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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Flat rewire https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1102371994 Message started by Chaddy on Dec 6^th, 2004, 10:26pm

Title: Flat rewire
Post by Chaddy on Dec 6^th, 2004, 10:26pm

Hi, i'm in the process of renovating a flat for a customer.
Part of the job entails replacing the consumer unit and rewiring completely.
Couple of questions,
1. Should i run a radial or ring to the kitchen sockets?And would 20 amp mcb be correct?
2. What size MCB should i fit for the combi boiler?
3. What size MCB should i fit for the cooker?

Also can you give me an idea of what it would cost to rewire a 2 bedroom flat including the following?...
Run new cables for
Shower, new socket ring main, lighting ring, cooker, boiler, kitchen sockets and fit new CU??
OK so it was more than a couple of questions!!!!
Thanks in advance for any help,
Cheers
Ken

Title: Re: Flat rewire
Post by The_Trician on Dec 6^th, 2004, 11:02pm

1. Ring for Kirchen sockets
2.3A or 6A for a combi-boiler/stat/programmer.
3.What power rating (in KW) is the cooker?

How much to rewire a flat? Around £1800.

TT

Title: Re: Flat rewire
Post by sparkyjonny on Dec 7^th, 2004, 12:35am

1. I'd install a radial - beter power distribution. 20A for 2.5mm cable, 32A for 4mm cable (you might find 4mm tricky to terminate in single-gang accessories - use 35mm deep boxes). Why do you favour rings, and their hot-spots, TT?

Title: Re: Flat rewire
Post by The_Trician on Dec 7^th, 2004, 12:41pm

Because Radials tend to get added onto, then the arguement goes 'But the current is limited by the 20A mcb'.

Yeah, until such a large number of sockets have been daisy-chained onto the radial, and so many more appliances have been plugged in to these sockets that the 20A mcb keeps tripping, so what do they do then?

Uprate the 20A to a 32A to stop the tripping problem, and then what do you have?

An open-ended Ring.

Stick a Ring in, the cables'll handle any overload much better.

TT

Title: Re: Flat rewire
Post by L.Spark on Dec 7^th, 2004, 12:44pm

Don't know why this even get's discussed, both have there advantages and disadvantages.

The rings only get a bad name by people who shouldnt be installing them in the first place, and the people that don't know what there doing, the same sort of people that give good tradesmen a bad name.

Title: Re: Flat rewire
Post by sparkyjonny on Dec 7^th, 2004, 7:00pm

What don't you like about 4mm radials then instead TT?

LS - what's your reasoning? Surely the fact that there is no danger of wiring a spur off a spur as there is on rings is a great advantage? You can isolate branches if required, for a room, or using a timer switch. Why bother running a further cable to complete a ring, especially in a single location such as a kitchen or garage with a dedicated radial.

The only possible disadvantages I can see is when people don't like terminating 4mm, and the risk of a DIYer branching off with 2.5mm.

Jon (A die-hard radial fan!) :D :D

Title: Re: Flat rewire
Post by Lectrician on Dec 7^th, 2004, 7:29pm

Rings will die soon........I bet money on that........and, to be honest, I wont miss them. I am a radial fan, and install them more than rings.

The only time a ring is any good is when it is a true 'ring main' ringing substations and distribution kit - then servicing becomes easier.

Title: Re: Flat rewire
Post by plugwash on Dec 7^th, 2004, 7:33pm

the ring was designed essentially to provide the cheapest way of allowing 2 3KW heaters in arbitary locations

4mm radials do have thier advantages but are harder to wire especially if you want to spur from a socket (mk say thier sockets will take 3x4mm but i bet its tight in the backbox)

2.5mm raidals also have advantages but there is the risk of some idiot putting them on a 32A breaker

rings also have disadvnatages mind you mainly that if they stop being a ring due to damage or kitchen fitters it is not obvious and so doesn't get fixed

Title: Re: Flat rewire
Post by L.Spark on Dec 7^th, 2004, 7:59pm

Quote:

LS - what's your reasoning?

I don't mind either particualy, Alot of it comes down to application, I removed about 25 radial circuits and replaced the lot with 2 rings at one place.

The reason for using radials was because it was a small supermarket and rings would be highly unsuitable for running many fridges/freezers, but the wiring was a mess and after the purpose of the building was changed rings suited better.

The only thing with a radial is there are limits on floor area, regs say 50sqm for a 20A radial iirc, where as a 32A ring can serve 100sqm