Adding Electrics to a new house

[NDavison]

I've just recentlt purchased a new build house but want to have some addtional electrical work done. I've had two quotes from electricians who are part p qualified but they have both told me different things and their prices vary by quite a bit. If anyone has any advice on the issues I outline below it would be appreciated. It will be an electrician who does the work but not sure which one to go with.

Work asked to be carried out:

1) We would like some down lights fitted underneath the kitchen units. As the cooker hood is attached to a single socket the electrian has said he would connect a fuse spur switch to the single socket that powers the cooker hood and wire the downlights to the fuse spur switch. Is this acceptable? The second electrician said this is not possible and breaks the regulation as the single socket for the cooker hood is connected to appliance grid switch on the wall and then the grid switch is direct to the consumer unit. He said the single socket for the cooker hood is a spur from the grid switch as it has only one set of cables and by taking a fuse spur switch of the socket you are taking a spur of a spur and this is not allowed. I know you can't take a spur of a spur but the first electrician said its not taking a spur of a spur. The second electricians suggestion was to take it from another socket but the nearest sockets would involve taking numerous tiles of the wall etc. Any advice?

2) We want to add a socket in the hall and the consumer unit is directly above where we want to add the socket. Are you able to connect a double socket direct to the consumer unit as advised by the electrician. It would be connected to the same point as the downstairs ring but would not be joined to the ring. Is this acceptable? The second electrician has said its not and would need to be part of the downstairs ring so the ring broken into at some point. He said you shouldn't join direct to the consumer unit unless its on a breaker of its own and it wouldn't be.

3) We want to extend the upstairs ring to allow for extra sockets in the bedrooms by taking it through the loft. The second electrician said it was a no go as its taking the space of the ring over 100m square. The ring already goes through each room so this would be doubling its size.

4) We want to add some outside lights. The garage already has a socket and a fuse spare switch for the lighting (its a strip light). Can the outside lights be taken from the same fuse spare as the inside light? The second electrician says no and says that actually the way the builders have done the socket in the garage is wrong. It seems the socket in the garage is a spur of a socket in the kitchen and then the fuse pur switch has been connected to the socket. Is this wrong to? This is wht the builders did and it has all been certified.

Any advice would be appreciated.

 

[riveralt]

I've just recentlt purchased a new build house but want to have some addtional electrical work done. I've had two quotes from electricians who are part p qualified but they have both told me different things and their prices vary by quite a bit. If anyone has any advice on the issues I outline below it would be appreciated. It will be an electrician who does the work but not sure which one to go with.

Bet you wished you had sorted this out while it was being built!!!

1) We would like some down lights fitted underneath the kitchen units. As the cooker hood is attached to a single socket the electrian has said he would connect a fuse spur switch to the single socket that powers the cooker hood and wire the downlights to the fuse spur switch. Is this acceptable? The second electrician said this is not possible and breaks the regulation as the single socket for the cooker hood is connected to appliance grid switch on the wall and then the grid switch is direct to the consumer unit. He said the single socket for the cooker hood is a spur from the grid switch as it has only one set of cables and by taking a fuse spur switch of the socket you are taking a spur of a spur and this is not allowed. I know you can't take a spur of a spur but the first electrician said its not taking a spur of a spur. The second electricians suggestion was to take it from another socket but the nearest sockets would involve taking numerous tiles of the wall etc. Any advice?.

You cannot run a spur from a spur in a ring final circuit. If it is a radial then you can.

2) We want to add a socket in the hall and the consumer unit is directly above where we want to add the socket. Are you able to connect a double socket direct to the consumer unit as advised by the electrician. It would be connected to the same point as the downstairs ring but would not be joined to the ring. Is this acceptable? The second electrician has said its not and would need to be part of the downstairs ring so the ring broken into at some point. He said you shouldn't join direct to the consumer unit unless its on a breaker of its own and it wouldn't be.

There is nothing to stop you runing a spur from the consumer unit MCB - provided the same cable size is used.

