Maximum current in a ribbon cable "strand"?

Other Hardware General Electronics
1

I'm trying to find out how much a single "strand" in a ribbon cable can carry. By "strand" I mean the red strand or the green strand in a multicolour ribbon cable. An example of the product: Multicolour ribbon cable

This link: Ribbon Cable Current Rating seems to suggest that it is 2.2A.

(I look at the table: AWG wire sizes used in flat ribbon cable, the 26AWG row.)

Out of no actual knowledge, but 2.2A seems high to me.

The application needs to drive 12 solenoids which consume 1.2A at 12V per solenoid. Usually only one solenoid will be driven at a time. Each will be activated for less than a second.

2

Current ratings are really thermal ratings. Temperature rise in the conductor can reach a point where the insulation is damaged. Temperature rise is not instantaneous of course.
Ratings are normally specified for worst case conditions.

In your case, if you have a duty cycle that is some small percentage of 100% then you probably can achieve the max rating easily. That is assuming that the ambient temp is in a typical range, and not enclosed in a cabinet which might reach 70C.

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3

I agree but add that you have to also consider voltage drop and whether the voltage drop is acceptable for the application. Do you know Ohms law?

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4

Be aware, some "QWORK" branded cable from AE/AMZ can be whatever, even strands made of steel.
You should measure the resistance.

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5

Rule of thumb solution to both temperature rise and voltage drop:

You are powering a solenoid, which is a coil made from a long thin wire. Being a coil concentrates the heat in a small space. If you use a supply wire that is much shorter and a bit thicker than the wire the coil is made from then it will be fine.

If the temperature rise in the coil is okay then the rise in the wire will be less so will be ok too.

If the supply wire is short in comparison to the length of wire in the solenoid then it will make little difference to the current supplied to the solenoid.

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6

You need to know
The voltage
The diameter of the cable
The material (Al, Cu...)
The Length
And the maximum allowed voltage drop.

With these values you can calculate the maximum current.

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7

And there is a formula which have these as input and max current as output?

8

That's a good point, thanks.

But no the solenoids will be at the about 1 meter from the Arduino + driving transistors.

9

You mean that the 2.2A on that WEB page is probably true, and anyway, on average with pulsed 1.2A, I'll get nowhere near that?

10

Arg. I'll check before I buy. Thanks.

11

Again, I had not thought about that. Thanks. I'll measure the resistence over the distance I intend to use.

12

I do.

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13

may be this helps you:

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14

Many thanks for that.