Terminal Block Locations of the Power Connections


#1

This is maybe not a KiCad question, but I know that many members here are very knowledgeable.

My design has, essentially, a 15 pin terminal block. There are bus lines (clock and data), analog sensor lines, and of course the two power (V+ and Gnd) input lines.

Anyone have a good reason to locate the power line inputs in any particular section of the long terminal strip?

At first, I think perhaps keeping V+ and Gnd on pin 1 and pin 15 seems like maybe keeping them separate might be a good thing. But, if the wiring uses a 2 conductor pair, stripping that apart down the center to accommodate the distance between pins is probably not a good idea.

After a little bit of thought, I think the power pins should be on one end, and I’m thinking the bottom end of the vertically mounted board. And, I’m thinking the Gnd should be the last pin, pin 15. This way the Gnd fill will be on the board edge and less likely to create a short to chassis ground if the solder mask is compromised.

Experiences, opinions, comments welcome.

Thanks!


#2

I like to put a second Gnd on the third pin so that a short from V+ goes to Gnd, not a signal pin. Someone will always manage to make the connection with the power switched on


#3

Are we talking about a screw-connection terminal block (a.k.a. “barrier block”) or some variant of a pin header?

When using a pin header, I like to consider how much damage might be done if somebody plugs it in wrong-way-around. Or, if somebody plugs in a different, but similar-appearing header that is used elsewhere in the same piece of equipment. (Yes, pin headers are available with shrouds, latches, and keyways intended to prevent this from happening. Some of those features are more effective than others. In the end it’s almost impossible to make the system fool-proof, because we fools are too ingenious!)

Dale


#4

Yes.
It seems like with these that it would not matter where the power connection is.


#5

@davidsrsb has a valid point: somebody who is trying to poke a live power wire into the screw connection may have poor aim, and touch an adjacent terminal. That suggests a ground terminal on BOTH sides of the power terminal may be a wise approach.

Dale


#6

@davidsrsb and @dchisholm,

Thank you both very much for the discussion. The quality replies have helped to further iron out my approach to my current design.

My goal is to achieve that in the design:

1)A misplaced power wire simply blows the supply fuse every time.
2)Adjacent accidentally swapped wires cause malfunction but no damage.

Anyone else have a third goal they attempt to achieve?