Phase change over box for 40A rotary phase selector switches, 1 way or 3 way — holds the switches that move circuits to a healthy phase.
- Available as 1 way (one selector position) or 3 way (three selector positions).
- Front plate punched for 40A rotary switches — a centre hole with fixing holes at each position.
- Rectangular window above each switch position.
- Knock-outs on the top of the box for cable entry.
- Front plate held by four screws; white finish.
- Switches are sold separately — for example our 40A cam-operated rotary switch.
- Manual phase selection: turn the knob to a healthy phase when one phase fails.
A phase change over box (phase changer box) houses rotary phase selector switches outside the main DB. With a three-phase supply, each selector feeds one circuit or sub-board from phase R, Y or B; when one phase fails or runs low, you turn the knob to a healthy phase and that circuit keeps working.
The front plate is punched for 40A rotary switches, such as our cam-operated rotary switch (positions OFF, 1, 2 and 3), with a rectangular window above each position. Choose 1 way for one switched circuit, or 3 way for three.
It is a switching enclosure only: it does not protect against overload, short circuit or earth leakage, so every circuit must still be protected by an MCB (and an RCCB) in the DB. For a complete board with a selector section built in, see our phase selector DB.
What fits
- 1 way: one 40A rotary phase selector switch.
- 3 way: three 40A rotary phase selector switches — one per switched circuit.
Check the switch's fixing pattern against the plate before wiring, or ask us for a matching switch.
Where to use it
- Homes and shops on a three-phase supply with frequent single-phase failures.
- Keeping essential circuits — lights, fans, fridge, water pump — running during a phase failure.
- Adding phase selection next to an existing DB without replacing it.
How to install
- Switch off the supply and fix the box on the wall near the DB.
- Mount the rotary selector switches on the front plate through the punched holes.
- Wire the three phases to the selector inputs and the circuit to its output, as marked on the switch.
- Keep MCB protection on each circuit, refit the plate and test each position with the load switched off.
Electrical work should be done by a licensed electrician with the supply switched off. Use selector switches that connect a circuit to only one phase at a time.
Frequently asked questions
- What does a phase change over box do?
- It holds rotary phase selector switches, so a circuit fed from a three-phase supply can be moved from a failed phase to a healthy one by turning a knob.
- Is the switch included?
- No. The box is sold empty, as pictured — add a 40A rotary selector switch for each way, such as our cam-operated rotary switch.
- 1 way or 3 way — which do I need?
- One way per circuit you want to switch between phases. A 3 way box takes three switches, for example for lights, sockets and a pump circuit.
- Is it automatic?
- No. It is a manual selector: you turn the switch when a phase fails. It does not protect the circuit — the MCBs and RCCB in your DB do that.
- Is it the same as a generator changeover switch?
- No. A phase selector chooses between the phases of the same supply; a changeover switch chooses between two sources, such as mains and a generator — see our changeover switches.
Buy phase change over boxes online from Electric Market, Chennai. For site, contractor or bulk quantities, contact us for a quote.