Author Topic: Is there a rule of thumb for hole size to wire gauge?  (Read 5093 times)

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Offline peps1Topic starter

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Is there a rule of thumb for hole size to wire gauge?
« on: September 19, 2021, 07:44:47 pm »
Working on a PCB design that is going to need some 16 gauge wire for a couple of pads and was wondering if there was a chart or rule for working out the right hole size to wire gauge ratio?
 

Offline Benta

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Re: Is there a rule of thumb for hole size to wire gauge?
« Reply #1 on: September 19, 2021, 07:54:28 pm »
This question is too nebulous, sorry. Please be more specific.

 

Offline peps1Topic starter

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Re: Is there a rule of thumb for hole size to wire gauge?
« Reply #2 on: September 19, 2021, 08:04:59 pm »
the wire goes into a hole, that hole has to be larger than the cross-sectional dimension of the wire or it won't fit. So is there a standard practice like for example, add 10% of the wires crossectional area for your hole size on the through-hole pad.

Is that less nebulous?
 

Offline Benta

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Re: Is there a rule of thumb for hole size to wire gauge?
« Reply #3 on: September 19, 2021, 08:19:53 pm »
Is that less nebulous?

No.

Stranded? Solid? Isolated? With ferrule? Through-plated hole? Will it be soldered? I could go on...

A distinctive problem formulation before posting is good.

 

Offline floobydust

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Re: Is there a rule of thumb for hole size to wire gauge?
« Reply #4 on: September 19, 2021, 08:36:27 pm »
There's different # strands available in stranded wire. Digi-Key's ruler has "7-strand wire holes" which I find wrong, nobody connects such stiff wire to a PCB, and the holes are way too small i.e. #16 AWG is 1.53mm, #14 1.93mm holes. Who has drill bits that size anyhow?

My notes:
#16AWG, Carol C2065 1.6-1.7mm hole works well and I am going with 1.8mm drill size.
#18AWG, Belden 8522 1.5mm hole works well and I am going with 1.6mm drill size.

I tried math using the advertised OD (for 19-strand wire) then adding say 20% but it doesn't work that good.
Also the insulation thickness varies a lot, so you end up needing almost double the diameter in the end, for your PCB footprint of space.
 

Offline peps1Topic starter

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Re: Is there a rule of thumb for hole size to wire gauge?
« Reply #5 on: September 19, 2021, 09:25:33 pm »
Is that less nebulous?

No.

Stranded? Solid? Isolated? With ferrule? Through-plated hole? Will it be soldered? I could go on...

A distinctive problem formulation before posting is good.

Stranded, Through-plated hole, no ferrule, uninsulated, probably red PTFE sleeving, yes it's going to be soldered (hence mentioning a pad and a hole), 26 x 30AWG stands, 1.326mm² CSA, and please do go on, I would love to learn all the variables that are so important to what I assumed was a simple question, I'm here to learn, and come up with a distinctive problem formulation before posting next time as not to waste anyone time.  :-+


There's different # strands available in stranded wire. Digi-Key's ruler has "7-strand wire holes" which I find wrong, nobody connects such stiff wire to a PCB, and the holes are way too small i.e. #16 AWG is 1.53mm, #14 1.93mm holes. Who has drill bits that size anyhow?

My notes:
#16AWG, Carol C2065 1.6-1.7mm hole works well and I am going with 1.8mm drill size.
#18AWG, Belden 8522 1.5mm hole works well and I am going with 1.6mm drill size.

I tried math using the advertised OD (for 19-strand wire) then adding say 20% but it doesn't work that good.
Also the insulation thickness varies a lot, so you end up needing almost double the diameter in the end, for your PCB footprint of space.

Thank you!
 


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