Cannot have a Spur off a spur but can use an extension lead?

[Brian Matthews]

Probably a stupid question but why is it that you cannot (I think) run a spur off a spur but can connect an extension lead with loads of sockets on it? My son needs about six sockets in a new kitchen where there is only one double socket at present. How can it be done? As a matter of interest, we are trying to get an electrician in the Whitehaven, Cumbria area with no success. Are they all too busy?

Thanks

Brian

 

[telectrix]

the reason you can do it is that the extension lead is fused at 13A and so even if you overload the exrension, the 13A fuse will blow and the fixed wiring will not be subjected to overload.

 

[Brian Matthews]

the reason you can do it is that the extension lead is fused at 13A and so even if you overload the exrension, the 13A fuse will blow and the fixed wiring will not be subjected to overload.

Thanks for that, so if a fused double socket could be found (if such a thing exists), would that be OK?

 

[Baddegg]

Thanks for that, so if a fused double socket could be found (if such a thing exists), would that be OK?

Or if I’m understanding correctly you could spur of off the double into a 13a fused spur and put what you like after that point, although probably not a great design in a kitchen if I’m honest….thinking tumble dryer iron kettle toaster…..you’ll soon get bored of that fuse popping….plenty of good sparks on here from your way I’m sure one of em will be happy to have a look ?

 

[Brian Matthews]

the reason you can do it is that the extension lead is fused at 13A and so even if you overload the exrension, the 13A fuse will blow and the fixed wiring will not be subjected to overload.

Just found these:

MK 13 Amp Double Pole Fused Triple Switched Socket​

Isn't this just like have a 'built in' extension lead?

 

[timhoward]

It depends if you want the hassle of calculating loads…for example a kettle, toaster and microwave exceed 13 amps if all run together.

 

[Brian Matthews]

It depends if you want the hassle of calculating loads…for example a kettle, toaster and microwave exceed 13 amps if all run together.

Well it's not hard to calculate loads, just convert all the powers to current and add them up. So, theoretically I could use one as long as all loads come to less (ideally) than 13A.

 

[pc1966]

Is the double socket currently in the kitchen already a spur? If it is part of a ring final circuit (RFC) then that ring could be looped around another couple of sockets.

Kitchens normally need proper provision of power (professionally, not necessarily by Peter Piper...) as they are often the highest concentration of high power appliances, such as cookers, dishwashers, kettles, washing machines, etc. All heat stuff and that is power-hungry. So really it is something you should consider having done by a spark.

As already mentioned, if you have an over current protective device such as a 13A fuse then whatever you add beyond that can't overload the supply cable, as if it is already a spur it is probably on 2.5mm cable and that is often only able to carry 20A (or occasionally less, if in a hot region or thermally well-insulated) so by extending it carelessly you risk it overheating as (probably) the RFC feeding it is on a 32A breaker due to the provision of two cables to each point.

 

[pc1966]

Just found these:

MK 13 Amp Double Pole Fused Triple Switched Socket​

Isn't this just like have a 'built in' extension lead?

Essentially, yes. They include the 13A fuse as there is a high probability of it being used as a spur.

What is "legitimate" is to have a 13A FCU feeding a set of sockets, essentially a hard-wired extension lead, but as already said, it is bad practice in most cases as the end users typically will NOT calculate the usage and so will blow the fuse regularly and be tempted to do something stupid like stick a bolt in its place. Really if it is more than the odd "I need a 3rd socket" for a bedroom or similar then it should be done properly, so extending the ring, wiring in a new circuit, or in some cases when the house wiring is already screwed up by past DIY/builders monkeying with things by dropping the supply OCPD to 20A so all 2.5m wire is fairly safe.

 

[Brian Matthews]

Is the double socket currently in the kitchen already a spur? If it is part of a ring final circuit (RFC) then that ring could be looped around another couple of sockets.

Kitchens normally need proper provision of power (professionally, not necessarily by Peter Piper...) as they are often the highest concentration of high power appliances, such as cookers, dishwashers, kettles, washing machines, etc. All heat stuff and that is power-hungry. So really it is something you should consider having done by a spark.

As already mentioned, if you have an over current protective device such as a 13A fuse then whatever you add beyond that can't overload the supply cable, as if it is already a spur it is probably on 2.5mm cable and that is often only able to carry 20A (or occasionally less, if in a hot region or thermally well-insulated) so by extending it carelessly you risk it overheating as (probably) the RFC feeding it is on a 32A breaker due to the provision of two cables to each point.

Thanks for the informative reply. I would love to employ a sparky, if I can find one. Two came, looked at it and suggested a new consumer unit (which we do need) and various other suggestions. Not heard from them since. I don't smell so do not understand why we cannot get one. Need someone to fit a new, larger consumer unit and extra sockets in various places. I can do some thing myself but consumer units are a no no. I would prefer the other wiring to be done as we would then get a certificate (I hope).

