How to correct a non-compliant spur?

[ManicInfinity]

Hello

I've just been doing some investigating of my existing wiring as I want to spur some power into a lean-to (which is the subject of a separate topic titled "Electrics To Lean-To 'Outhouse'".

Turns out the existing wiring it is non-compliant! I have a ring-main (on a 32A MCB) that feeds sockets in the kitchen, (as well as an electric oven (the hob is gas)) and also a double socket in a separate 'utility' room. All good so far.

There is a spur from this double socket, to another double socket (in which the washing machine and dryer are plugged into). Again, all good.

However I have noticed that they have taken another spur off this double socket to power the gas boiler (which is located in an external cupboard that is situated under the stairs to the maisonette above).

So this is a unfused spur of a spur. Bad! I was hoping the spur to the boiler had come directly off the ring main, as my plan was to replace this with a FCU so I can spur to the boiler and then onto my new lean-to outhouse.

How do I remedy the current wiring? I assume I have to in order to get the new electrics in (and to) the lean-to certified. Ideally I'd like to fit an FCU between the first unfused spur (the double sockets) and the boiler. That would be ring -> unfused spur -> fcu -> spur [boiler] -> future spurs. Is that allowed as the first spur in the chain is not fused?

Fitting an FCU before the first spur (so that all the spurs in the chain are fused) isn't practical without channelling out a new back box into the wall (as I am guessing a 2G double socket FCU doesn't exist).

Any help much appreciated.

Thank you.

 

[diyer56]

To fix the multiple spur problem you would need to replace the first spur with a FCU fitted with a 13 amp fuse. Everything after this is then protected by the fuse.

The connection would then be:

ring - FCU (13A) - double socket (utility) - FCU (boiler)

In your situation however, this would not be advisable. The washing machine and drier are high powered devices. That's without the boiler and setup in your 'lean to'. I would be looking, at the very least, to extend the ring as follows:

ring - double socket (utility) - FCU (boiler) - FCU (lean to) - ring

 

[ManicInfinity]

To fix the multiple spur problem you would need to replace the first spur with a FCU fitted with a 13 amp fuse. Everything after this is then protected by the fuse.

Okay, I understand this. Why does the boiler have an FCU as well (or are you saying it is protected by the 13A FCU upstream of the double socket)?

In your situation however, this would not be advisable. The washing machine and drier are high powered devices. That's without the boiler and setup in your 'lean to'. I would be looking, at the very least, to extend the ring as follows:

ring - double socket (utility) - FCU (boiler) - FCU (lean to) - ring

I am slightly confused. Are you suggesting that I
a) include the washing machine and drier in the ring here, but then have a fused spur to boiler and lean-to
b) extend the ring all the way to the lean-to, or
c) include the washing machine and drier in the ring, then FCU spur to boiler and lean to, and then have a ring within the lean-to?

If it is the latter my original idea (in the other post) was to have a CU unit to run a 6A lighting radial and a 16A power radial... but I was advised against this.

Thanks in advance

 

[PrenticeBoyofDerry]

To correct your set up you have a couple of options you either, install a 13A FCU at the original intersection for the first spurred socket of the true ring final circuit. This then only allow a demand of 13A from that point, or you extend the ring final circuit, so all sockets are on the true ring.
The boiler FCU is in place as your boiler requires to be down fused, normally to 3Amps.

 

[PrenticeBoyofDerry]

Okay, I understand this. Why does the boiler have an FCU as well (or are you saying it is protected by the 13A FCU upstream of the double socket)?

No it will likely be protected by a 3A fuse as that is what the manufacturer will recommend as the device required.

I am slightly confused. Are you suggesting that I
a) include the washing machine and drier in the ring here, but then have a fused spur to boiler and lean-to

That would be advisable

b) extend the ring all the way to the lean-to, or

If you wish but the boiler will still require a 3A FCU

c) include the washing machine and drier in the ring, then FCU spur to boiler and lean to, and then have a ring within the lean-to?

I think that is the same as above.

If it is the latter my original idea (in the other post) was to have a CU unit to run a 6A lighting radial and a 16A power radial... but I was advised against this.

That is different issue! I will have to update myself on the status of that topic, but I recall a 2.5mm2 T&E cable being routed externally under decking, which is not best done!

 

[ManicInfinity]

Thank you

Got a much clearer understanding of what to do to solve this now. I hope I can extend the ring main... as I'd assumed those high powered machines were plugged into it until today anyway.

