Dave;

The IPC design rules have certainly taken this spacing into account. The
IPC-D-275 requires that the designers add a "Standard Fabrication Allowance"
per table 5-10. This table is intended to allow for variation in the
fabrication process. The amount of allowance chosen, should be placed in a
note on the master drawing, flagging the amount to the fabricator,
inspection,  and purchasing.

If the inspection allows breakout beyond the incorporated allowance, then
there could very well be a spacing violation to the nearest conductor.

I mention purchasing, since it is their job to match vendor capabilities with
design requirements. No sense sending a job to a fabricator that is beyond
his normal capability.

Regards,

Gary Ferrari
IPC Staff

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