New wall light run off old 30amp supply

[hellopaul2]

Hello,
I am in the process of converting a kitchen into a dining room. I'd like to add a wall light, approximately where the old, now unused, 30 amp cooker supply runs. I was hoping I could use the existing wiring for the light, and change the MCB in the consumer unit to a more suitable (5 amp?) one. I'm assuming there's no problem in doing this? Other than someone in future being very surprised to see such a massive cable running one puny light!

Regarding chasing out the wall (it's brick/plaster) for cable runs, I'd like the switch to be on an adjacent wall. Would it be OK (in terms of accepted practice) to chase out a vertical run a foot or so down from the light, then horizontally, around the corner to the switch?

On this hastily sketched image, the blue is the existing 30amp supply cable, the green would be a new cable to take it across (about 6 inches) to the light, and the red is a new switched loop to the switch:

Untitled

• hellopaul2
• 16 Oct 2014
• 1

The whole room will be replastered in a couple of weeks.

Any thoughts/opinions on this would be greatly appreciated!

Thanks,

Paul

 

[ban-all-sheds]

Would it be OK (in terms of accepted practice) to chase out a vertical run a foot or so down from the light, then horizontally, around the corner to the switch?

No.

On this hastily sketched image, the blue is the existing 30amp supply cable, the green would be a new cable to take it across (about 6 inches) to the light, and the red is a new switched loop to the switch:

The blue isn't allowed to be there either.

//www.diynot.com/wiki/electrics:walls

The cables I've ringed round are OK - the others are not.

Is the circuit RCD protected?

 

[hellopaul2]

Thanks for the quick reply (especially at this time of night!). I have a few more questions...

Why would it be wrong to chase out a vertical run a foot or so down from the light, then horizontally, around the corner to the switch? You've ringed these areas as OK in the sketch.

Would the blue cable be "not OK" because it is not running directly in line with a switch/light/socket? Would it become OK if I rerouted it to be vertically in line with the light fitting? (That's what I've interpreted from the Electrics:walls link you included).

I'm not sure if the circuit is RCD protected...so we can probably assume it's not.

Thanks for taking the time to look at this! (I'm off to bed now).

- Paul[/i]

 

[ekmdgrf]

//www.diynot.com/wiki/Electrics:walls

 

[Taylortwocities]

It may be easier to decommission that 30A feed altogether, and just hook in to the existing lighting circuit.

 

[ericmark]

Not sure about the red cable. Although the pictures show cable zones stopping at corners there is nothing in the wording that says that. "Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear."
The comment "within 150 mm of an angle formed by two adjoining walls or partitions." does tend to point to the idea that a corner means a wall is adjoining and not the same wall.

However in my house the two way strappers for the light in the kitchen were run horizontal and the wall has a dog leg where the extension was slightly narrower than the original kitchen and I made the error of sawing through the wires when fitting the water supply to old fridge. So yes it is dangerous as I certainly did not expect to find a cable there.

However the wiring was passed by the Local Authority Building Control.

 

[ban-all-sheds]

Why would it be wrong to chase out a vertical run a foot or so down from the light, then horizontally, around the corner to the switch? You've ringed these areas as OK in the sketch.

Yes, but I have not ringed around the red part which does not run horizontally from either the light or the switch.

Would the blue cable be "not OK" because it is not running directly in line with a switch/light/socket? Would it become OK if I rerouted it to be vertically in line with the light fitting?

Yes and yes. But at that point, as TTC says, why not put the light on the lighting circuit?

I'm not sure if the circuit is RCD protected...so we can probably assume it's not.

If it's not RCD protected then the Wiring Regulations prohibit the installation of any concealed cables.

 

[ban-all-sheds]

Not sure about the red cable. Although the pictures show cable zones stopping at corners there is nothing in the wording that says that. "Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear."
The comment "within 150 mm of an angle formed by two adjoining walls or partitions." does tend to point to the idea that a corner means a wall is adjoining and not the same wall.

IMO there is no doubt that 522.6.101 (v) says that horizontal zones do not run around corners and only exist in the same wall as the accessories etc which create them.




[POLITE]

Would anybody who wants to discuss how small the corner angle needs to be for there to be two walls please start a new topic.

