The Dangers Of Cheap Power Cables

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2 minutes ago, Cinnabar Sonar said:

Now I feel like an idiot...  

Speaking of that, I circled them in the wrong colour... red and blue need to be swapped on one end  

[Skanky Sylveon]

Just now, Ryan_Vickers said:

Speaking of that, I circled them in the wrong colour... red and blue need to be swapped on one end  

Red is hot right?

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Just now, Cinnabar Sonar said:

Red is hot right?

I didn't mean the colours to actually mean anything, just trying to show which wire went to what and messed it up anyway  

[Skanky Sylveon]

1 minute ago, Ryan_Vickers said:

I didn't mean the colours to actually mean anything, just trying to show which wire went to what and messed it up anyway  

We all goof up sometimes.  

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Just now, Cinnabar Sonar said:

We all goof up sometimes.  

But yes, the smaller one is "hot", and here's another fun fact.  All electrical outlets are installed upside down.  The ground is supposed to be on top so that if a stray wire falls across the ends of a plug that's not fully inserted, it just goes to ground rather than bridging the hot and neutral, shorting it out.  When installed sideways, the hot is supposed to be nearest the floor for this reason, but again I also see them installed upside down in this way on occasion.

It may also have the added benefit of making the plug not look like a face, although I suppose we should be happy they chose to make the "mouth" ground in the event someone does try to feed it...

[Skanky Sylveon]

3 minutes ago, Ryan_Vickers said:

But yes, the smaller one is "hot", and here's another fun fact.  All electrical outlets are installed upside down.  The ground is supposed to be on top so that if a stray wire falls across the ends of a plug that's not fully inserted, it just goes to ground rather than bridging the hot and neutral, shorting it out.  When installed sideways, the hot is supposed to be nearest the floor for this reason, but again I also see them installed upside down in this way on occasion.

It may also have the added benefit of making the plug not look like a face, although I suppose we should be happy they chose to make the "mouth" ground in the event someone does try to feed it...

A sad face...

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Just now, Cinnabar Sonar said:

A sad face...

I think we could learn a lot from the british plugs.  While I feel that wiring it yourself is strange and would never work in the US, we could at least adopt elements of the plug.  For example, the fact that ground makes contact before the other two, and the fact that the powered leads are shielded so it is impossible for the plug to be powered, and for your hands to be on the powered metal bits simultaneously.

[mariushm]

edit : 6 more posts while composing this...

 

UK has the outlets nicely made with polarity and earth pin goes only one way but across Europe you have the classic Shuko plugs which have the earth on either side, so you can plug something in an outlet either way

You can't rely on Live being always to the left, and neutral always to the right and so on...

 

In UK they had to be aware of polarity because of how they wired their houses after the war, and because a lot of devices they were buying had only one fuse because fuses were expensive, so the fuse had to be on the live wire for safety

 

The UK plugs are really well designed but they're a bitch when you step on them.

 

I was talking below about a post where you posted a picture with the plug and made colored circles on the pins of the plug :

 

^ the green circled one may often have different resistance value since it's just for safety, could be different diameter or different number of strands.

Only the Live and Neutral wires (red and blue) carry energy, those matter.

 

i was composing a long reply while above replies were posted... this was what i was typing

 

You can use a basic multimeter ...

Put the meter on resistance mode and use one probe on the plug side that goes in the power outlet and the other in the part that goes into your device. 

 

Really, for a mains cable, the resistance of a wire should be less than 1-2 ohms in my opinion.

 

Even AWG18 (what you find in power supplies) has a 1mm diameter and  0.75..0.8mm² area (for the copper inside, excluding insulation) and has around 21 mOhm per meter of cable, so a 2-3 meter mains cable would mean there's 4-6 meters of cable in total between mains socket and the device should have less than 0.1 ohms of resistance.

At 110v 15A, that's P = I²R = 225 x 4 meters x 0.021 ohm = 19 watts dissipated across 4 meters of wire.

