Product Overview
The GE Zenith ZTX series is a compact automatic transfer switch built on a double-throw, mechanically interlocked contactor mechanism: electrically operated and mechanically held, with no solenoid trip to wear out and no neutral position to mis-sequence. The platform covers 30 A to 1,200 A at 200-480 Vac and is listed to UL 1008, CSA and IEC. Zenith Controls was a General Electric business; the ZTX range is now manufactured by ABB and the catalog numbers are unchanged, so a ZTX ordered today is the same switch that has been installed in North American light-commercial buildings for decades. This unit is rated 100 A, 240V, 2-pole, NEMA 3R, open transition. Typical loads are a residential service panel, a small retail or office panelboard, a well pump, a sump pump or a light commercial kitchen β circuits where the entire load can be picked up at once and where a compact wall-mounted enclosure is an advantage. The NEMA 3R enclosure is rain-tight and rated for outdoor mounting against a wall or on a pad, so the switch can sit next to an exterior generator without an additional weather shelter. Terminations and footprint. One conductor per pole, #8 AWG to 3/0 AWG, in the 18 in by 18 in by 8 in enclosure. 100 A is the most common residential service size in North America and this is the switch that matches it: whole-house transfer behind a 20 to 24 kW air-cooled generator, neutral solid, enclosure on the wall beside the meter. Bending space for 3/0 in an 8 in deep box is tight but workable, so long-radius bends are worth planning at rough-in. 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 β 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. Enclosure. The Type 3R cabinet is rain-tight, not watertight: it is built for outdoor mounting against a wall or on a pad, with a hooded or sloped top that sheds water and a gasketed door that keeps driven rain out. What it does not do is keep out dust or hose spray, and the installation still has to do its part β conduit entries need drip loops or sealing hubs so water running down the conduit cannot track into the enclosure, and the mounting surface has to drain. A 3R unit on a north wall in a coastal yard will outlast three indoor units in the same spot, which is why it is the default for anything not under a roof. Matching generator. At 240V with an 0.8 power factor this switch carries approximately 19 kW of load (100 A Γ 240V Γ 0.8 = 19.2 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. Control. The ZTX is supplied with the MX60 microprocessor control panel: undervoltage sensing on Source 1 at 90 % pickup and 80 % dropout, voltage and frequency sensing on Source 2 at 90 % voltage and 95 % frequency pickup, and fixed time delays β engine start 3 s, transfer to generator 15 s, retransfer to utility 5 minutes, engine cool-down 1 minute. The panel carries LEDs for source availability and switch position, pushbuttons for test, exerciser set, timer bypass and program cancel, and a selectable 7 / 14 / 21 / 28-day generator exerciser (factory set to 28 days). All time delays are fixed and not field-adjustable β that is deliberate: the ZTX is aimed at installations where nobody is going to re-commission the switch after the building is handed over. Two-pole switching. Both the hot and the neutral are opened, which is the normal arrangement for 120/240 V single-phase residential and light-commercial services. Supply. Supplied as a genuine GE Zenith Controls (now ABB) ZTX unit, brand new and factory original, packed for export from our Dongguan warehouse. Ask us for the outline drawing, wiring diagram and MX60 control manual for this exact catalog number.
