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I’m looking to mount SMT pogo pins on a PCB. The connectors will see a maximum working voltage of 120VDC between any two pins, but only when connected to their corresponding female header.

If the female header is live (120VDC) and the pogo pins only experience 120VDC when connected, what guidelines should I follow for clearance and creepage?

I’m confused because I started off by looking at the distance in air and over a surface between pins, but when these pins are live they will be fully insulated from each other (via the female connector).

I guess my question here is: in general, how is clearance and creepage determined for male headers if power is only supplied by the female socket?

Do no rules have to be followed, or do you need to measure pin-to-pin distance through insulator?

enter image description here

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  • \$\begingroup\$ No sorry, was just including that to show male pins with a female socket. I can change the photo \$\endgroup\$
    – cdubs
    Aug 26, 2021 at 23:18

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Since there is an air gap (on DB9 the gap exists between the conductors on the back, on the pogo pins the gap exists between the pins) you would use creepage and clearance between two conductors for air (not on the PCB).

If between insulators there's usually a different spec for insulators than air. Keep in mind whatever material is between conductors it needs to be rated for the appropriate voltage. Many connectors also have a voltage rating in their spec sheet. It would really depend on the spec at this point and probably the minimum voltage between air or insulator. If for a product in regulatory, they may go off of the datasheet if it has certifications (UL, any ETL)

It said it then depends on the IPC or IEC requirement (or any other requirement) to determine what the minimum gap needs to be for 120 volts.

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  • \$\begingroup\$ Ah ok got it. But why do you measure creepage and clearance through air for the pins of a male connector, if it will only see live voltage when connected to its female header counterpart? \$\endgroup\$
    – cdubs
    Aug 26, 2021 at 23:26
  • \$\begingroup\$ The back side of the shell has no insulation between the pins on either DB-9, even if you heatshrink it, it is difficult to not eliminate the air gap \$\endgroup\$
    – Voltage Spike ♦
    Aug 26, 2021 at 23:28
  • \$\begingroup\$ Oh right, but what about the DIP Socket on an Arduino UNO (for example)? I’m just confused why you have to rate male pins that get covered by a female socket (assuming nothing is exposed on the back like the DB9 connector). \$\endgroup\$
    – cdubs
    Aug 26, 2021 at 23:31
  • \$\begingroup\$ The main concern is electric breakdown and arcing. If either of these occurs it becomes a serious safety problem, arcing can happen through air and insulation. \$\endgroup\$
    – Voltage Spike ♦
    Aug 26, 2021 at 23:33
  • \$\begingroup\$ Yeah that makes sense. I guess I’m just confused why you need to worry about that for male headers like this: \$\endgroup\$
    – cdubs
    Aug 26, 2021 at 23:41

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