 

Here in Europe or at least where I am, 1.5mm thick stranded cables are very common, I think those would be kinda comparable to AWG15 .. AWG 16 and those are at around 10 mOhm per meter.  Here's an example of a datasheet for such cable : http://www.farnell.com/datasheets/1965984.pdf  - as you can see, a 1.5mm cable is rated for 15A and has 13mOhm per meter resistance, typical for AWG16.

 

 

If the power cable is not removable... it's a bit more difficult but not impossible.

 

You could start my measuring the power pulled from the mains socket for example using a power monitor like kill-a-watt , or maybe using a current clamp meter to measure the current flowing through the mains wires, or  by placing the multimeter on current measurement in series with the circuit (but this last option is s dangerous if you don't know what you're doing)

Then at the same time you could measure the temperature of the cable before you turn on the device and let's say 30 minutes or 1 hour of operation.

 

If you know how much the cables warmed up you can sort of estimate how much power was lost in the cable because you have the length of cable, you have the number of cables, heat will vary with resistance of the wire etc...

 

 

 

 

 

 

 

[Skanky Sylveon]

5 minutes ago, Ryan_Vickers said:

I think we could learn a lot from the british plugs.  While I feel that wiring it yourself is strange and would never work in the US, we could at least adopt elements of the plug.  For example, the fact that ground makes contact before the other two, and the fact that the powered leads are shielded so it is impossible for the plug to be powered, and for your hands to be on the powered metal bits simultaneously.

British power is 220 right?

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Just now, Cinnabar Sonar said:

British power is 220 right?

That too

[mariushm]

The whole Europe is supposed to be 230v +/- 10% or something like that.

 

So basically that makes it legal for some countries to be as low as 210v and some as high as 250v.

 

In some areas of UK you may have 220v, in others you may have 230v

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1 minute ago, mariushm said:

The whole Europe is supposed to be 230v +/- 10% or something like that.

 

So basically that makes it legal for some countries to be as low as 210v and some as high as 250v.

 

In some areas of UK you may have 220v, in others you may have 230v

By and large it's roughly double what we have here is the point

[Skanky Sylveon]

Just now, Ryan_Vickers said:

That too

I have shocked myself by accidentally touching the metal while plugging it in.  Not pleasant.

It would have sucked even more if America uses 220.

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Just now, Cinnabar Sonar said:

I have shocked myself by accidentally touching the metal while plugging it in.  Not pleasant.

It would have sucked even more if America uses 220.

I'm not sure about that actually.  One of the things I've heard is that 120 can cause your muscles to seize, keeping you holding on to the plug and getting fried, while 220 is so powerful it triggers them all to convulse and launch you away from it... idk if that's really true, it sounds a little weird to me, but if it is, we really should switch.  Not to mention most devices are more efficient when using 220 anyway (see PC PSUs).  Not that I actually expect NA to switch plugs or voltage, that would be insane, but it would be probably good if they did.

[Skanky Sylveon]

1 minute ago, Ryan_Vickers said:

I'm not sure about that actually.  One of the things I've heard is that 120 can cause your muscles to seize, keeping you holding on to the plug and getting fried, while 220 is so powerful it triggers them all to convulse and launch you away from it... idk if that's really true, it sounds a little weird to me, but if it is, we really should switch.  Not to mention most devices are more efficient when using 220 anyway (see PC PSUs).  Not that I actually expect NA to switch plugs or voltage, that would be insane, but it would be probably good if they did.

At this point, it would be insane.  

The muscles that are directly touching the metal do seize a little bit, but not to the point where you have no control.  Also, all of your other muscles still work just fine, so I don't see a problem with someone getting away, as long as they are not wrapped in the cable.

[mariushm]

A lot of switching power supplies have a tiny capacitor between the mains side and the secondary side of the power supply, which is there to reduce the EMI (the noise) caused by the transformer and the other components inside the power supply, all that "switching" is not good for radios and other things. 

