Orange cable to old switch in garage - how to replace/treat

[ChristopherB]

I have a single orange wire leading to my garage and conecting to a old metal box containing switch (a big old switch that you pull down with your finger and thumb, not a 'flip' or 'press' thing. With 'Off' or 'On' showing in the white/red part of the switch that is exposed when moving the leaver).

Coming from the metal switch box are 3 'standard' white 2core+earth cables to a double socket and 2 lighting circuits (1 in garage and 1 in potting shed next door)

I am part way through converting garage to a room and have installed 30 plug sockets (I do stage lighting for bands and currently have the lights set up in the garage running from the 1 socket and loads of extension cables so this way they will connect to their own socket). I have also installed new lighting of 16 x 11watt bulbs to replace the single strip light that is currently installed.

The 'new ring main of 30 sockets' and the 'new lighting circuit of 8 lamps' are each simply plugged into the double socket near the metal switch box and now that I know that the wiring is working/ok I want to permanantly connect it to the orange wire and if required replace the metal switch box.


THE QUESTIONS
Do I treat this orange wire as a spur?
Do I need to stepdown for the lighting circuit (5A fuse?)?
Do I treat the 'ring main of 30 sockets' actually as a spur of 30 sockets?

Thanks

 

[systemtek]

You havnt said where the garage feed is supplied from ? Is it a a spur from another socket, is it connected to the consumer unit with its own trip/fuse ? You need to find out where the original garage wire its fed from.

If your going to do it properly, id start again.

So your running 30 sockets from 1 ? Spot the danger.....

 

[ChristopherB]

Point taken re 1 socket to 30 etc etc.

However, the orange cable goes *directly* to a 32A trip switch on the consumer unit.

At the moment, yes, I am going 30 sockets to 1 - yowch even I can see that this is not wise. But when going direct to the orange cable 30 sockets should be ok . . . yes ?

As an additional point, the total load with the stage lights is about 3000watts. A lots for lights, but no more than a 3 bar heater.

(in the past, when using loads of extension cables, they got warm but I have use proper ring main wiring so I believe that this should be ok?

 

[systemtek]

If you have pics of this it would be good to see. The old switch & cable maybe...

If your doing it then if it is old type switches etc like you say it might be best to do a new cable run from the fuse board to the garage. Is the garage attached to the house ? or seperate ?

Is this 30 doubles you have or do you mean 30 in total (15 doubles).

I will sit back and let someone more qualified than i step in with the correct calculations re what you want.

32Amp is standard for a ring, but if its old it may be that the old cable is not up to standard etc etc im sure from what you said about the switch showing the bare connections etc then it might be best to replace it.

Might be worth getting at least a quote from a local recomended spark.

 

[Maxxy]

What size is the 'orange cable'? Is it really hard cable, most likely to be pyro?

If it was me, i would have installed a distribution board in the garage, and then put the sockets into groups, as it sounds like all your gear is low wattage? Worked out what i wanted to run off each group, and then used the appropriate sized circuit breaker, eg 6 amps, per group (with a group on a 16A breaker for running anything which needs more power). Then mark up the sockets to identify the groups. A lot safer than running 30 sockets from a 32Amp breaker, possibly supplied by a radial 2.5mm cable.

The reason your cables were all getting warm is probably because you were pulling more than 32A, but not for a long enough time to burn the fuse out. This is obviously a big fire risk.

Just out of interest, whats your Earth loop impedance value at the metal box?

+++++++++++++++++++++++++++++

Oh and add up all the seperate Wattage values from all the equipment you are running at one time too, and let us know what it is.

 

[ChristopherB]

How do I add an image to my post - can't see the option anywhere. Then I will upload a picture.

The garage is a little way from the house and the orange cable is inside the plasterwork and runs under a paved area - so re running the cable would be a very big job.
The orange cable is run through an extension that was only completed a couple of years ago so *should* be recent cable.

It is 30 sockets (15 doubles).

The switch is not showing any bare connections.

The orange cable is fairly thin (about ths same as lighting flex) and is really tough - not bendy at all - like a solid wire.

WHat would be the point of all the groups - I am not against it just not sure of the point.

How do I work out how many amps I am drawing. The fuse did trip every now and then (when the smoke machine kicks in with an additional 250w the trip would occasional happen).

The cable did not get really HOT, just a bit warm. Howerver the cables were un wound in the open air - the cables are NOW installed in the new stud partitions and wrappped in insulation - is there a fire risk here !?

How do I work out earth loop impedance atthe metal box?

The sumof the wattage values takes us to about 3kW.

Now what ?[/img]

 

[Steve]

That orange cable is MICC - dont mess with it, treated right it will last forever. And the conductors will be surprisingly big for its size.

upload images here: www.imageshack.us

 

[breezer]

Adding pictures to posts is believe it or not in forum information.

I agrree the "orange cable" is a pyro

are these lights DMX controlled?

 

[RF Lighting]

I also have a test rig for stage / theatre in my garage and have run a 16.0mm² 3 core SWA cable to my garage. This gives me a 63A supply to my garage. (approx 15kW)

Virtually every garage I have seen which is fed in MICC, has been either a 2L1 or a 2L1.5 (or imperial equivalent), which will at most allow you 23A (5.5kW)

It is very unlikely that the cable you currently have is capable of carring the power you require, and the 32A MCB it is currently connected to is most likely oversized too. (even 2.5mm² is too small for a 32A MCB), and the fact it is getting warm is an indication that the cable is already overloaded.

Are the socket outlets protected by an RCD?

Are you aware of Part P?

 

[ChristopherB]

Thanks for everyone's advice on this.
No I didn't know about Part P.. . on reading it I guess that this is outside of DIY and will need a sparky to do the work.

I have layed the cable and connected it so it should just be a case of the sparky testing rather than 'doing' thus saving some £.

DMX controlled. Yes the lights are DMX controlled however I am only concerened with getting power to them correctly, not the DMX circuit.

No the individual sockets are not covered by an RCD.

I think that I need to get a sparky to put an RCD consumer unit in the garage and check the total load that I can put on the garage without burning the place down.

By the way, I have insulated the studwalls with rockwool insulation and the cable is in the wall. I have left a 'tunnel' 5cm wide for the cable to run a long to prevent it being squashed by the insulation and allow some heat loss - is this correct ?