Home Wiring

[Badar]

Hi.
The wire i recently used in my home wiring was 7 29 in which 7 represents the Number of wires and 29 for SWG or AWG i think.
Why don't we use one wire of bigger dia instead of using more wires of shorter dia.

 

[Andy1845c]

I'm not following the question.... do you mean you used 7 seperate smaller wires insted of one heavier wire?

Here in america we normally use a single wire of appopriate size for home wiring. I have seen large wire paralleled in industrial settings where the current demands are high and where one wire would be too stiff to pull though conduit.

 

[Hero999]

If I understand rightly, he's asking why wires on house hold appliances are made of many copper strands rather than one big fat conductor.

Cables often use many conductors to make them flexible. Where I live all the stationary wires in my house are single solid core because it's cheaper and they don't need to flex. All portable appliances have multi-strand flexible cables because they're designed to move.

 

[audioguru]

I don't know how electrical wires are connected on the other side of the world, but stranded house wiring in Canada would probably burn at each connection. Our connectors are made for solid wires, not stranded ones.

 

[Styx]

I don't know how electrical wires are connected on the other side of the world, but stranded house wiring in Canada would probably burn at each connection. Our connectors are made for solid wires, not stranded ones.

same here in the UK.

 

[mramos1]

Same here in the US. But I think Hero999 is right on why.

At least we all match up on that part.

We can not on the the AC frequency and voltage, or the side of the road to drive on. But we seem to all be on target here.

 

[Sceadwian]

We use 00 gauge wire at work, not practicle to do that in a single wire, as it's basically bar stock copper at that point.
It couldn't have been normal houshold wireing could it? 7 strands of 29 AWG is roughly the same as a 20 gauge wire isn't it? That's only 3 amps in open air.

 

[Dean Huster]

In industry, most everything runs through conduit, and as such, the wire must be flexible. You'd never be able to pull 12-2+ground romex though conduit. Instead, individual stranded wire is used. Bad connections just because it's stranded? Nah!! Every industrial site in this country would burn to the ground if that were the case!

If you look at a standard wire gauge table designed for electrician, you'll find that wire is available in either stranded or solid conductor until the wire gets to a certain size. Once the wire gets too large, it's only available as stranded or it would be like working with rebar.

Dean

 

[ericgibbs]

I agree with Dean on the points relating to stranded and solid wire usage.

In the UK, domestic interconnection wiring is solid twin and earth.
Commercial premises, in conduit stranded wires are commonly used.

Regarding stranded wiring 'burning out', most domestic heavy duty kitchen
appliances are wired from a 'local' fused isolation switch with flexible stranded cable.

 

[RODALCO]

In New Zealand the TPS wiring in houses is of the stranded type.
1 mm² is solid, 10 Amps max. (lighting)
1.5 mm² is stranded, 3 or 7 strands, 16 Amps max. (lighting)
2.5 mm² is stranded, 7 strands 20, Amps max. (powerpoints)
4 mm² ,, 27 Amps max. (range)
6 mm² ,, 32 Amps max. (range)
10 mm² submains 50 Amps
16 mm² submains 63 Amps
etc.

Connections do not burn up as long these are twisted properly, and folded over prior to inserting in the terminals of sockets and the like.

 

[audioguru]

Here in Canada, 15A home electrical sockets have a hole to push a 14AWG solid wire into. The teeth in the hole grab the wire strongly. There are also screws on the socket that are designed for solid 14AWG wire.
Stranded wire would make hot poor contact with them.

 

[Andy1845c]

Here in Canada, 15A home electrical sockets have a hole to push a 14AWG solid wire into. The teeth in the hole grab the wire strongly. There are also screws on the socket that are designed for solid 14AWG wire.
Stranded wire would make hot poor contact with them.

I've never liked "stab wiring" outlets. I always use the screws.

I suppose you could crimp/solder eyelet terminals onto stranded wire so you could attach it to the screw on an outlet, but that would get to be alot of work.

