16A MCB radial circuit supplying all sockets

[two5ey]

Hi all, I was hoping for some advice. All the sockets in my house (3 bedroom terrace) are wired in a single radial circuit to a 16A MCB on 2.5mm cable. I was wondering was it possible to upgrade the MCB to 20A, as when using alot of appliances at the same time in the kitchen the MCB is tripping.

Is there any particular reason why a 16A may have been fitted over a 20A. I have a magnuss consumer unit.

At some point in the future when funds are a bit more readily available will try and get a rewire as the circuit is obviously overloaded. However would changing the MCB be safe as an interim measure? Will the extra 4A make much difference how easily the circuit trips?

 

[MalcofArabia]

The chances are your cable could take a 20amp protection device it really would depend on the length of runs and how it is installed.

Then after changing that device you will have to carry out certain tests to make sure that the protection device will operate in the desired time, this is called a Zs test.

You haven't said if you have a RCD as additional protection. If you do have a 30mA RCD then the Zs will not be so critical.

You would also have to certificate the alteration to your circuit as well. So all in all it's not that straight forward a job. IMO I would call in an Electrician to help you with this, it would not be overly expensive for him to ascertain the best way for you to go.

 

[two5ey]

Thanks for the reply! Yes there is a 30mA RCD on the consumer unit as well. Well it's labelled a "RCCB" but I am presuming this is the same thing your on about?

 

[Chri5]

Even at 20 amo you are unlikely to stop demand being higher than the fuse rating.

A single radial in a 3 bed house just won't cover the demands of 2010.

Normal standards are 3 rings based on kitchen, ground and 1st floor, although 4mm radials to all 3 areas is an alternative to the ring design.

If you walk around and count up in watts the potential demand of every item and appliance on the radial and divide that by 230v you will see why the fuse goes.

Be brutal and 'imagine' the kettle, microwave, tumble drier, hair drier, dish washer and iron are all on at once. If the above was all on it would be about 8000w / 230v = 33 amps.

I would start thinking about getting something done, it's not dangerous- but constant overload will hasten wear. Short stop job would be to split the radial and add in a new cu feed to the split point of the radial and then on test have 2 x 16 or 20 amp radial circuits,

 

[ban-all-sheds]

You haven't said if you have a RCD as additional protection. If you do have a 30mA RCD then the Zs will not be so critical.

An RCD should not be viewed as a good solution to a problem of too high a fault loop impedance.