Cable Gland PG Size vs. Metric Size
Two different, mutually incompatible thread sizing systems for cable gland threads: the older PG size (Panzergewinde, designated PG7, PG9, PG11 etc., where the number is not a direct diameter measurement in mm) and the now-common metric size (M12, M16, M20 etc., where the number does indicate the nominal thread diameter in mm). A PG gland and a metric gland with an apparently comparable number (e.g. PG11 and M20) do not simply fit each other's cable-entry opening, and forcing the wrong size compromises the IP sealing of the cable entry. When replacing or extending an existing enclosure, it is therefore essential to first establish which sizing system has been used.
Bij het aanpassen van een oudere schakelkast met PG11-kabelwartels bestelt de monteur bewust vervangende wartels in PG-maat in plaats van de veel vaker voorradige M20-metrische variant, om beschadiging van de doorvoeropening te voorkomen.
Een metrische M20-wartel met kracht in een PG16-opening draaien omdat 'de maten er ongeveer hetzelfde uitzien' — de draadspoed en -diameter verschillen voldoende om de behuizing te beschadigen en de IP-classificatie van de kast teniet te doen.
See also
- → IEC 62444 / EMC Choosing a cable gland — IP rating, strain relief, and EMC shielding
- → IEC TS 60034-25 Motor cable for variable frequency drives — symmetrical construction against bearing currents
- → IEC 60364-5-52 Tab. B.52.21 Cables in thermal insulation — current-carrying capacity per table B.52.21
- → IEC 60364-5-52 (informatief) / EMC Cable screen bonding — single-point or both ends, and why the difference matters
- → IEC 61439-6 Busbar trunking systems (IEC 61439-6) — when to use them instead of cable
- → IEC 60502-1 / NEN 1010 §543.4 Concentric (PEN) cables — the wave-formed concentric conductor as combined neutral-and-earth, and why it is not a shield