 

[jbelectric777]

Awg

I think you are working with a stranded 14 AWG (American Gauge) The NEC does not go under size 18 but 14, under conductor properties is 7 strands of 4,110 circular mils or 2.08 sq/mm. You may have purchased the conductor from a company not listing it with the AWG ( I see you are not in the states )
So being 2.08 is so close maybe it was identified as 2.9 , and you read 29. The 7 is the # of strands because thats standard in NEC. That type of conductor usually type THHN/THWN (dual rated these days) single conductor is normally pulled through a raceway of some type. (Codes change country to country ) That may be your electrical code there. Here in the U.S we can use whats called NMB (Romex) in dwellings and some commercial occupancies where the occupancy is not considered a place of assembly (100 persons or more capacity usually determined by the seating capacity,fire marshall or building inspector) The method of connection is a crimp type fork or O terminal which is a wide accepted method of termination other than soldering which is a violation anyway. soldering is a violation because of replacement issues. One thing I can definetly say not to do is try to wrap a stranded conductor around a terminal of any kind. Either use the crimp or adapt to solid and wrap the terminal that way. Good Luck , jb

 

[Dean Huster]

If you arrange six pennies around a seventh, you'll see why there's 7 strands for the smaller gauges.

Dean

 

[Hero999]

Here in Canada, 15A home electrical sockets have a hole to push a 14AWG solid wire into.

What does 15A @ 120V give you? A poxy 1800W, here in the UK we get 13A at 230V which gives you just short of 3kW, enough for a water heater of decent sized electric fire.

 

[audioguru]

My water heater, my fireplace and my furnace burn cheap natural gas. 240V/40A electricity is used for the stove, air-conditioning and clothes dryer.
Everything else uses low power. Most of my light bulbs are 13W compact fluorescent, a few are 23W.

 

[Top Cap]

In the UK we now use all solid conductors but used to use 3/0.29, 7/0.29 and 7/0.36 many years ago.
We use 2.5mm for Power points, these are wired in a ring circuit fused at 30 Amps. Normally 3 ring circuits are provided, one upstairs, one for downstairs and one for the kitchen. Each power point on a ring relies on 13A fused plugs as primary protection but it is up to the consumer to fuse these plugs correctly. Many people do not bother and it is common to find a table lamp with 3A flex being incorrectly fused at 13 Amps. This problem is exasperated by the fact that all new plugs come with a 13A fuse already fitted, in my opinion they should be supplied empty with no fuse.
We use 1.5mm for lighting circuits except for switch drops where 1mm is permissible.
I have seen some installations where 1mm has been used throughout and I am told that this is done because the cable is a bit cheaper
Solid core is much better to work with than stranded, having had experience of both in house wiring.
The regulations seem to be changing all the time over here in the UK, you must be seen to be wearing gloves now when wiring up a power point, glad I am due for retirement, this country is going bonkers!

 

[mneary]

In the US, we don't have fuses at our convenience outlets, nor on the appliance cord (with extremely rare exceptions).

The only overcurrent protection that we use is at the breaker box, where lighting circuits generally have 15A breakers (using 14AWG 1.6 mm), and others (including kitchen) are 20A (12 AWG, 2.0 mm). Higher power appliances have dedicated circuits with different plugs.

The smallest wire I generally see on a lamp is 18 AWG (1 mm). One special case is the tiny Holiday light strings. They have 1A to 3A fuses in their plugs (most people don't even know they're there in their strings).

 

[Styx]

The regulations seem to be changing all the time over here in the UK, you must be seen to be wearing gloves now when wiring up a power point, glad I am due for retirement, this country is going bonkers!

Think its bad at the moment? the sixteenth edition hasn't been out that long and the 17th is soon out. They keep constantly changing aspects of it but still allow electricians to just twist house-wire together and cover in electrical tape (even though pretty good junction box's exist)

You can't even put new sockets in now (well if you happen to have stacks of the old wire you can )

Also the most annoying is they have changed the colours of the power leads!!!!


Home is still the same: Brown=live and Blue=Neutral
but 3ph has got screwed up!!!

no longer Red-Yellow-Blue it is now Brown, black and grey!! I mean that is the even more stupid then trying to change the labels from Red-Yellow-Blue to U-V-W (all EU mandates as well0

RYB is far to useful to use, esp in low-light

 

[mneary]

In the US, all connections must be in a junction box! And all boxes must be accessible (not behind plaster).

I own a house with knob-tube wiring (1890's) and all connections (that I know about) are in junction boxes.