When is 18AWG possibly not 18AWG?

[Discharged]

I thought I had got my head around this topic - 'AWG'. I believe that means American Wire Gauge.

I bought two lots of cable earlier this year to internal wiring, but no sooner had they both arrived that I noticed the obvious difference:


DSC04656 by Tim Redberry, on Flickr

Yes, one is bigger diameter than the other - the reel says it has a diameter of 1mm, which is true. But the smaller diameter cable on the left is also lablled 18AWG. Why?

It is the one on the left that I am using for my work. It is used with 240v to power a microcontroller and to make connections on the controller. Would there be any harm in using the larger diameter cable?

As for AWG, my understanding is that the lower the number, the thicker the cable. ie, 16AWG is larger than 18AWG.

Thoughts appreciated.

 

[Specialist]

Is it due to different outer insulation type & thickness ?

 

[telectrix]

bit difficult to tell from the photo, but does 1 have thicker insulation? the AWG refers only to the conductor size, not the overall size.

 

[Discharged]

You know, I never thought of that. Here's the wire stripped (in haste, with a carving knife!)


DSC04657 by Tim Redberry, on Flickr

Ok, so what is the reason for the thicker insulation?

 

[ipf]

How long's a piece of wire?:speechless:

 

[Specialist]

Different insulating properties of the covering used.

Take a look at the cable section on www.cpc.co.uk & it shows the differences in insulation thicknesses.

 

[telectrix]

so the conductors are the same gauge, n'est pas?

 

[Engineer54]

The Yanks have many types of cable, all with varying insulation thicknesses, types of insulation and heat resistance grades etc... you need to check the code type printed on the cable.

Yes the thicker/bigger the cable size, the lower the AWG figure...

 

[Discharged]

I don't have my Vernier gauge with me up here, but they certainly appear to be. Not something I was expecting.

 

[GLENNSPARK]

it may have something to do with the imperial measurments the americans still use,.....like the old BSP sizes were measured on the BORE wheres metric is on the o/d.......

 

[Specialist]

I don't have my Vernier gauge with me up here, but they certainly appear to be. Not something I was expecting.

As they're both 18AWG, the only thing you need to think about really is: Is the insulation on both suitable for what you want to use them for ?

 

[Engineer54]

So is the yank system based on O/D, and why there 3/4 and 1'' for argument's sake, is that much larger than ours conduits....

 

[GLENNSPARK]

well eng.....i am going by british......and british pipe sizes were on the bore......so lets say a 3/4" pipe fot instance so thats about 19mm yes.......you measure the o/d though eng.....more like just short of 22mm.........but will be sold as 3/4".......

 

[GLENNSPARK]

its why BSP taps and dies etc...can seem strange as they allow for the wall thickness see..........

 

[cook1e]

we buy a fair bit of belden and belden equivalent, when i looked into it in terms of volt drop and distance etc, i was amazed at the different metric conversions, off the top of my head it was down to 0.85 up to 1 mm, depends who you buy from seemingly. but all seems to fit the awg standard - try googling awg equivalents