Electric wire

[jbrain]

I have noticed that when you buy electric copper wire for house installations, that different brands will " look " different in size.

For example you buy 1.5 mm from bangkok cable or you buy the same size wire from another facturer, it may appear thinner in size while on the iinsulation it has the same specifications written.

Therefore I wondered if some manufacturers actually sell a lower size wire as what is written in the spec.

Anyone experiences with this ?

[bankruatsteve]

Are your suggesting there might be companies in Thailand that will cheat and don't worry about regulation?

Good question. I've never noticed difference myself but now that you ask. ??

[jbrain]

I don't want to suggest that it is a fact that companies are cheating in this case, but we all know this is Thailand.

Fact is that the wire from some companies, especially those sold in mom and pop shops, feel thinner than tose from other companies. It may have a different cause, that's why I ask here.

[IMHO]

I have seen 25mm2 that was clearly no bigger than 10mm2, THW 4mm that looked more like 2.5mm.

You're not imagining it

Just stick to Bangkok Cable products if you want to be sure of what you're getting.

[Pib]

Wires with the same size rating (i.e., 25sq/mm, 4sq/mm, 1.5sq/mm etc) which represents the cross-sectional area of the "metal" wire(s) inside the sheathing/insulation can easily look larger or smaller due to the type and thickness of the insulation/sheathing even when meeting the technical specification/some standard printed on the wire. And of course where it's single core or stranded core can also make a difference.

Many different types and thicknesses of PVC and rubbers are used for wire insulation and one PVC/rubber material may need to be a little thicker to match the same specification/rating when compared to another PVC/rubber material. To the naked eye we can't tell what type of PVC/rubber is used in meeting a certain standard/specification....lots of different PVC/rubber compounds out there that may look the same to the naked eye but are night and day different in specs, characteristics, lifespan, etc. This Bangkok Cable document gives some more insight on sheathing/insulation materials.

[IMHO]

Wires with the same size rating (i.e., 25sq/mm, 4sq/mm, 1.5sq/mm etc) which represents the cross-sectional area of the "metal" wire(s) inside the sheathing/insulation can easily look larger or smaller due to the type and thickness of the insulation/sheathing even when meeting the technical specification/some standard printed on the wire. And of course where it's single core or stranded core can also make a difference.

Many different types and thicknesses of PVC and rubbers are used for wire insulation and one PVC/rubber material may need to be a little thicker to match the same specification/rating when compared to another PVC/rubber material. To the naked eye we can't tell what type of PVC/rubber is used in meeting a certain standard/specification....lots of different PVC/rubber compounds out there that may look the same to the naked eye but are night and day different in specs, characteristics, lifespan, etc. This Bangkok Cable document gives some more insight on sheathing/insulation materials.

I'm not talking about the what it looks like with the sheathing on - I'll go down to the worksite scrap pile and see if I can find some of the dodgy stuff and take a photo for you..... when the sun comes up

[Sorridstroker]

If in doubt follow this simple test:

Copper has known resistance values for known CSA and legnth they are documented in tables such as:

http://onlinelibrary.wiley.com/doi/10.1002/9780470998373.app4/pdf

or work out the figure by formula:

http://www.engineeringtoolbox.com/resistance-resisitivity-d_1382.html

check your purchased cable against these figures.

[Sorridstroker]

A 100m legnth of 1.5mm2 copper should have approx 1.133333333ohm resistance.

This does alter with ambient temp.

[Artisi]

A 100m legnth of 1.5mm2 copper should have approx 1.133333333ohm resistance.

This does alter with ambient temp.

Think you forgot to add a few more 3's.

Just pointing the ridicules point of 1.133333333, haven't checked the math involved but any way it would be sufficient to say 1.13 ohm or round it to 1.15, accurate enough for most ohm meters that the average person would have in their toolbox.

