Seemingly Out of Spec AC Cables Could Be a Fire Hazard

Subject: General Tech | February 23, 2015 - 03:31 PM |
Tagged: Vantec, c13

I say “seemingly out of spec” because I am not an electrician, and this requires more understanding of wire classifications than I possess. Regardless, we found a story a little while ago about devices that ship with power cables that are labeled for voltages and amperages that are significantly lower than what they are capable of carrying.

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My cable

The minimum requirement for cables with a C13 connector is American 18 gauge (AWG), and they must be able to carry 10 amps. I own the device from the blog posting, like many others at PC Perspective. Again, the device itself (minus the cord that plugs it into the wall) is perfectly fine. The allegation is that the power cord (that goes between the wall and the transformer power brick) cannot carry its full, labeled wattage. The head claims that it can carry 250V at 10A, which is 2500W.

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My cable, close up.

We cut open the insides of the cable to see what gauge wire was used, and we were able to remove the insulation with an 18 gauge wire stripper. This is where my lack of applied electrical skills fail me. The power cable feels as flimsy as a quarter-inch audio cable, but I am not qualified to measure the actual internal wires' thickness. It might meet the minimum (18 AWG) requirements, or it might just be thick insulation. I wouldn't trust it, especially not at hundreds or thousands of watts. The blog post author apparently tested their own cable under load, and they claim that it started to melt at 2.6A 123V (320W).

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The blog author's wire vs a standard cable's wire. It's hard to tell how thin the Vantec one is, because the standard cable was twisted.

Image Credit: Fry's Acid Test

Now, to power a single hard drive and USB controller, you are not going to be drawing those hundreds or thousands of watts from the wall. The main concern is if you swap cables around with other devices. For instance, if that cable would be attached to a high-end gaming desktop, then it could easily see wattages in that range that are sustained for most of a play session, or even higher.

So I guess the takeaway from this is do not trust every power cables that you receive. Make sure your high-power devices are using the cable that came with them, or one from a vendor that you trust. Just because it says it can handle any given load, does not mean that it can.

February 23, 2015 | 04:43 PM - Posted by Anonymous (not verified)

This is why most people stay away from gimicky looking products from no-name manufacturers. They put even less time and money into their products as well established companies who have their parts made in Cheap Asia.

If it's one thing you shouldn't skimp on it's power delivery. This is how those stupid knock off wall chargers for a phone burn down your whole damn house.

February 23, 2015 | 04:52 PM - Posted by Anonymous (not verified)

Hell, My Samsung laptop does not even have the Samsung Brand on the power brick, luckily my other 3 laptops have names on the power bricks, so I can keep the factory supplied plug matched to the device, and I never detach the plugs from the brick, it's always best to read the rating on the plug, and hope it is not from some questionable source. Even the OEMs are having to do recalls, if they do not stay on top of their QA.

PCs have bigger power needs but still if the plug is getting hot, its best to double check the rating on the plug, there are aftermarket suppliers of power plugs, and maybe some articles on replacing/repairing the plug, or moving up to a little heavier gauge replacement plug would help, the maximum load placed on the plug should never be the maximum of the spec, looking at Wikipedia the max temp on the plug should be 70 °C, after that there is the electric kettle type plug C15/C16 coupler at 120 °C, It's always good to double check the rated voltage, and amperage on the plug itself and compare it to what the device draws.
It looks like they may need a C13A/C14A standard for those gaming rigs with a little more Voltage/amperage/temp headroom. It would be nice if they could ship plugs with an added visual temperature gauge, maybe added to the plug by the OEM, and not the plug's supplier, for an extra layer of safety, for sure there have been recalls on some laptops, and PCs.

February 23, 2015 | 05:20 PM - Posted by Alexander12 (not verified)

I have read into the story and the blog you are refering to.

You are making major errors.

The power adapter can support 34W in totoal (thats what the label says). Because the harddrive does not need much power this is more than enought. The hard drive will take the power it needs, which is much less.

The claiming about 10A and 2500W is wrong. Dont mix input with output voltage. No power adapter this size can support that.
The power adapter is rated for max. 34W Output in total. It has two readings 24W(Ausgang: 12V 2000mA) and a second rating for 10W (Output 5V 2000mA). (May also be different ratings for US and Germany as well.)

For 34W however the cables dont need to be big inside. Think of a smartphone power adapter it is very small as well. It just needs to charge the smartphone. Or think of a laptop who needs much more power than a single harddrive.

Why do i know this things? Its my profession.

February 23, 2015 | 05:40 PM - Posted by Scott Michaud

First: it's not the adapter. The adapter is fine. It's the cable. If you attach that C13 cable to something high power like a computer, because it is labeled 250V 10A and has a C13 connector, then you might have a lot of problems.

The device it came with will probably not draw anywhere near enough wattage to matter... if you don't accidentally get the cables mixed up. That is what I'm saying, and that is what the blog said.

I did not make any major errors, at least not in that regard.