[/REQUEST]

 

[hellopaul2]

I'll add an RCD to the consumer unit.

The current lighting circuit is nowhere near this proposed light/switch, hence wanting to use what's already right there.

I've read on this forum that running cables behind coving is technically OK, but frowned upon by many people. But it's not like someone's going to bang a nail in it to hang a picture. So I'm now wondering about taking the switched wire straight up from the light, through the coving, then down to the new switch location.

 

[flameport]

So I'm now wondering about taking the switched wire straight up from the light, through the coving, then down to the new switch location.

Yes, that is permitted.
This applies whether the coving is there or not, provided the cables are located within 150mm of the ceiling.
An RCD is still required.

However as this room will be replastered, it would be far better to just put in new cables on the existing lighting circuit and forget bout reusing some old cooker circuit, the cable for which will be far too large to fit into any light fitting.

 

[ericmark]

Not sure about the red cable. Although the pictures show cable zones stopping at corners there is nothing in the wording that says that. "Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear."
The comment "within 150 mm of an angle formed by two adjoining walls or partitions." does tend to point to the idea that a corner means a wall is adjoining and not the same wall.

IMO there is no doubt that 522.6.101 (v) says that horizontal zones do not run around corners and only exist in the same wall as the accessories etc which create them.




[POLITE]

Would anybody who wants to discuss how small the corner angle needs to be for there to be two walls please start a new topic.

[/REQUEST]

Still using old book so 522.6.8 is as high as it goes. So what does 522.6.101 (v) say?

 

[JohnW2]

I'll add an RCD to the consumer unit.

Depending upon what CU you have, that is likely to be easier said than done, and is unlikely to be a DIY job.

Kind Regards, John

 

[JohnW2]

IMO there is no doubt that 522.6.101 (v) says that horizontal zones do not run around corners and only exist in the same wall as the accessories etc which create them.

Still using old book so 522.6.8 is as high as it goes. So what does 522.6.101 (v) say?

I'm not sure what you are referring to here. Both BRB and BGB allow that the 150mm zones at a corner go 'as high as they go', but BAS's point is that neither of the books say that the horizontal safe zone created by an accessory can go around a corner - so only the first 150mm of the horizontal 'red' cable which BAS did not ring would be compliant.

Kind Regards, John

 

[hellopaul2]

I'm sure whoever previously did any kind of wiring in my house had not even read 1.1.1 of the regs!

Not long after we moved in, I noticed the head of one of the screws holding a brass lightswitch was a bit mashed, and I'd occasionally catch my hand on the pointy bits of metal. It wasn't until I noticed that I'd get a similar kind of pain no matter where I touched the plate that I decided to remove it. Lo and behold, someone had connected a live wire to the earthing terminal on the switch plate.

Some time later, I removed another lightswitch (after having switched off the lighting circuit at the consumer unit) only to discover* that one of the wires going to that switch was on a completely different, live (mains) circuit.

*By "discover" I mean get a shock (with all the associated swearing).

Another lightswitch in the ex-kitchen-soon-to-be-dining-room (which this thread is all about) is hanging off the wall due to the complete lack of a box behind it. There is also a cable just cut and left in there. It will be interesting to see if it's live and where it goes! (Obviously I'll "make good" this whole switch when I start working in there next week).

Fun fun fun!

- Paul

 

[hellopaul2]

So assuming that I can and will run the cable through the coving, I could presumably also include a maintenance-free junction box in there, to reduce the 30amp cable to something more suitable.

So the plan would be:

• Remove the bit of 30amp cable running down the wall, so there's just enough coming through the ceiling to connect to.
  Connect this stub of cable to a maintenance-free junction box, behind the coving. (The coving is coming down and being replaced).
  Run a cable vertically down to the light fitting.
  Run a cable around the corner (in the coving) and vertically down to the switch.

OR....
If I went with the suggestions of connecting into the existing lighting circuit, how would be the best way to do this, considering the switch is on the opposite side of the room, and the existing light (to be retained) is in the middle of the ceiling? Run the cables through the coving again? Or up into the ceiling, in the hope that the joists run in the correct direction?