For the time being the boiler is plugged into a socket and protected by a 3A fuse. At least it better be 3A - I'll check in the morning. But I might get rid of the socket and hardwire it into a 3A FCU as advised. Seems weird that the boiler even has a plug!

Thank you both for your help

 

[Taylortwocities]

Seems weird that the boiler even has a plug!

A plug is an acceptable means of isolation. Agreed fitting an FCU is the better method.

 

[PrenticeBoyofDerry]

It is okay to have the boiler on a plug with a 3A fuse, If I recall correctly the socket that the boiler is plugged into should be one without a switch!
You will need to investigate into the configuration of the circuit to form the ring correctly, this is best done by avoiding any junction/joints but if this unavoidable any junction/joint made that is going to be located in a positions that are inaccessible once work completed, must be made by methods deemed as maintenance free. Also I would guess that amending the configuration into a complete ring, will involve burying new cables within the walls, which will then require to be protected by 30mA RCD!

 

[Taylortwocities]

It is okay to have the boiler on a plug with a 3A fuse, If I recall correctly the socket that the boiler is plugged into should be one without a switch!

EDITED

Generally, the requirement is:


The mains supply to the boiler must be either:
• from a fused double pole isolator situated
next to the appliance. The isolator must
have a minimum of 3mm contact separation
in both poles.
or
• from a plug and non-switched socket
Use a 3A fuse in both situations.

I think the 'non-switched' stipulation is to guard against the socket's switch being only single pole.

 

[ManicInfinity]

Oh damn it

The boiler is just plugged into a standard switched 1G plug socket. So it looks like I'll be replacing the socket with 3A DP FCU.

Understand everything you are saying about the ring. Ideally about 1m would need to be buried in the walls but as it is in the utility room I could surface truck it as I don't really want to be replacing the MCB in the CU with an RCD. This remedial work isn't even supposed to be part of my project.

The place was rewired in 2000 I believe, a few years before I bought it. Why couldn't they have just done it properly then!?

 

[Aragorn84]

Seems odd to me that they'd have rewired in 2000 and not fitted at least one RCD? Either covering the whole board, or a split load affair.

I thaught that was fairly standard fare from early 90's onwards?

 

[ManicInfinity]

My thoughts exactly Aragorn84.

Perhaps it wasn't fully rewired then, but I do know the property was 'renovated' and converted into two maisonettes in 2000 (it used to be a shop) which involved a great of building work, and that the boiler was installed at its present location at this time too. However, based on the amount of remedial work I've had to do it since I bought the place, the conversion was definitely done on the cheap!

Electrically I keep finding non-compliance. For example the spur off the spur issue this topic related to. I also been told the offending 2G socket should be 2 x 1G socket (as the loading from both devices is >13A) with each one connected to a 20A DP switch above the worktop. Is this true?

Further more I've also just noticed that the electric cooker (gas hob) is plugged into a normal socket on the kitchen/utility ring main too. It doesn't go back to it's own MCB on CU which I thought was the norm.

Perhaps "ignorance really is bliss"!? Just kidding - I'm not going to spur to the lean-to until I get the washing machine and drier on the ring-main and solved this unfused spur on a spur issue first.

 

[diyer56]

Sorry I didn't reply with further detail to your questions on my original post - I went to bed I should have used a real diagram rather than the text illustration.

As PBoD explained, I meant this...
View media item 75397

Further more I've also just noticed that the electric cooker (gas hob) is plugged into a normal socket on the kitchen/utility ring main too. It doesn't go back to it's own MCB on CU which I thought was the norm.

If the cooker is designed to be connected via a 13 amp plug then connecting it to a kitchen ring final is acceptable. Some would prefer to run a dedicated radial for this type of connection but it is not a requirement.

However, if the cooker is designed to be connected to a circuit with a higher rating (hard wired) then it should have its own dedicated circuit.

 

[ManicInfinity]

Thank you diyer56.

You, and the rest of the guys who have responded have been extremely helpful, and I shall definitely be correcting this non-compliance issue as you suggest

Depending on the amount of work involved I may keep the existing switched double socket for the washer & drier (but moved onto the ring), unless the regs actually require me to have separate sockets each with a DP isolator above the worktop?

As for the cooker - I will check the installation manual and rating plates shortly, but I think I'm ok.