Re: [CAD_CAM_EDM_DRO] ribbon cable ampacity

Denis,

Finding current capacity for wire this small is difficult. I did find a
table showing maximum current carrying capacity for TFE (Teflon)
insulated wire. Teflon has significantly better temperature tolerance
than the usual gray PVC ribbon cable than connects disk drives.

One rule of AWG (American Wire Gage) wire sizes is that two identical
conductors in parallel have the same current capacity as a wire three
sizes larger (three gage numbers smaller) on the AWG wire table. Thus,
two strands of #28 have the same capacity as one strand of #25 (not that
#25 is a common wire size). 4 strands of #28 would equal one of #22.

Personally, I'd use at least 10 strands of #28 for each conductor to
minimize heating and softening of the insulation. You could always
parallel two strips of ribbon cable to get more conductors.

Another possibility is to find some old SpectraStrip brand Twist-n-Flat
cable. This came in something like #24 or #22 ga. There is also older
rainbow ribbon cable that came in heavy gages. Somewhere around the
basement, I have some 14 Ga mil surplus ribbon, but only about 3 feet of
it.

HTH,
Dave


*Copper Wire TFE Insulated* *AWG* *
Current Carrying

* *AWG* *
Current Carrying

*
*00* 169 *0* 147
*2* 108 *4* 81
*6* 60 *8* 44
*10* 33 *12* 25
*14* 19 *16* 13
*18* 9.2 *20* 6.5
*22* 4.5 *24* 3.3
*26* 2.5 *28* 1.8
*30* 1.3 *-* -


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Denis Casserly wrote:

> Hi Everyone,
> I need a flexible cable assembly between the base and the gantry on my 3 axis
> router and am considering ribbon cable. The bend radius is 1 inch. Is it a
> good idea to use 28 AWG gage ribbon cable for carrying the power and control?
> The stepper drivers will be mounted next to the motors to reduce the noise,
> and they are rated at 3 amp/24 VDC. The rest the conductors would be low
> current step/direction and limit switch wiring. I've tried to find out how
> much current 28 gage will handle - would anyone know.
> cheers,
> Denis