Kitchen nightmare

[New Venture!]

Hi all. Could I ask for clarity on something I'm puzzling over? (Currently at home suffering badly from hay fever so not thinking fully clearly!) I was asked to raise some sockets in a kitchen for a customer who wants granite splashbacks fitted. Long story cut short the electrics were installed by kitchen fitters a few years ago and are a disaster. Sockets that supplied most of the appliances were fed by radial run in 1.5mm T&E which is spurred off a 32amp ring. Customer after some discussion (and because the consumer unit is on the wall behind the kitchen) has agreed to me running a new 32amp ring to replace this and as all appliances are on one wall all good. Now the issue. On another wall there is a fused flex outlet (1 amp fuse feeding LED lighting) and a USB double socket. These are fed by 2.5mm T&E spurred from a socket in the lounge and makes a "spur from a spur" which is a no-no. Customer does not want any mess on either this wall or the lounge, nor do they want to loose either the LED lights or the socket. My idea? Derate the ring circuit from which this spur is taken to 20 amp. Customer does not have anything of any great current draw (no heaters etc) so I don't anticipate an increase in nuisance tripping. Is this an acceptable solution that means no mess or am I being stupid? 

 

[Rob_the_rich]

Best solution is to leave it as it is. Even though it is a spur from a spur, it is unlikely to draw more than 27 amps, 2x13A sockets and 1A lights at maximum, which is the same as the current carrying capacity of the 2.5mm iirc.

 

[Essex1]

Agreed. Maybe put a label on saying "max fuse 3A only to be fitted" as an extra precaution. 

 

[roys]

How about fitting a fused spur at the origin or the spur using a twin back box and so changing the double socket (I presume) to a single socket and a fused spur. 

 

[Doc Hudson]

Are you saying that the kitchen and the lounge are now two separate circuits rated at 32A each each. If so I would agree with your suggestion of make the lounge a 20A circuit. Assuming its a relatively common CU I would guess a 20A MCB would be between £5 to £10 tops. So hardly going to break the bank and you will have a more fail safe solution that covers your back. Very unlikely to trip the 20A if the bulk of the kitchen is off a separate 32A. The cheap and no mess solution would be my choice.

Doc H.

 

[Rob_the_rich]

Might sound cheaper just to replace the ocpd for the lounge circuit, but it would require full tests and a full EIC, as it would be a new circuit.

As it is, the works to the kitchen ring are only minor works, as only altering an existing circuit.

Best to just leave it I think. Agree with Essex about labelling the FCU, and also labelling the kitchen ring "all kitchen sockets except usb double socket and LED FCU"

 

[Doc Hudson]

Might sound cheaper just to replace the ocpd for the lounge circuit, but it would require full tests and a full EIC, as it would be a new circuit.

As it is, the works to the kitchen ring are only minor works, as only altering an existing circuit.

Best to just leave it I think. Agree with Essex about labelling the FCU, and also labelling the kitchen ring "all kitchen sockets except usb double socket and LED FCU"

I think you will find there is already the need for an EIC as a new 32ring has been added "customer has agreed to me running a new 32amp ring to replace this". Plus I assume he has already worked on the second circuit as part of the "asked to raise some sockets in a kitchen for a customer who wants granite splashbacks fitted" work. If you are suggesting all of this can be fitted on to one MWC the I would have to disagree with you. Testing the one circuit to make it a 20A and filling in the paper work certainly would not be a major issue of cost or time in addition to what has got to be done anyway. Plus its already notifiable work if a new ring has been added.

Doc H. 

 

[Sharpend]

Agree with the doc on this, I think rtr has misread? 

 

[Rob_the_rich]

I didn't read that as a new circuit, there is an existing 32A ring from which 1.5mm radials were run to appliances.The replacement is to replace the radials with a ring. Socket positions moved up a bit. I might be wrong though, been wrong before, will be again.

Edit; I mean to extend the ring to include the appliances currently served by unfused spurs wired in 1.5mm.

I read that the usb DS and the LED fcu off the lounge circuit have not been worked on (customer instructions), only inspected to ascertain what circuit they are on and the wiring arrangements. So no need to include that circuit in any certification.