 

The downside is that you can be shocked if you touched the dc jack of a power supply but the current is so small and the capacitor holds so little charge that it's not a health risk (usually, if the capacitor is sized properly, some Chinese psus just use what they have and non safety rated capacitors).  So for some power supplies regardless of operating at 110v or 220v, you'd still be just as much shocked , the capacitor will hold the same charge.

 

See https://electronics.stackexchange.com/questions/216959/what-does-the-y-capacitor-in-a-smps-do

 

I used to get shocked a lot when plugging analogue TV cable in my TV tuner.. it wasn't fun.

Also got a few zaps during the times of networks made with BNC cables (coaxial cables, 10mbps, before ethernet), and computers with bad earthing.

 

[Skanky Sylveon]

2 minutes ago, mariushm said:

A lot of switching power supplies have a tiny capacitor between the mains side and the secondary side of the power supply, which is there to reduce the EMI (the noise) caused by the transformer and the other components inside the power supply, all that "switching" is not good for radios and other things. 

 

The downside is that you can be shocked if you touched the dc jack of a power supply but the current is so small and the capacitor holds so little charge that it's not a health risk (usually, if the capacitor is sized properly, some Chinese psus just use what they have and non safety rated capacitors).  So for some power supplies regardless of operating at 110v or 220v, you'd still be just as much shocked , the capacitor will hold the same charge.

Interesting, I guess that is just another reason to not skimp on your power supply.

3 minutes ago, mariushm said:

I used to get shocked a lot when plugging analogue TV cable in my TV tuner.. it wasn't fun.

Also got a few zaps during the times of networks made with BNC cables (coaxial cables, 10mbps, before ethernet), and computers with bad earthing.

Fun times.  Electricity doesn't feel good going through you.

[iamdarkyoshi]

I ran it until it blew up. Both ends caught fire and left burns on my workbench. The wires were glowing red hot.

 

One of the wires eventually melted on this end, which I guess makes it a fuse lol

[Mihle]

The reason why aluminium cables is used when the the cables is thicker than a specific thickness (Might depend on the country, but in my country, copper is used up to 16mm2 and above that its aluminium, normally) is because the extra cost and weight of copper isnt worth it even if it has less resistance. And for cables that goes trough the air, Aluminium is better at holding up its own weight than copper, aka, you can have longer cables between each point.

And, US plug is one of the worst ones. Its both worse than the UK and the European one. Of the UK and European one, meh, they are both really good compared to a lot of other plugs.
And btw, The Tom Scott video, most of what he say is true with the European plug too, well, done in a different way ofc.

The main benefit of 230v vs 120v is ofc that on 230v, you can have thinner cables, and that makes it cheaper.
Many parts in Europe (Not UK and most places not my country, In UK I believe its to the first neighbourhood splitter box thing (I dont know what its called)) There are 400v 3 phase in to the fusebox in the house, and from there its live + neutral going to different places of the house.

[mariushm]

Yeah, my parents' apartment has aluminum cables going to the lights in each room - the cables are thick and a bit flattened (they're not round)

The apartment is in a 4 story building in the center of the town made before during the communist regime in my country, a few years before the 1990 revolution.

 

Even though it was made a bit more high end compared to other apartment buildings it still had those cheaper cables for lightning (we were "lucky" my father was working as a chemist at an institute in town and my mother was a teacher, so since they both had good jobs they were allowed to buy that apartment)

The building had proper copper cables for mains sockets and they bothered to install proper circuit breaker boxes and other "luxury" things for that time

 

In UK a lot of houses weren't wired in the typical "star" fashion, meaning wires going from a point to each room, in a lot of places they tried to save on copper and other metals by making a ring of wire throughout the house. Because of this, if one device failed shorted, it could take out the whole house by burning the wires inside the walls... so that's why you see the fuses in mains plugs in UK ... usually you find 10A fuses or some ridiculously high fuse values in the plugs... they're main purpose was not to protect you the user, but to protect the house from burning up.

Most devices had additional fuses inside them with the proper rating.