3) We want to extend the upstairs ring to allow for extra sockets in the bedrooms by taking it through the loft. The second electrician said it was a no go as its taking the space of the ring over 100m square. The ring already goes through each room so this would be doubling its size.

You advised not to exceed 100m sq m - consider adding another ring if your Consumer Unit will allow.

4) We want to add some outside lights. The garage already has a socket and a fuse spare switch for the lighting (its a strip light). Can the outside lights be taken from the same fuse spare as the inside light? The second electrician says no and says that actually the way the builders have done the socket in the garage is wrong. It seems the socket in the garage is a spur of a socket in the kitchen and then the fuse pur switch has been connected to the socket. Is this wrong to? This is wht the builders did and it has all been certified.

You cannot have a spur from a spur on a ring final circuit - so if it is from a ring final circuit then the answer is no and the switched fcu is wrong as well.

 

[NDavison]

Thanks riveralt. Although it is a new build it was all sorted before we bought it.

For the kitchen downlights. Would you say the socket for the cooker hood is a radial? I know the apliance grid switch (for the cooker hood, washing machine etc) is conected direct to the consumer unit and from the appliance grid switch the cooker hood socket is connected directly and presumably the other appliances such as cooker are also connected directly to the aplliance grid switch.

Is there a limit to the number of sockets you can connect direct to the consumer unit? They wouldn't be part of the ring but connected direct to the same breaker in the consumer unit as the downstairs ring.

Is the 100m square still appropriate to the size of the coverage space for a ring? Having read some other posts it suggests the space size of 100m square is now not valid since the 17th edition. We can't add another ring as the consumer unit will not allow. We thought the option was to extend the upstairs ring. But is the space size still valid?

 

[Chri5]

Thanks riveralt. Although it is a new build it was all sorted before we bought it.?

If you need to change things then it's not really sorted, is it? Like every house in the land you have moved in and the setting of some electrics isn't right for you. Unfortunately the wiring contractor was given a set of drawings from a person who dreamed your house. I doubt he ever intended to live there.

For the kitchen downlights. Would you say the socket for the cooker hood is a radial? I know the apliance grid switch (for the cooker hood, washing machine etc) is conected direct to the consumer unit and from the appliance grid switch the cooker hood socket is connected directly and presumably the other appliances such as cooker are also connected directly to the aplliance grid switch.?

Go play with the fuses at the board. if you think a bank of switches are on a radial the easiest way to prove that is turn the fuse off and see what happens.

As to is it a ring or a radial only simple testing will tell- although ripping the board lid off and seeing if there's only one live (radial) or two lives (mostly rings)**

** A radial circuit, could at the board have 2 lives, 1 being for a direct spur- so investigation via visual at each circuit point and test is necessary!

Is there a limit to the number of sockets you can connect direct to the consumer unit? They wouldn't be part of the ring but connected direct to the same breaker in the consumer unit as the downstairs ring.?

One and no more

Is the 100m square still appropriate to the size of the coverage space for a ring? Having read some other posts it suggests the space size of 100m square is now not valid since the 17th edition. We can't add another ring as the consumer unit will not allow. We thought the option was to extend the upstairs ring. But is the space size still valid?

No it's not, bedroom levels have very low demand and most products work >210v so voltage drop isn't really an issue.

It's common sense to support high use, high demand circuits. If all else fails split the ring, and make 2 x 20 amp radials which in 95% of the house will be fine. The 5% Not = kitchen

 

[riveralt]

For the kitchen downlights. Would you say the socket for the cooker hood is a radial? I know the apliance grid switch (for the cooker hood, washing machine etc) is conected direct to the consumer unit and from the appliance grid switch the cooker hood socket is connected directly and presumably the other appliances such as cooker are also connected directly to the aplliance grid switch.

Because its a new build, you should have been given wiring diagrams of the circuits identifying amongst other things the type of circuit each one is.
The problem with giving a specific answer to your question can be summarised by - If the socket for the cooker hood has two sets of cables in it then it could be part of the ring final circuit or radial circuit. If it has one set then it could be a spur of a ring final circuit or the end of a radial circuit. So without a wiring diagram or testing it is impossible to say.

