A few small questions :)

[Philip657]

Sorry is some of these seem simple to people.

my first thing how to people work out the diversity on a ring main? and how many sockets would be max that people put on a ring as a rule of thumb ?


i have looked at a property this week and they have a water feature wired in twin and earth unprotected in the ground. i have got the work to rewire it with SWA. i have never used the swa before anyone got an hints and tips ? were i bring in throw the wall hows best to terminate it? i don't want to run it up the wall and terminate at the switch ?

i am just channelling for a ring main in my house most cables i have managed to get down 20mm and steal capped them but i have one brick wall that is engineed brings and i can only get plaster depth ( same as my steal capping) is this ok i know its not ideal but is it within regs ?


Thanks for all replys Phil

 

[malcolmsanford]

There is no real diversity that can be applied to ring final circuits as such, so a good guide to area, how many etc for socket outlets is the OSG guide in appendix 8 page 137

Steel Wire Armoured (SWA) Cable - Wikipedia, the free encyclopedia

This is an excellent guide to terminating SWA if you have never done this before. As for bringing it through the wall make sure you drill an hole large enough, try and drill so that you can get a good sweep on the cable to go through the wall.

Regulation 522.6.6 and 522.6.7 for the cable, it would need by the looks of things to be RCD protected

 

[Des 56]

i don't want to run it up the wall and terminate at the switch ?


You could terminate the swa externally in a weatherproof box and convert it in there to T+E for the shallow depth on the inner wall

 

[Electricalserv]

Put the ring on 30mA rcd..... SWA must be 600mm deep ????? (correct if wrong) then terminate into weatherproof box, the T&E to switch as mentioned.

 

[Philip657]

Thanks all the curcuits on a are on 345 RCD's i

600 deap in a dig-able area 500 deap on a non dig-able area and a spade deapth for temp supplys as long as there marked

its ok to change swa at the wall to twin and earth ? is there any special requirements to take in regarding the earth as the earth on the swa is a core and the armour ?

thanks for the link


Phil

 

[sjm]

I thought it was a minimum of 450mm deep but less is OK if not likely to be disturbed. Unless you're Western Power, in which case just under the surface will be fine and don't worry about that caution tape nonsense. I kid you not, saw it last week at a customers house where they put a new supply in to a neighbours.

 

[mike2790]

how many sockets would be max that people put on a ring as a rule of thumb ?

generally i wire 10 sockets to a ring but the good book says you can have any number of sockets on the same ring as long as the area the ring covers does not exceed 100m2, obviously common sense comes into play with that though.

 

[Amp David]

I have always used a number or 10 for kitchens and 15 for oyther areas.

Don't know why though

 

[Paul.M]

As above common sense has to prevail. What are the sockets going to be used for? How many watts? Etc. Worst case scenario is Christmas day with everything in the kitchen on + the tv + the new games console + all the lights in the house on + someone having a shower to go out for a late Xmas party. If your circuits can stand up to that, you've got it just right.

 

[Philip657]

yea i have wired 10 doubles on one ring in the office do to the amount of high power appliances. but in the main house i was thinking maybe about 20 due to i think they will be for things like a lamp, kitchen tv, kitchen appliances and sockets in the dinning room for the odd things that needs to be pluged in. as logic tells me that i am not going to use them all at once but when i come to see i am not sure the uses people will use the sockets for and they may pull full load on all socket.

 

[kathwilcox]

in a house i would have 3 separate rings 1 up, 1 down, 1 for kitchen, then there's no chance of overload and if there's a problem with 1 circuit then there's still power else where, as for the swa i would as others have stated terminate into IP rated adaptable box outside with t&e through the wall from inside, i would use 3 core swa as then you have a protected earth and don't have to rely on your glands being spot on as this is you first time using the cable. not a lot to it you will be fine.

 

[nickblake]

Under ground cables are required to be at a depth of 600mm and you should use marker tape , when installing SWa under ground they should be laid on a bed of sand then the cable laid then covered in sand then marker tape then back filled till the trench is almost full then another marker tape then covered this way you know the cables there earlier rather than later easier for marker tapes than to repair a damaged cable

 

[telectrix]

and pvc tube the T/E through the wall to give it protection.

 

[kathwilcox]

also before you put the lid on the IP box put some silicone in the hole through the wall and over the screw heads stops any moisture and creepy crawlies causing problems in the future

 

[daveede]

Hey

Im new to electrics but i was talking to someone about diversity a few days ago and the answer is in the onsite guide.

Edit:

Got the osg from the van, take a look at page 97

Appears to be 100% of highest demand load + 40% of all other loads