 

[pc1966]

Thanks for the informative reply. I would love to employ a sparky, if I can find one. Two came, looked at it and suggested a new consumer unit (which we do need) and various other suggestions. Not heard from them since. I don't smell so do not understand why we cannot get one. Need someone to fit a new, larger consumer unit and extra sockets in various places. I can do some thing myself but consumer units are a no no. I would prefer the other wiring to be done as we would then get a certificate (I hope).

Can you post a photo of the CU?

If there is no RCD provision for the sockets then any legitimate sparky won't fit more - it is against the regulations as they now stand (replacing a broken socket is OK though). If you can post an approximate location (e.g. town) there might be someone on here that covers your area.

In England and Wales replacing a CU is notifiable work under Part P of the building regulations. That was brought it largely due to the number of fires and other safety incidents. While Scotland and (I think) NI don't have that specific rule yet, the CU should be considers as a job only for professionals: folk with the knowledge, practical skills, and test equipment to do it safely.

 

[Brian Matthews]

Can you post a photo of the CU?

If there is no RCD provision for the sockets then any legitimate sparky won't fit more - it is against the regulations as they now stand (replacing a broken socket is OK though). If you can post an approximate location (e.g. town) there might be someone on here that covers your area.

In England and Wales replacing a CU is notifiable work under Part P of the building regulations. That was brought it largely due to the number of fires and other safety incidents. While Scotland and (I think) NI don't have that specific rule yet, the CU should be considers as a job only for professionals: folk with the knowledge, practical skills, and test equipment to do it safely.

Please find attached pic. If you wanted the inside pic let me know. I live in Whitehaven, Cumbria.

 

[timhoward]

That's an interesting one. It's certainly a very good brand - I rejoice if I find a Hager in a domestic property!
I think there's at least two spare ways on it and there looks to be enough height to get RCBO's in, so a new up-to-regs circuit for the kitchen might be possible without a new board.
Changing all circuits to RCBO would cost almost as much as a new loaded board though - so this is one to weigh up in terms of desired outcomes.

 

[pc1966]

Shame no labels! I'm guessing up/down lights, up/down RFC (sockets), immersion heater, cooker?

As @timhoward says Hager are a top brand but, while i have used them commercially, I don't know how long they have retained compatibility. One for @westward10 ?

If budget is tight, etc, then I would consider changing the MCBs for the socket circuits to RCBOs and, provided the kitchen socket is on one of the RFC, extend that to a few more. These days most circuits should have RCD protection as there have been deaths attributed to penetrating cables buried in walls, but pragmatically it is the sockets on ground floor (where extension leads are likely used outside) and on any floor if bathroom heated towel, etc, that are by far the biggest risk for shock.

 

[Brian Matthews]

Shame no labels! I'm guessing up/down lights, up/down RFC (sockets), immersion heater, cooker?

As @timhoward says Hager are a top brand but, while i have used them commercially, I don't know how long they have retained compatibility. One for @westward10 ?

If budget is tight, etc, then I would consider changing the MCBs for the socket circuits to RCBOs and, provided the kitchen socket is on one of the RFC, extend that to a few more. These days most circuits should have RCD protection as there have been deaths attributed to penetrating cables buried in walls, but pragmatically it is the sockets on ground floor (where extension leads are likely used outside) and on any floor if bathroom heated towel, etc, that are by far the biggest risk for shock.

From left to right the CB's control: 1. Kitchen oven and left hand skts, 2. kitchen RH skts, 3. Gas boiler and upstairs skts (three floors), 4. Living room and lounge skts, 5. some downstairs skts, 6. all lights

Shame no labels! I'm guessing up/down lights, up/down RFC (sockets), immersion heater, cooker?

As @timhoward says Hager are a top brand but, while i have used them commercially, I don't know how long they have retained compatibility. One for @westward10 ?

If budget is tight, etc, then I would consider changing the MCBs for the socket circuits to RCBOs and, provided the kitchen socket is on one of the RFC, extend that to a few more. These days most circuits should have RCD protection as there have been deaths attributed to penetrating cables buried in walls, but pragmatically it is the sockets on ground floor (where extension leads are likely used outside) and on any floor if bathroom heated towel, etc, that are by far the biggest risk for shock.

 

[pc1966]

From left to right the CB's control:

I was going right to left from main switch.

1. Kitchen oven and left hand skts, 2. kitchen RH skts, 3. Gas boiler and upstairs skts (three floors), 4. Living room and lounge skts, 5. some downstairs skts, 6. all lights

#5 seems unlikely it is a 6A MCB so sockets won't hold up much!!!

