20A Radial for Fridge and Dryer

[Yanni]

I am thinking of splitting the house ring as it serves the whole house and create a new ring for the kitchen.
I am also thinking of creating a radial for a Samsung Fridge freezer and a dryer.
Do you think a B20 RCBO on a 2.5mm cable will serve both these appliances ok?

 

[EFLImpudence]

Yes, assuming the cable does not run surrounded by thermal insulation.

What are the ratings of the appliances?

 

[ericmark]

The whole idea of the ring final is to have lighter cable (saving on copper) which can take a total area of around 100 meters², and is supplied by a 30 amp fuse, latter a 32 amp MCB or RCBO, it has an advantage in latter years that the fused plug has also allowed the use of smaller appliance leads, it was originally permitted a 4% volt drop, seem to remember this allowed 85 meters of cable, but latter this was changed to 5% for sockets (106 meters) and 3% for lighting.

We consider the maximum load at centre to be 20 amps, and the remaining 12 amps to be even spread, so design current for circuit Ib is considered as 26 amps. This equates to 0.59Ω drop in the line - neutral impedance or 106 meters of 2.5 mm² cable.

With a radial also using 2.5 mm² cable with a 20 amp MCB/RCBO the total length of cable drops to 32 meters, this equates to 0.79Ω drop in the line - neutral impedance.

Clearly, 106/2 does not equal 32, so when splitting a ring one has to be careful that the permitted volt drop is not exceeded.

What one can do depends on the house size, the splitting of the ring final side to side in the main results in less of a volt drop to splitting up/down, it also means should one ring final fail, no need to run extension leads up downstairs, so that is the better split, but when the twin RCD consumer unit came out, to ensure the lights and sockets were not on the same RCD, we moved to upper and lower ring final so lights and sockets in any room are not on the same RCD.

However, in days gone by, it was common to have the whole house on a 100 mA RCD, it is down to how one interprets what BS7671 says. Nothing is written in stone, the competent person has to decide, still the same today where caravans often are supplied from on 30 mA RCD.

So what you propose may be a good idea, but you need to decide if it will suit that home, there is no one size fits all, my kitchen has 3 supplies, 32 amp to cooker, 32 amp to that side of house ring final, and 16 amp to a pair of double RCD sockets for the freezers' battery back from the solar battery. So 2 RCD's and 2 RCBO's feed the kitchen.

I don't have lights battery backed, as should I have a power cut, don't want over 100 watt of lighting load for living room alone. I have done my risk assessment, you need to do yours.

 

[Yanni]

The run is less than 8m from CU to the socket. As far as the ratings are concerned the dryer is a Bosch with heat pump so it doesn't consume as much and I have not decided on a fridge yet, just a standard fridge freezer, single one as there is no room for a double one.

This is a 2 bed bungalow that has all the sockets in the house on a single 32A RCBO so I need to do something about it .

The main reason I want the radial for the fridge I think I still have nightmares from one of my African tenants that he used to defrost meat every week and the juices would drop on the fridge's door switch tripping half of the house!

 

[Murdochcat]

If this is a property you let out then you’ll need certification for any changes

 

[Yanni]

No this is my house!

 

[ericmark]

If this is a property you let out then you’ll need certification for any changes

All property should have a minor works or installation certificate raised for any electrical work, it does not matter if rented or owner occupied, as to if a compliance or completion certificate is required, is also the same be it rented or owner occupied, the only time when rental and owner occupied are different, is after an EICR has been completed. And it is very poorly written, so to be sure would be down to case law.

There is nothing to stop me from filling in my own minor works or installation certificate, and there is nothing to stop me submitting these to the LABC, as to if the LABC accepts them is up to them, and as to the cost to register work yes it may be cheaper to have a scheme member do the work.

Manchester the last time I looked is in England, so the special location only includes the bathroom, and since the circuit already exists, it is not a new circuit. Yes, it depends on how you look at the English, this is not an electrical question but an English language one. But to me if any part of the circuit has existed in the past, it is not a new circuit, just a modified one.

As said many times, it is up to the courts to decide, and unless there is something wrong with the work, it is unlikely to go to court, even if there is, as long as it is corrected, then again unlikely to go to court, so we are unlikely to see case law generated about this.

 

[EFLImpudence]

Manchester the last time I looked is in England, so the special location only includes the bathroom,

Only within the zones in a bathroom.

 

[ericmark]

Only within the zones in a bathroom.

Sorry yes, I forget living in Wales, so easy to forget the English rules, Oh to drive at 30 in a built-up area.

 

[crystal ball]

Sorry yes, I forget living in Wales, so easy to forget the English rules, Oh to drive at 30 in a built-up area.

20 MPH signs are popping up in many towns in England

 

[ericmark]

I was looking at the notice for road works, which stated there would be a 30 MPH speed limit around the road works, but they are in a 20 MPH area. To be frank 10 MPH would be more appropriate, but it does raise questions as to the legal status of both 20 and 30 MPH speed limits, with repeater signs being missing in both cases.

It is the same with electric installation, what is recommended, and what is law, tend to get all muddled up. But I feel I would rather not fight a test case.

So I am the old foggy who is doing 20 MPH in a 30 limit, as not sure what the limit is.

 

[Taylortwocities]

20 MPH signs are popping up in many towns in England

Yes, and Cruz Beckham has been banned after being caught out!

Cruz Beckham loses driving licence for speeding just two years after passing test

Cruz must re-take his driving tests after receiving two speeding penalties less than two years after passing

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