Power not propagated across connectors

How can I get power to propagate across a connector?

For example, a 7805 output is designated as ‘power output’, and pin 14 of a 4000-series IC is designated ‘power input’. Connect them together directly and ERC is happy.

But put a connector between them and ERC complains, presumably because the connector pins are designated ‘passive’. The only answer seems to be to put a POWER_FLAG on the net between the connector and the IC pin 14.

I did find a comment on post 6 of an old thread from 2015

" found a solution, but it is kind of confusing and not really logical in my opinion: Power pins on supply symbols must be configured as invisible otherwise they won’t work. This isn’t a usual problem I guess because the standard supply symbols do of cause stick to that rule but I did some experiments and broke that rule. With the corrected symbols in use it does work now."

but without the actual schematics (links no longer work) I couldn’t make sense of that.


This is not true (at least not in KiCad 5, maybe it was true a long time ago)

The PWR_FLAG method is the official recommended solution to this problem (besides the other option of just ignoring that ERC check or disabling it)

Thanks, I was guessing that would be the answer. The other option was to create custom connectors with power in & out pins but that’s just worse IMHO.

Can you tell a bit more about your intentions?

Using connectors to connect stuff implies that you have multiple PCB’s and want to connect them either with PCB to PCB connectors or with cables, but it would be a multi PCB project anyway.

As far as I know the “official” KiCad PCB is one PCB for one project.

Some time ago I did an experiment by linking multiple one-pcb project together in a hierarchical “master” project, and it seemed to work quite well.

The link (with downloadable project files) is here:

A more recent discussion about this is here:

It is a bit of work to set up such a project but I think the Idea is quite good, and I’ve seen somewhere between 5 and 10 requests for multi-pcb projects pass by on this forum. I’m sort of curious if this Idea could get some “official” support in KiCad. With some minor tweaks to KiCad’s Project Manager you could start with the “Master Project” and then create sub projects, and maybe use another color as the hierarchical sheet for such sub projects.

@paulvdh Yes I saw your thread on that and was toying with the idea of reworking my schematic, but I decided that wasn’t necessary. The schematic is a 14 sheet documentation of some 20y old equipment that the manufacturer won’t release schematics for, even though they haven’t manufactured it for nearly 8y. In order to repair it I decided to do a full tear down and document it as the fault traversed at least two of the three PCB. As it happens the connector issue arose because there is a removable jumper to allow connection of an ammeter into a power line during calibration and I was using a standard 2-pin header to represent that. There is no intent to create the PCBs from this schematic so the ERC wasn’t critical, but was just a good check to ensure I’d not left anything dangling!

You can use labels on the connectors to connect them together.
This of course makes real netlist connections between the different PCB’s, and therefore completes the ERC check. Just add a note to remove some of the wire labels if you ever decide to make the PCB’s themselves.

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