#2 is odd, could be like my kitchen when an old immersion heater circuit was repurposed as a socket. Are those the sockets you want to extend? If so, and it is wired in 2.5mm (have to double-check that as potentially 1.5mm could be used on a 16A circuit) then replacing with a 20A RCBO and extending as a radial would be reasonable, so long as total load at any time is less then 4.6kW

 

[Brian Matthews]

From left to right the CB's control: 1. Kitchen oven and left hand skts, 2. kitchen RH skts, 3. Gas boiler and upstairs skts (three floors), 4. Living room and lounge skts, 5. some downstairs skts, 6. all lights

 

[Brian Matthews]

Would one of these be suitable 'BRITISH GENERAL FORTRESS 32A 30MA SP TYPE B MINI-RCBO' on a DIN rail mounted fitting. I don't know what this rail fitting means.​

 

[Brian Matthews]

I was going right to left from main switch.

#5 seems unlikely it is a 6A MCB so sockets won't hold up much!!!

#2 is odd, could be like my kitchen when an old immersion heater circuit was repurposed as a socket. Are those the sockets you want to extend? If so, and it is wired in 2.5mm (have to double-check that as potentially 1.5mm could be used on a 16A circuit) then replacing with a 20A RCBO and extending as a radial would be reasonable, so long as total load at any time is less then 4.6kW

I agree that 5 is odd but it is a 6A and IS controlling some downstairs skts. Will have another check tomorrow as to exactly what skts it is controlling. I do need to add another two cct breakers and will use RCBO's. Don't know what type/size to get though. I posted earlier the type that might be suitable. (Do they all tend to be mini ones?)

 

[westward10]

Would one of these be suitable 'BRITISH GENERAL FORTRESS 32A 30MA SP TYPE B MINI-RCBO' on a DIN rail mounted fitting. I don't know what this rail fitting means.​

No it must be a Hager device.

Hager Reduced Height 30mA 6kA Type B 32A RCBO - ADA332G

Get the Hager ADN132 30mA 6kA Type B 32A RCBO at the best trade price with fast, free delivery available from Electrical2Go.

www.electrical2go.co.uk

 

[pc1966]

I agree that 5 is odd but it is a 6A and IS controlling some downstairs skts. Will have another check tomorrow as to exactly what skts it is controlling.

In some cases you would see the old 5A round-pin sockets being used for lights, such as stand lamps in hotels, etc. Using a 6A circuit for 13A sockets is wrong in a number of ways!

I do need to add another two cct breakers and will use RCBO's. Don't know what type/size to get though. I posted earlier the type that might be suitable. (Do they all tend to be mini ones?)

As @westward10 posted it must be the Hager ones. Contrary to common sense and other industry norms, CU do not have standard busbars and so only the manufacturer's compatible ones should be used. This is an issue not just between manufacturers, but also in some cases between generations with the same manufacturer. Looking at you, Wylex!

If you are contemplating changing the 16A MCB for a 20A RCBO you really must verify the cable is suitable, as whoever designed it originally used a 16A MCB for some reason. Quite what it was is not obvious, might have been a previous fixed load like an immersion heater, might have been due to them only having an old roll of 1.5mm in the van. Whatever the reason was is probably ost in the mists of time, so it becomes a job now to determin if the cable is safe for 20A in such a case.

 

[brianmoooore]

Or if I’m understanding correctly you could spur of off the double into a 13a fused spur and put what you like after that point, although probably not a great design in a kitchen if I’m honest….thinking tumble dryer iron kettle toaster…..you’ll soon get bored of that fuse popping….plenty of good sparks on here from your way I’m sure one of em will be happy to have a look ?

If the socket is already a spur, you can't feed from there to a fused spur and then on to other sockets. The fused spur will have to go before the existing socket, then feed that socket and as many additional sockets as you like (disregarding expected loads).

 

[Brian Matthews]

Thanks for all of your interest. I think the best way forward (if I can get a sparky to do the job) is to get a new CU installed. That would save a few problems.

Thanks again, I have learned a lot

Brian

 

[UNG]

One socket in a kitchen when you need six would suggest the wiring may be quite old, the question would then be how many sockets short is the rest of the property and it may be better to consider a full rewire than doing ad hoc minor / major upgrades to an old circuit which may not meet the regs and pass the necessary testing

 

[Brian Matthews]

When I get a new CU, would it be good enough to get one populated with RCD's instead of RCBO's? That would cut the cost a lot. Thinking about Schneider or Wylex ones. Any advice would be greatly appreciated instead of me diving in and buying a totally inadequate one.

Thanks

Brian

P.S. Still looking for a sparky

 

[SJD]

Far better to have a unit with all RCBOs. Then a circuit fault only trips the one circuit, not half the house!

