3AUSA21000FG0C Series 300SE - ASCO | Automatic, 1000 AMP

The ASCO Series 300 Service Entrance (SE) version combines the transfer function with a service-entrance rated disconnect in a single listed enclosure, so the switch can be installed at the point where utility power enters the building instead of requiring a separate service disconnect ahead of it. This unit is rated 1000 A, 240V, 2-pole, NEMA 1, open transition. Typical loads are a central plant, a multi-tenant distribution section, a water or wastewater pump station, or a process line — installations where the switch is a free-standing assembly and fault coordination with the service equipment matters as much as the transfer function. The NEMA 1 enclosure is intended for indoor installation in a dry, protected space such as a mechanical room or an electrical closet. Terminations and footprint. Four conductors per pole from 1/0 AWG to 600 kcmil in the 34 in by 72 in by 20 in assembly, 431 to 489 lb. 1,000 A is a whole-building rating — a mid-size office, a clinic, a light manufacturing line — and the switch is engineered around busbar and cable-lug terminations rather than around a single feeder. The neutral assembly on a four-wire system is a full-size bar, not a strap, and it has to be landed with the same care as the phases. Service arrangement. Two-pole 120/240 V single-phase: two ungrounded conductors and a grounded neutral, the arrangement behind nearly every North American dwelling and behind small shops on a split-phase service. Only two poles switch, so a solid-neutral unit carries the grounded conductor straight through while a switched-neutral unit opens it — which is what you want when the generator is treated as a separately derived source and the neutral must be broken to keep the two grounding electrodes apart. Neutral configuration. The grounded conductor is solid: it runs straight through on a bolted neutral plate and is never opened. That is the correct choice when the transfer switch is not a separately derived source — the generator neutral is bonded to the same grounding electrode system as the utility, so the neutral is one continuous current-carrying conductor end to end and breaking it would serve no purpose. It is also the cheaper of the two arrangements and has one fewer set of moving contacts to inspect, which is why it is the default on most commercial retrofits where the existing service neutral is already bonded. Enclosure. The Type 1 cabinet is for indoor use in a dry, protected space — a mechanical room, an electrical closet, a plant room — where the only thing it has to keep out is incidental dust and the occasional touch. It is not rain-tight and not watertight: mounting one on an exterior wall, even under a soffit, invites water in through the door seam and the conduit knockouts, and the first sign is usually a rusted mechanism rather than a tripped breaker. If the switch has to live outdoors, the 3R version of the same rating is the one to order. Service-entrance rating. This is the SE version, which means the assembly is listed as service equipment in its own right: the utility disconnect and the transfer mechanism share one enclosure, and there is no separate main breaker or service disconnect ahead of it. Three things follow from that. The neutral bus is the service neutral and the main bonding jumper lands inside this enclosure, so the grounding electrode conductor terminates here rather than at a separate disconnect. The short-circuit current rating applies to the whole assembly, not just to the switch, and it has to be checked against the available fault current at the service point. And the utility will want to see the listing before they energise it — a standard transfer switch installed ahead of the service disconnect without an SE rating is a common inspection failure. What the extra cost buys is one enclosure, one set of terminations and one less place for a bonding error. Matching generator. At 240V with an 0.8 power factor this switch carries approximately 192 kW of load (1000 A × 240V × 0.8 = 192.0 kW, single-phase two-wire). Size the standby generator so that its standby rating meets or exceeds that figure, and confirm the generator's two-wire automatic-start contacts are compatible with the transfer switch controller. Controller. This unit carries the ASCO Group G controller: a 128 × 64 graphical LCD with switch-position, source-availability, common-alarm and not-in-auto indication. Transfer and re-transfer delays, engine cool-down and the in-phase transfer timer are all set from the membrane keypad rather than from DIP switches, with ranges up to 60 min 59 s. The Group G controller supports both open transition and delayed transition, and accessory 11BE adds RS-485 communication at 9,600–115,200 bps, a seven-period programmable exerciser and a 300-event log. Two-pole configuration. Both the hot and the neutral are switched, which is the normal choice for 120/240 V single-phase residential and light-commercial services and for any circuit derived from a separately derived source. Supply. Supplied as a genuine ASCO Power Technologies (Schneider Electric) unit, brand new and factory original, packed for export from our Dongguan warehouse. Ask us for the outline drawing, wiring diagram and data sheet for this exact catalog number.