[Pib]

Wires with the same size rating (i.e., 25sq/mm, 4sq/mm, 1.5sq/mm etc) which represents the cross-sectional area of the "metal" wire(s) inside the sheathing/insulation can easily look larger or smaller due to the type and thickness of the insulation/sheathing even when meeting the technical specification/some standard printed on the wire. And of course where it's single core or stranded core can also make a difference.

Many different types and thicknesses of PVC and rubbers are used for wire insulation and one PVC/rubber material may need to be a little thicker to match the same specification/rating when compared to another PVC/rubber material. To the naked eye we can't tell what type of PVC/rubber is used in meeting a certain standard/specification....lots of different PVC/rubber compounds out there that may look the same to the naked eye but are night and day different in specs, characteristics, lifespan, etc. This Bangkok Cable document gives some more insight on sheathing/insulation materials.

I'm not talking about the what it looks like with the sheathing on - I'll go down to the worksite scrap pile and see if I can find some of the dodgy stuff and take a photo for you..... when the sun comes up

Probably the two most sold wire brands in Thailand are Thai-Yazaki and Bangkok Cable. Here are two links to a couple of their technical docs which gives specifications for their typical Buildings wire. Thai-Yazaki Link and Bangkok Cable Link.

So we can compare Apples to Apples after opening the documents compare the "THW MEA Type A" wire in both docs which is most likely the wire running in your house walls. To keep it simple just look at the "Nominal Cross Section Area Sqmm" and "Number and Diameter of Wires" columns...the first two columns in each doc for the Type A wire. Basically we are then just comparing the diameter of the copper wire(s) in the insulation...taking the sheathing/insulation out of the picture. And basically I would just look at wire sizes 1, 1.5. 2.5, 4sq/mm and maybe 6 sq/mm as I expect that's the only size you would ever find in your house walls, excluding incoming wires from your electric meter to your consumer unit which would probably be 25sq/mm or 35sq/mm.

You'll will see the diameter of the wires are identical to almost identical between both manufacturers. They are some very minor diameter differences for a couple of the wires but it's like 0.03mm differences which the human eye wouldn't notice....most of the wires diameters are identical between the two manufacturers. But if trying to visually compare the diameter of wire with the installation still on the wire then the eye/brain can be easily fooled.

Also when visually comparing copper wires sizes of the same sq/mm size be sure you are comparing single core to single core or stranded core to stranded core. The stranded core diameter (i.e., bunch of wires twisted together) will be larger than the single core diameter of the same sq/mm rating.

[JungleBiker]

I've read that a domestic power circuit will usually use 2.5 sq.mm. wires and the lighting circuit uses 1.5 sq.mm. wires. I know the thicker wires are more expensive but if I have lots of 2.5 sq.mm. wires leftover - and they're of the right colours - can I safely use them for the lighting circuit?

Thanks.

JB.

[bankruatsteve]

Of course. It will be superfluous but if you have extra - you might as well use it.

[Pib]

I've read that a domestic power circuit will usually use 2.5 sq.mm. wires and the lighting circuit uses 1.5 sq.mm. wires. I know the thicker wires are more expensive but if I have lots of 2.5 sq.mm. wires leftover - and they're of the right colours - can I safely use them for the lighting circuit? Thanks. JB.

Sure...but it's just overkill (amperage-wise) and can be significantly harder to handle/run in some locations since the wire is thicker/stiffer...but if you got it, use it.

[Crossy]

No safety issue using bigger wire than needed, but if you mix sizes in a circuit it's possible that someone in future will think that run of 2.5 is a power circuit and hook a new outlet to it. No issue in itself, but if they then up the 10A breaker to 20A (because the welder opens the 10A), we then have a potential conflagration problem.

[JungleBiker]

No safety issue using bigger wire than needed, but if you mix sizes in a circuit it's possible that someone in future will think that run of 2.5 is a power circuit and hook a new outlet to it. No issue in itself, but if they then up the 10A breaker to 20A (because the welder opens the 10A), we then have a potential conflagration problem.

Thanks everyone.

Good point Crossy, thanks.

JB.