 

[Rob_the_rich]

This spur from a spur thing is a bit confusing. I can only find one mention of it in bs7671 on page 453 Appendix 15 (informative). In fig 15A "unfused spur- an unfused spur should feed one single or one twin socket outlet only. ..." This is to comply with 433.1.204, which basically says 433.1 is satisfied if the current carrying capacity (Iz) must be > or = to 20A and that "..the load current...is unlikely to exceed for long periods the current carrying capacity of the cable". In the example of the DS and fcu, the Iz will not be exceeded by the characteristics of the load (2x13A +1A) as long as the installation method is method C. So there is no regulation I can find which this example of a "spur from a spur" does not comply with. It only doesn't comply with a note in an informative appendix which is there to give examples of how compliance with 433.1.204 can be achieved.

Any thoughts on this?

 

[Sharpend]

Think a little harder about that which you have copied from regs. 

A piece of 2.5 will carry approx 27A, if you have a double socket then it will comply, extend the circuit with another length of 2.5 and add an additional socket- how many amps is the first piece of 2.5 going to have to carry? 

 

[New Venture!]

Thanks for your replies guys, much appreciated.

Doc, yes, the kitchen (apart from the USB port socket and flex outlet mentioned) is now on a completely new 32 amp ring (rest of the downstairs on separate original ring) so I'm going to notify. They also want all the switches and sockets in the house changed for stainless ones so I'm going to do an EICR. 

Roys, I like your idea. I'll run it past the customer.  (CU is a Crabtree Starbreaker) 

 

[Rob_the_rich]

Think a little harder about that which you have copied from regs. 

A piece of 2.5 will carry approx 27A, if you have a double socket then it will comply, extend the circuit with another length of 2.5 and add an additional socket- how many amps is the first piece of 2.5 going to have to carry? 

Who mentioned an additional socket? I think you have mis-read my post.

 

[Sharpend]

Who mentioned an additional socket? I think you have mis-read my post.

A spur from a spur? Or rewritten as A load from a load? 

 

[Rob_the_rich]

A spur from a spur? Or rewritten as A load from a load? 

433.1.204 starts with "Accessories to BS 1363.." this standard includes socket outlets and FCUs.

I don't get your point.

 

[Sharpend]

Ok Rob, your intial post said that you find this spur from a spur thing confusing, referencing the appendix and reg 433, perhaps I've gotten hold of the wrong end of the stick? What is it that you find confusing? 

 

[Rob_the_rich]

Ok Rob, your intial post said that you find this spur from a spur thing confusing, referencing the appendix and reg 433, perhaps I've gotten hold of the wrong end of the stick? What is it that you find confusing? 

I said it was confusing, I didn't say that I was confused. The OP said that this particular "spur from a spur" was a "no no", I have tried to show that it complies with the regs, but does not comply with an informative appendix. Blanket statements such as this "no no" should be examined I think.

 

[Sidewinder]

rob,

You may have fallen foul of terminology.

If you look carefully at the definitions, an FCU, is NOT a spur in the regs, the spur is the piece of cable running from the ring to the socket, FCU etc. etc.

Now if this is say "2.5 FTE" then if may be rated @ for example, 24A, so, a single piece of cable from, the ring to a socket as a spur is fine, as a 13A twin socket is only rated @ 20A.

Now if you take this to another socket then you can draw 40A between the two sockets, 20A at the first & 20A at the next.

OK, yes the RFC OCPD is only 32A, however, this is more than the "first" bit of "2.5 FTE" can carry given a 24A rating.

The Weasel words used in BS7671 really must be read more carefully and referenced to their origin, which, these days is NOT the Oxford English Dictionary.

 

[Rob_the_rich]

I never mentioned a socket fed via a double socket fed from an unfused spur.

I only used the phrase "spur from a spur" because that is what the OP said. I think others are confused by what this means, which is what I posted.

I deliberately try to say FCU and not "fused spur", because they are different.

The case in point here is a double socket fed from an unfused spur, from which another unfused spur feeds an FCU. The OP said that any spur from a spur is a no-no, I disagreed.

As it turns out, I was wrong about the extent of the works on the kitchen circuit, it sounded to me like an extension but was in fact a new circuit.

 

[Sharpend]

Sorry rob, it might be because it's late but what's an unfused spur if it's not fed from a fused spur? Surely it's a piece of cable from a socket or the like? 

And for clarity: I only used a socket from a socket as an example.