 

[brianmoooore]

One socket in a kitchen when you need six would suggest the wiring may be quite old,

The recommendation for a least six sockets in a kitchen goes right back to 1961, with the release of the Parker Morris report

 

[brianmoooore]

Far better to have a unit with all RCBOs. Then a circuit fault only trips the one circuit, not half the house!

This is true, but insinuates that this is likely to be a regular event. Going by my own experience, with the split load CUs in my own house, a RCD trip only happens every few years or so.
It's DP MCBs that are missing in the UK, which would isolate earth neutral faults on split boards, enabling the RCD to be reset and keep the majority of circuits working

 

[Brian Matthews]

The recommendation for a least six sockets in a kitchen goes right back to 1961, with the release of the Parker Morris report

I should have made myself clear with regards to the kitchen. We have a three story Victorian house. The present kitchen is on the ground floor. My son will be living on the top two floors and the kitchen I was referring to (not very clearly) is to have another kitchen in a first floor room, this is the one with only one skt. Checked the skt last night and it has only two cables in it. So presumably it is not a spur?

 

[timhoward]

I should have made myself clear with regards to the kitchen. We have a three story Victorian house. The present kitchen is on the ground floor. My son will be living on the top two floors and the kitchen I was referring to (not very clearly) is to have another kitchen in a first floor room, this is the one with only one skt. Checked the skt last night and it has only two cables in it. So presumably it is not a spur?

You are right that it is most likely not to be a spur. We can't ever presume!
I'm not trying to be pedantic but it could be:
1 - an incorrectly installed spur leading to another spur
2 - a radial circuit fed from (generally) a 16A breaker or less
3 - part of a ring final circuit that is no longer a ring due to a fault elsewhere.

That said if it was installed to regs at the time, and turning off a 32A breaker stops the socket working then you have an above average chance that it's not a spur and all is ok. But these are some of the reasons we do dead-testing before modifying a circuit, to make sure all is as it seems to be and is still functioning as the original circuit designer intended.

 

[pc1966]

When I get a new CU, would it be good enough to get one populated with RCD's instead of RCBO's? That would cut the cost a lot. Thinking about Schneider or Wylex ones. Any advice would be greatly appreciated instead of me diving in and buying a totally inadequate one.

Better to go with RCBOs, especially as you only have 6 circuits and might only need another one or two later, so cost difference to a dual-RCD board is small.

Schneider and Hager are the top ones, but rare in domestic settings and far more common in industrial sites.

Wylex and Crabtree are "traditional" brands and fine, they have double-pole switching RCBOs that make circuit testing simpler (used Wylex for my own flat).

Current favourite around these parts for the budget end is Fusebox, similar compact RCBOs to Wylex/Crabtree and very reasonable prices. Realistically a CU change cost is dominated by the labour (of course depending on any faults found that need fixing to make the system compliant and RCD-tolerant, such as "borrowed neutrals") so spending an extra £100 or so for less trouble down the road is a very good idea.

RCD/RCBO by their nature are prone to the occasional trip and with RCBO you only lose one circuit, not a bunch off the same RCD. Should there be a fault later then it is also contained to the one circuit that is impacted by it, making finding it quicker and cheaper.

 

[pc1966]

Checked the skt last night and it has only two cables in it. So presumably it is not a spur?

You mean two twin&earth cables, not two conductors (red & black, or brown & blue)?

As mentioned above, before modifying something you really have to find out what it is and how it is connected to the rest! Get a half-decent socket tested such as this:

TIS Socket Tester With Loop & RCD Check

A pocket sized checker for indicating loop impedance, socket polarity and RCD 30mA are all ok. Indication is by LED's and buzzer. An ideal unit for initial "checking out" of a 13A socket and will advise if the circuit is ok, needs attention, or needs urgent attention. An ideal product for...

www.toolstation.com

And you can see what goes on/off with difference MCBs. It might not be what you thought!

NOTE: Don't press the RCD test button for any length of time on that as you have no RCD and will just cook the resistor that causes the test current to be diverted (normally the RCD would trip off in tens of milliseocnds so resistor safe).

 

[timhoward]

I second the Fusebox suggestion - very good quality for the price.
I think the dual RCD vs RCBO question has been well answered - when everything is properly working as intended a dual RCD board is adequate.
When everything isn't working things rapidly become quite tricky especially with Neutral to Earth faults.
( Thomas Nagy recently made a video discussing this.

)

 

[brianmoooore]

It's DP MCBs that are missing in the UK, which would isolate earth neutral faults on split boards, enabling the RCD to be reset and keep the majority of circuits working

 

[timhoward]

Apologies @brianmoooore , I didn't check the previous page....