IPC-2221
Generic Standard on Printed Board Design
The foundational standard for printed-board design, covering conductor sizing, electrical spacing and general layout. Its trace-current formula, derived from mid-century test data, is the conservative method most calculators use to size trace width.
Source: IPC. Verify against the current edition.
IPC-2152
Determining Current-Carrying Capacity
The modern, test-based standard for a conductor's current-carrying capacity. It accounts for board material, thickness and nearby copper planes, and generally allows narrower traces than IPC-2221 for the same current and temperature rise.
Source: IPC. Verify against the current edition.
IEC 60529
Degrees of Protection Provided by Enclosures (IP Code)
Defines the IP code, the two-digit rating for how well an enclosure resists solids, dust and water. The first digit covers solid objects and dust (0 to 6), the second covers water (0 to 9).
Source: IEC. Verify against the current edition.
NEMA 250 / UL 50E
Enclosures for Electrical Equipment
The North American enclosure Type ratings (1, 3R, 4X, 12 and so on). They cover ingress like the IP code, but add tests for corrosion, external ice and oil, which is why they cross-reference to IP ratings one way only.
Source: NEMA. Verify against the current edition.
IEC 62368-1
The hazard-based safety standard for AV, IT and communication equipment. It replaced IEC 60950-1 and IEC 60065 in December 2020 and classifies energy sources as ES1, ES2 or ES3, applying safeguards that scale with the class.
Source: IEC. Verify against the current edition.
UL 62368-1
The binational UL/CSA adoption of IEC 62368-1 for the US and Canada, with the same hazard-based model plus national differences. Effective from December 2020, replacing UL 60950-1 and UL 60065.
Source: UL. Verify against the current edition.
IEC 61010-1
The general safety standard for test, measurement, process-control and laboratory equipment - defined by function rather than industry. Current as the 3rd edition with Amendment 1, it introduces measurement categories CAT II to IV.
Source: IEC. Verify against the current edition.
UL 94
The flammability screening standard for plastics in electronic parts, classifying materials from HB up to 5VA by how they self-extinguish and whether they drip. The material group it informs feeds directly into creepage design.
Source: UL. Verify against the current edition.