What an enclosed disconnect switch does
An enclosed disconnect switch (also called a disconnector or isolator switch) provides a visible, lockable means of isolating a circuit or piece of equipment from its power supply for maintenance or emergency shutdown. Unlike a circuit breaker, its job isn't to interrupt fault current automatically — it's a manually operated isolation point, and the "enclosed" part means the switch mechanism sits inside a protective housing rated for the environment it's mounted in, rather than an open panel-mount switch.
Matching current rating and pole configuration
Size the switch's current rating to the full load current of the circuit it isolates, with the same margin discipline used for any protective or isolation device — undersizing risks overheating and contact wear, oversizing is simply cost without benefit. Pole configuration (commonly 2, 3 or 4 pole) has to match the supply configuration: single-phase circuits typically need 2-pole switching (line and neutral), three-phase circuits 3-pole, and installations requiring a switched neutral 4-pole.
Enclosure rating and lockout
The enclosure's IP (or, in North American specifications, NEMA) rating needs to match where the switch is actually mounted — indoor electrical rooms have very different requirements to an outdoor or washdown location. Most enclosed disconnects are designed to accept a padlock in the "off" position, which is the physical basis of lockout/tagout procedures; if your site runs a formal LOTO programme, confirm the specific switch supports the lockout hardware your procedure requires before ordering.