (particulaly if they have been overloaded often), swapping a breaker out is a relativly painless task, however...

2) as spark123 says, it does sound like you are overloading the circuit (which links back to the bracketed part of item 1...) splitting it into multiple circuits would be the ideal solution

3) what do you think is the problem with the old wireing? if its just that its not long enough, then most electricians will crimp extensions on inside the CU, other solutions involve DIN mounter terminals in a separate enclosure, or replacing the lengths of cable nearest the DB, do you have other issues to consider, like imperial (stranded) sizing or possibly metric with undersized rfc CPCs, and if its not been all done particulaly well, could be worth considering a re-wire

4) Changing a CU is not something a DIY person should consider lightly, there is more to it than you probably think, though it is not beyond the capabilities of someone who researches what they are doing, but it might be as well to get a few quotes in, also bear in mind that what you plan to do now comes under the building regulations and is a type of work that should be notified to the buildings dept. at the local council.

 

[Adam_151]

Hi.
For example if the washing machine, tumble dryer, electric heater and a few computers are running and you boil the kettle the switch trips. No wiring changes have occurred lately and it's doing it more and more. I have been informed that old MCBs will wear out over time and slip off with increasing regularity.
TOny

Kettle uses around 10 amps, heaters probably close to that. No idea what the washing machine or tumble dryer use, but im guessing your over the 32a mark like Spark123 said. Does it run off a 32 amp fuse, or is it a 20, or something else as its old?

Kettle: anywhere from 8-13A, heaters about the same, washing machine 1-10A depending on part of the cycle, tumble drier: 8-10A (continiously)

So you have a possible 23A continuous load and at times it might be intermittantantly taking another 20A or slow, because of tripping characterisics a breaker will probably tolleratue this due to the non-sustained load, but i'll probably start to weaken the breaker resulting in it being less 'tolerant'

So the fact that the breaker is tripping out more than it used to is a syptom of the fault (often overload circuit) rather than a fault in its own right, you know what it is right to fix ....

 

[Steve]

. . . when very little load is applied. For example if the washing machine, tumble dryer, electric heater and a few computers are running and you boil the kettle the switch trips.

The items I have highlighted use considerable amounts of electricity. It is not "very little load". You are overloading the circuit. Work out how many amps each appliance is drawing. IF each appliance there uses 13 amps (IMO, not unreasonable for those listed) you are putting 52 amps on the circuit. And even if each appliance is 10 amps, thats 40 amps total.

My definition of "very little load" is a TV and a PC, perhaps a table lamp. Total load maybe 3 amps. I would be very worried if the breaker was tripping then. You, my friend, have a HUGE load.

And fixed electric heaters nowadays are frequently wired on a seperate circuit, for the reasons you have highlighted in this thread. Some people even wire a seperate circuit for their large white kitchen appliances, to avoid overloading the socket circuit. Most homes at least have a seperate circuit for the kitchen.

 

[tigerdraws]

HI everyone- thanks for the flood of responses.

Crafty, with regards to "very little load" your point is taken. I edited my post and accidently left that in. True, it is not a "very little load". Incidently the fuse is 30amp.

What puzzled me was that it never used to trip but your posts seem to make a reasonable point- a regularly pushed or overloaded circuit weakening the breaker over time sounds plausible.

What I didn't mention, but should have, is the main motivating force behind my deciding to upgrade the CU!!! The trip switches are a brand called Lupus and they have recently had their BS no. removed. They can no longer be bought or fitted legally.

If this wasn't the case I would have had no hesitation in splitting the plug sockets over two breakers- one upstairs, one down. Unfortunately this cheaper option is now impossible

All your feedback, past and future is greatly, greatly appreciated.
Tony