Re: wire question - another question AMPS

> The logic of this is when you are trying
> to get the lowest induced noise
> in a piece of equipment, such as audio,
> telephone or measurement instruments.
> However, if you are trying to exclude strong
> interfering signals, or prevent radiation
> from wires in the cable, then a continuous
> shield from the housing of box A to the
> housing of box B often works better.
> This is one of those black arts where there
> actually are no hard and fast rules, just general
> guidelines.

In this case, I plan on grounding the cable(s) at the gantry end, and
the cable will protrude into the power supply enclosure. I will
assume some benefit from shielding as the enclosure and cable are in
close proximity with little more than the insulation as the gap
between them.

Since I have the 110AC, the transformer, Gecko's and breakout board
in the same enclosure I'm not terribly concerned with noises between
the units once it gets into the enclosure.


The new question is AMP RATING of stepper cables. 1.7V 4.5A steppers
running at about 36 volts.

Normal Average Amp Capacity based on 500 circular mils per Amp

This would indicate that an 18 ga wire would handle 3.2485 amps.
And a 16 ga wire would handle 5.1654 amps.

Does the wire need to be rated for the full continuous amp rating or
can one just de-rate the wire by 50% ?

50% would be the assumed value of any wire in the bundle on a stepper
as being at full amps for any speed as the duty cycle is 50% at
maximum on any single coil.

Since I'm wiring to about 20 feet, and resistance reaches 1 ohm at
150 ft for the 18ga and 250ft for the 16 ga, I'm not overly worried
about overloading the wire based on wire length.


Dave