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

[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....