Waterproof DC Power Cable Set - 5.5/2.1mm (ADA743)

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Outdoor enthusiasts rejoice! Adafruit now have standard 5.5/2.1mm DC power cable sets in a waterproof variety. These cable sets are ideal for projects that must weather…

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Will these support 100w? (20v 5a)

Hi Benjamin
It is the 5A bit that matters. In the absence of any wire size or stranding details you would have to guess but 5A is not really much.
Will leave it to Core to recommend or not.
cheers Bob

Hi Benjamin and Bob,

I’ve just measured the diameter of the conductors in that cable and they are each 0.6mm and either solid or low-core-count stranded wire (It’s tricky to spot with the ends tinned and cut).
Guides like the AWG standard give very conservative current ratings. As this guide from JST points out there are so many factors that there isn’t one universal table that can tell you the maximum current for a wire since it depends on the insulation material, conductor diameter, ambient temperature, and airflow.

The simple answer is if the wire can take that current without warming up to the point that the insulator integrity would ever be compromised then it’s fine. For my own projects I will supervise the first power-up closely and check that the cable remains at room temperature during the maximum loading conditions, then I know I’ve got enough headroom if there’s ever a particularly warm day, or ventilation changes somewhat.

I’ve used 22AWG wire with 4A current draw successfully before in a household environment. So 5A may be well within reason if the other main factors like ventilation and ambient temperature permit.

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Hi Trent
Does not answer Benjamin’s original question which was “will THESE wires stand 5A”. In the absence of any published (that I could find anyway) information about THESE wires I would think that to be a very valid question.

Not quite so. Many reputable manufacturers (that have been around a lot longer than JST) publish tables which include derating figures for various conditions like free air, bundled, in conduit, bundled in conduit and so on. Usually maximum recommended currents and take into consideration insulation ratings (V85, V105 etc). Most quote voltage drops as V per unit length and current. Also resistance per unit length.
Cheers Bob

Hi Benjamin
Trent has been the only Core representative to give any sort of answer although a bit sketchy. To be sure you would have to measure the diameter of each strand and the number of strands.

Trent, single core should be easy to spot as if you bend it it will stay bent until straightened. Very unlikely to be used in that application where flexing should be assumed.

Benjamin. Using Trents approximation (which probably includes some solder) I would guess (guess being the operative word) on 24AWG or 22AWG. Possibly 26AWG but I don’t think that would be big enough for that application.

Couple of sites with charts for you to look up.

As you can see the 2 charts vary a little bit but for 5A 24AWG or 22AWG are a bit borderline. The second site does give you some de-rating for multiple cores in the same cable which is enlightening. As I mentioned above there are other de-rating conditions but you would have to go to the manufacturers data to find this

So in a nutshell I think 5A for short periods could be OK but for that current long term I personally (and I stress this is only me) would prefer a bit larger cable, particularly if the cable run is several metres. Such a short length might not cause much headache as long as you went a bit larger for longer runs.

You will just have to try it but monitor carefully for a while.

It is still pretty slack that this sort of information (wire size) is not more easily obtainable for this product. Unfortunately this seems to be the norm with this sort of thing these days.
Cheers Bob
Another chart here. This one gives recommended ratings for different insulation temperature ratings. Yes insulation temperature ratings make a difference too. Not all as straight forward as one might think

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Hi Bob, and @Benjamin223277,

Good point, I haven’t cut up a cable to count the strands, but it didn’t hold shape when being bent so it’ll be stranded wire. Most manufacturers usually will mention if something is solid core anyway as it’s an extra feature to brag about.

Detailed wire specifications are often absent from hardware pitched at hobby gear so real-world testing is usually the best bet. In fact barrel jack adaptors also rarely come with a current rating as the more proven specifications and documentation that come with a part, the higher the end price of the part.

Hi Trent

Does the home hobbyist have enough facilities to do “real world testing”. I very much doubt it. So us mortals usually rely on published figures to arrive at a solution as manufacturers usually do have such facilities.

I do see your reasoning but and appreciate the costs involved which have to be passed on but it is a shame and I think a backward step when the end user has to be deprived of what I see as essential planning information just to get something to market cheaper than a competitor. But that is becoming more the rule than exception these days.

If in doubt you could always do what I would normally do and purchase the requires connector and fit my own wires. Problem solved.
Cheers Bob

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