Advice - Adding sockets to a cheap system

[compact]

Hi
I have moved into an old terrace, where the electrics were upgraded a while back, but to the cheapest system possible.

I have had a couple of electricians/builders looking at adding more sockets and some of them have said a new system needs to be installed.


If I find the box type and number of sockets on it at the moment, will you guys on here be able to tell me if this is true?

2nd) Bodge it and Scarper have said they will add some more sockets for £20, which is much cheaper than other quotes. How can I check he is doing a good job? What are the obvious cheap bodges and poor work, I should look out for, when the lay cables and wires i.e under floor or plastering.

 

[Chri5]

Without giving you an extended learning curve on all areas of domestic planning, rules and installation it is near impossible to answer you query easily.

A standard domestic ring circuit should have no more than 16 x double sockets.
However diversity should be considered, diversity is a formula for load on a circuit and can be quite complex. The simple theory is that the sum of all loads should not exceed the rating of the circuit fuse and cable capacity.

So in bedrooms, halls and reception rooms diversity is high since most loads will not run simultaneously or continuously.

In a kitchen, where kettles, dish / clothes washing machines and tumble driers exist diversity will be low, since there may be fewer devices than say a general ring- but the loads are more constant and are higher.

If you could do a simple audit and offer details of how many final circuits you have, ring, radials and light radials and what you have on the circuits we can offer more detail / better response.

As for £20 per socket, that's very cheap and I would imagine that that does not include sunk back boxes, making good and testing of the service with a MW cert.

Round here, cost is about £50 a socket- minimum £100 of work to warrant visit, testing and doing the job.

 

[Taylortwocities]

And when you say 'cheapest system possible' and 'box type' what are you referring to? Is it the fuseboard or the total installation?

 

[compact]

I think the house was dragged in to the 21st century on a cheap budget.
It looks like it was re-wired in the 80's/90's with a modern fuse box, but judging by the remarks of people who have seen it, it was done on a shoe string.

 

[Steve]

PHOTOGRAPHS! We need photographs to ascertain the condition of the wiring.

 

[compact]

No worries
will provide a photo in a couple of days when I return home.

I was wondering if certain fuse boxes are only design for a certain number of sockets/load and maybe they had installed a cheap one.

 

[JohnD]

A standard domestic ring circuit should have no more than 16 x double sockets.

sorry, m8, that's not right.

Domestic rings are done by floor area, not number of sockets. the idea of the design was that you would always have plenty of sockets around without needing to move appliances or use extension leads. having lots of sockets doesn't cause peope to buy multiple tumble driers or fan heaters.

the majority of things plugged into sockets have trivial and intermittent load (table lamps, clock radios, fans, HiF, computers, fridges etc)

 

[Chri5]

A standard domestic ring circuit should have no more than 16 x double sockets.

sorry, m8, that's not right.

Domestic rings are done by floor area, not number of sockets.

I thought it was an old rule of thumb , I'm aware of the sq m / area restriction, the imposed cable length restrictions, but as a general rule of thumb I was told many moons ago (14th ed sparks) never to go over the 16 socket rule on a 32a ring.

Am I the only one who was told this?

Issue being that sockets by virtue of what they are can have veriable loads- diversity can't account for a bitter winter with 'x' number of electric heaters, electric blankets and general high load items being used.
Items such as clocks, radio's, panel TV's, lamps, PC's all have an extremely low (sub 1a) load.

So where do you draw the line regarding socket volume for unknown loads? reason I ask is that within the 50m sq and 75m sq rules you could have a socket every 1m- which wouldn't be wise even with some guess regarding diversity.

 

[tim west]

Same as JohnD says 100msq rule

 

[JohnD]

for an ordinary domestic house, I'd go with one socket ring final per floor for convenience (not load) reasons, with another for the kitchen and utility room, or wherever you keep the washing machine and tumble drier.

With central heating hardly anyone uses several fan heaters these days.

Large fixed loads (cooker, immersion, air con) on radials.

The ring will will get very little load

 

[plugwash]

generally in a domestic environment more sockets don't really mean more load, people will connect the stuff they want to connect regardless of how many sockets there are, more sockets just reduce the number of extention leads they need to use.