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I'm looking at a (relatively popular) slip ring which uses AWG28 wires and has a rated current of 2A/channel. However, this chart suggests that AWG28 is only capable of carrying 0.226A for power transmission. How is it safe to use AWG28 for carrying 2A?

EDIT1: Similarly, this slip ring from Adafruit, which uses AWG26, appears to exceed current ratings (2A).

EDIT2: As @DKNguyen pointed out, Moog uses similar gauges.

John M.
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    [What to check for when buying an electronic component or module](https://electronics.stackexchange.com/questions/504044/what-to-check-for-when-buying-an-electronic-component-or-module). Without a data sheet, who would trust it especially as it is sourced from aliexpress? – Andy aka Jun 19 '20 at 12:40
  • Probably not safe, if it's like a factor 10 above the capabilities of AWG28. But it depends if the current is continuously 2A or you use some duty cycle or signals, and the ambient temperature/cooling. – Michel Keijzers Jun 19 '20 at 12:42
  • @Andyaka I've found [this slip ring from Adafruit](https://cdn-shop.adafruit.com/datasheets/SRC022A-6.pdf) which uses AWG26 with a 2A rating. But AWG26 power transmission rating is just 0.361A. – John M. Jun 19 '20 at 14:00
  • Sorry, I misread your question. I thought you asked "how safe is it?" when you asked "how is it safe?" – DKNguyen Jun 19 '20 at 14:01
  • @MichelKeijzers I thought Adafruit would have more reliable products. But am I reading the AWG correctly? "Maximum amps for chassis wiring" gives higher current ratings. That seems to be the reading for wiring 'in air' rather than 'in bundle', but wires in a slip ring are in a bundle to some extent. – John M. Jun 19 '20 at 14:04
  • I looked up reputable slip rings from Moog and they are the same but they use Teflon insulation. Most wiring tables are for lesser insulation like PVC unless otherwise stated and many tables are for a specified rise above ambient, not running to the very limit of the insulation. At Teflon's 200C limit, 28AWG is listed as 6A then add 0.7 derating for a 6-15 bundle. – DKNguyen Jun 19 '20 at 14:09
  • @JohnM. I'm not familiar with slip rings myself, but normally it's best to keep the safest value... I also would say a slip ring behaves more like a bundle than a single wire. – Michel Keijzers Jun 19 '20 at 14:12
  • In your table, I think chassis wiring is current/heat limited while power transmission is voltage drop limited but it is a bit vague since tolerable voltage drop is dependant on length and operating voltage none of which have been specified in the table. – DKNguyen Jun 19 '20 at 14:16
  • @JohnM. in my link about the data sheet in my top comment, point 2 said: "Make sure you have the latest data sheet." - so, given that there appears to be no indication on the data sheet who the manufacturer is or where they are based, you cannot check to see if you have the latest data sheet - this disqualifies that product from consideration in my opinion. Also, does the so-called data sheet provide any clear wiring information and, does it (largely) leave no stone unturned? I don't think so from what I saw. Don't use it is my advice. – Andy aka Jun 19 '20 at 14:21
  • @Andyaka Please see my second edit regarding [Moog's slip rings](https://www.moog.com/content/dam/moog/literature/MCG/SlipringProdguide.pdf) some of which use AWG28 for 2A, e.g., AC7188. – John M. Jun 19 '20 at 14:25
  • @JohnM. I would trust Moog but that link is more of a brochure and I would want a more detailed PDF datasheet for the item I was considering buying and maybe those are available from Moog (I'm not going to look BTW). And because Moog are Moog and eminently contactable, I would just contact them and ask for the specific data sheet and wiring information and, expect to get it. How would you do that with the cowboys? – Andy aka Jun 19 '20 at 14:30
  • So, I just looked for the Moog SRA-73683 and found [this data sheet](https://www.moog.com/content/dam/moog/literature/MCG/SRA-73683.pdf) and it all comes together with Moog and is believable. It says `2 A, per ring, max.` and it says 26 AWG Teflon® insulated and not 28 AWG - buy Moog is my advice. – Andy aka Jun 19 '20 at 14:35

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