Three phase armoured cable

[JamesHughes]

Can anyone tell me what the appropriate method is here. All the cable I have seen is either 3 or 4 core, not the 5 I assume you would need for 3 phase. Is it usually done by having three cables instead of one? The feed in to the supply box appears to be three or four individual wires twisted up.

It's just me wanting to know out of curiosity, and make sure I dont get ripped off when I get the garage wired up!

James

 

[Lectrician]

4 Core would give 3 phases and a neutral. The earth could be the armour, or an additional cable run along side the armour.

Most 3 phase pieces of kit are designed to run on 3 phases with no neutral connection. In this case, the fourth core can be used as earth.

 

[JamesHughes]

Thanks Lectrician,

I was wondering why no where seemed to sell 5 core!!

I am unfamiliar with regs re: this sort of thing - are the options you give all OK to the regs. I think I would need to used the armour as earth (or separate earth wire), as I need normal 1ph stuff in garage too (Lights, power sockets), which I presume does require a neutral?

James

 

[sm1thson]

is this a domestic 2phase garage?

im not been funny but it looks like you might not really understand what you are doing, yes hence thats why you ask on here but theres a lot more to learn before you start doing what it looks like your going to do.

 

[Lectrician]

Domestic 2 phase Typo

I am guessing you are talking about a submain, and not a final circuit? In that case, yes, you need to run a neutral FOR DEFFINATE!

 

[JamesHughes]

Just to clarify, I have just found out I have a 3 phase supply to my house (See other threads!), which I want to have extended to the garage for power some three phase equipment I have (lathe,mill). The garage has no power supply of any sort at the moment. I just wanted to know what sort of cable was necessary so when I get quoted I know when someone is trying it on!!

I will do all the electricals in the garage myself (lights, sockets from CU onwards), but an not in the right league to put in the supply itself in.

James

 

[sm1thson]

you will want to dig the trench youself if your after saving money!

as for doing the inner electrics yourself this essentially means you are adding new circuits to the submain and it comes under part p of the building regs so it would be better if you got a certificate to cover them for when you sell your house, you can get it certified by the council, but you have to pay and may aswell do the whole job yourself. if you are lucky the spark may sign it off, but there technically not allowed to but some do and given it is in a garage so the cable (presumably) wont be hidden etc you may have a good chance of a spark signing the lot of. (note the spark must be registered or else you will still have to do the whole paying the council thing no matter how many qualifications the spark has)

 

[Lectrician]

And make sure you use metal clad accessories and conduit or SWA in the garage - difficult call to sign it off otherwise!

 

[JamesHughes]

Would I be right in saying that *all* cabling in the garage itself needs to be conduit or SWA? Even stuff feeding the lighting? In the past I have just used T&E as its up in the joists and right out of the way. Also used it to feed sockets though, which is probably a bit naughty. I always use metal clad boxes in garages though.

I don't mind using the conduit/SWA though, just want to know if regs demand it.

James

 

[Steve]

Neat SWA looks the part in a garage.

Or if you like, Mineral Insulated Copper Clad cable looks even better, and blends with the brickwork better. Requires special tools though.

For the 3ph circuits, you'll need to use either 4C SWA or singles in conduits. So it will look better if the whole lot is in conduit or SWA. I think plastic conduit will be fine. Again, metal conduit requires special tools.

 

[Lectrician]

I like to run galv trunking at high level, plastic conduit from trunking up and over to lights. Then decide weather to use galv or plastic conduit drops to sockets / TP isolators etc.

2x2 may be lrge enough for a small garage - run the trunk around all walls, and you can then add things easily.

 

[JamesHughes]

Thanks guys,

most helpful.

Rgds

James