Is there a limit to the number of sockets you can connect direct to the consumer unit? They wouldn't be part of the ring but connected direct to the same breaker in the consumer unit as the downstairs ring.

If the MCB in a consumer is part of the ring final circuit - only one spur can be taken from it.

Is the 100m square still appropriate to the size of the coverage space for a ring? Having read some other posts it suggests the space size of 100m square is now not valid since the 17th edition. We can't add another ring as the consumer unit will not allow. We thought the option was to extend the upstairs ring. But is the space size still valid?

The exact wording in the 17th edition (updated) are "taking account of the total floor area being served, historically a limit of 100m2 has been adopted."

So there is nothing to say that limit must be applied, but you do have to take into account voltage drop when adding to circuits and doubling the size of the ring final circuit you are talking about will probably bring that factor into play.

 

[NDavison]

The cooker hood socket is resting on top of the units and you can definately see that there is only one set of cables going into it. We didn't receive any wiring diagrams, just a certificate! If the cooker hood socket is one set of cables direct to the grid switch and the grid switch is direct to the consumer unit would this suggest a radial? Or does the fact that the grid switch has probably three other cables coming of it direct to appliance sockets (washing machine etc) change this?

 

[Chri5]

It could be a mix on the grid.

You can have separate circuits on a set of grids- there's an 8 plate module and you could have lights, cooker, boiler etc all one one switch bank- but separate circuits.

I mentioned in my last post that turning off fuses / circuits at the board will give you a clearer indication to resolving assumptions currently being suggested.

(get off your pc and go and check )

 

[NDavison]

I've also had a further look at the power to the garage as I'm now thinking that what the builders have done is wrong. The socket in the garage has only got two sets of cables to it and there is a fuse spare next to it with two sets of cable to it also. From the fuse spur one set of the cables goes to the strip light and I'm presuming the second set of cables is connecting it to the socket thus making it a spur. Therefore, that means in the socket one set of cables goes to the fuse spur and the second set must come of a socket or something but still making the socket a spur also seeing as it only has two sets of cables and the fuse spur must be joined to one of these. When you turn the downstairs sockets of at the consumer unit both the socket and the lighting in the garage don't work so the socket must be spured from a socket in the kitchen. Does it seem likely that the socket in the garage is a spur? And if it is, it is wrong to take the fuse spur for the lights from this socket isn't it? Or because the fuse spur is for lighting is this different ?

 

[mfarrow]

Going through your requests:

1) You say the second electrician has told you the grid switch takes power directly from the conumer unit (radial) and then you say it'd be a spur off a spur?? A spur is only associated with ring circuits; what is the rating of the breaker for this circuit?

2) The second electrician is wrong - no problem you connecting a spur to the ring main at the origin of the ring main.

3) You are creating more sockets in the bedrooms, from the existing upstairs ring (?), and the second electrician says this will take the overall area above 100m²??? Unless these rooms aren't already served by the upstairs ring (unlikely) then this particular recommendation from the regulations will not be a problem.

4) That does sound wrong if you've got a spur off a spur. If you're sure the downstairs circuit is a ring then this needs looking at and correcting.

 

[NDavison]

I'm pretty sure the downstairs is a ring as it has two cables at the consumer board. From earlier posts i'm presuming the two cables means a ring and if there is one it means radial. There are no spares from the consumer unit direct yet. Wouldn't rings be used in new builds?

If you turn the downstairs ring of at the unit then the garage light and socket don't work. And I've had a look behind one of the kitchen sockets which shares a wall with garage and this has three sets of cables coming from it so it looks like this is probably the spur to the garage. I take it that the fact that the fcu is being used for lighting doesn't make any difference? Its still classed as a spur of a spur. If the socket was part of a ring it would need three sets of cables wouldn't it seeing as the fuse spur is a spur.