February 23, 2015 | 05:34 PM - Posted by Alexander12 (not verified)

To i get you right?
Yes, the cable is not suited for very high voltage. Does it need to be in america? Perhaps.
However it should totally work fine with the device it came with. And that is what the blog post (the link was refering to) was unsure about.

February 23, 2015 | 05:44 PM - Posted by Scott Michaud

The problem is if later you: disconnect the cable, put it in the closet, pull it out, read its label, assume it can support up to 10A @ 250V because that's what it says it can, and plug it into something else that uses hundreds of watts.

With the device it comes with, it should be fine. I would destroy it and get a better one, though, if only because you might lose it later and get it mixed up with other ones. (Edit Feb 24th: Although obviously "should be fine" still means "if you have this, get a new power cable for it anyway, just in case". At this point, we established that the cable supplier seems to be dishonest.)

February 24, 2015 | 05:54 AM - Posted by Alexander12 (not verified)

I agree with you in terms of the cable.
The written label is not right that is a no go.

Therefore i wonder why the manufacturerer did not choose a different plug design (where there are no such high regulations) AND label it correctly?

The result for me is the same. Dont trust a supplier with makes false claims.

February 23, 2015 | 07:55 PM - Posted by Klem (not verified)

The determination of AWG for stranded wire is the total cross sectional area of the conductors. For 18AWG this is .823mm^2. Take a micometer measure a single conductor use a little PiR^2 and multiply it by the number of conductors. You have your answer. Oddly enough the AWG of a wire may not be the determining factor in its safe current carrying capabilities, not all wire is 100% copper and wire of higher resistance will have less capacity and heat faster than copper. Though I don't think it matters much at 120VAC.

February 23, 2015 | 08:12 PM - Posted by Scott Michaud

Thanks for the advice!

February 23, 2015 | 09:00 PM - Posted by Lala (not verified)

This happened to me when I bought a 12v transformer for a LED strip from Aliexpress. The power cable has a standard computer supply IEC connector. It looked thinner than usual, but thought nothing of it.

About two months later, my led strip started flashing and I heard a strange popping noise coming from the cable or transformer I didn't know which.

Thankfully I was in the room at the time, and quickly turned it off. On closer inspection the cord closest to the transformer end had melted, caused a short and burnt through the insulation and outer sheath.

I looked up the cable and found it was not meant suited for a 240v 10A situation, with the cable cross section being about a quarter of what it should have been. I never thought a 12v 8a supply would draw that much anyway, but this cable was in no way suited for the purpose.

Altering the seller was a waste of time.
I've learned my lesson now. You get what you pay for. Skimping on price nearly cost me my house.

February 23, 2015 | 10:29 PM - Posted by Tim Verry

Wow, I'm glad that you are okay and were able to disconnect it in time!

February 24, 2015 | 03:07 AM - Posted by Lala (not verified)

The transformer was tucked out of the way beside a bed. So it could have been a real fire hazard.

It worked fine afterwards*. It just needed a power cable bought in country.

I think this proves that some products from China although attractive price wise are made with the cheapest components possible and because they sell directly to the public they don't have to worry about strict quality control or a supplier refusing to pay for a shipment because of shoddy workmanship.

* About six months later the transformer started making a LOUD ticking noise. It's now being punished by sitting in a box and thinking about what it's done!

February 24, 2015 | 04:42 PM - Posted by Bill (not verified)

This problem is more widespread than you might think. Recently I was looking around for a 10' power cord to go from my computer to the outlet on the other side of my computer desk. The 6' cable that came with my PSU isn't long enough to reach. I went to Amazon, searched for "10' power cord", and the first one that came up apparently has a big problem with overheating and is a fire hazard.

What's strange is the cord is rated for 10 amps at 120 volts, but people that used them for powering even low power computers noticed the cord was burning hot. Some have stated that the cord seems to have problems with anything over 2 amps, which is far lower than it's rated 10 amp capacity. The best way to tell what kind of power the cord will carry is it's size.

February 25, 2015 | 02:03 PM - Posted by ButtonPuncher (not verified)

Mislabeling the AWG on the cable is criminal. That's how fires get started. If it's stamped 18AWG and it's actually 24AWG, that's a massive difference in current capacity. The quick way to determine what gauge it is is to see what hole in the wire stripper that the CONDUCTORS fit in to. The insulation has nothing to do with the AWG.

Also, like another review said, you just can't multiple the max voltage and max current to get what the cable can handle. you multiple the max current times the working voltage. So even though the cable is stamped 10V @250V, at 120V, it will only carry 1200W. 10x120.

Do an internet search for "ampacity table" and you will get the NEC (national electric code) ratings for wires.

BTW, length also affects the power handling capability. A 1 foot piece of 24AWG might be able to handle 10A. But a 100' extension cord needs to be 18AWG to handle the same current.

February 25, 2015 | 11:26 PM - Posted by Scott Michaud

Correct. In North America, it would only see ~1200W and it wouldn't plug into a European outlet, unless you use a travel adapter without a transformer.

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