The Fox ESS EPS Box Pro is a three-phase whole-home backup gateway that keeps your household running through a grid outage, working alongside your AIO-H3, H3, H3 Smart, P3-S, H3 Pro or P3 Pro inverter. It houses an automatic transfer switch (ATS), breakers and a smart meter inside a single wall-mounted enclosure, so the whole property switches from grid to stored solar power in under three seconds when the mains supply fails.
Rated at 63A per phase, the EPS Box Pro is built for full three-phase installations rather than single-circuit backup, giving compatible Fox ESS hybrid systems genuine whole-home emergency power. The robust metal enclosure carries an IP65 rating, allowing it to be sited outdoors as well as in a plant room or garage, alongside the inverter and battery stack.
63 A
Max Input/Output (Per Phase)
< 3 sec
Automatic Switchover Time
IP65
Ingress Protection
16 kg
Net Weight
550 x 420 x 138.5 mm
Dimensions (W x H x D)
-25°C to +60°C
Operating Temperature
Confirm Inverter Compatibility
The EPS Box Pro is an auxiliary product for Fox ESS three-phase inverters and is compatible with the AIO-H3, H3, H3 Smart, P3-S, H3 Pro and P3 Pro ranges. It is not designed for single-phase installations - check your inverter model before ordering, and note that the standard EPS Box Pro includes a built-in smart meter, while the EPS Box Pro-G variant does not.
Automatic or Manual Switching
The internal automatic transfer switch defaults to manual mode out of the box. If automatic changeover is required, the dual power transfer switch must be set to automatic mode during commissioning by the installer.
Qualified Installer Required
Installation, wiring and earthing must be carried out by a qualified, authorised electrician in line with the manufacturer's installation manual and current wiring regulations. The utility supply and load circuits must not exceed 63A when the grid is operating normally, and installation must avoid direct sunlight, high humidity, and locations above 2000m altitude.
Whole-Home Backup
Integrates a smart meter, breaker and automatic transfer switch in one enclosure, giving full three-phase properties genuine whole-home power during an outage rather than backing up a single circuit.
Under 3-Second Switchover
Automatically transfers the load to the inverter's EPS (reserve) terminal in under three seconds when the grid fails, and switches back to the grid automatically once supply is restored.
Multi-Inverter Compatibility
Works with the AIO-H3, H3, H3 Smart, P3-S, H3 Pro and P3 Pro three-phase inverter ranges, giving flexibility across current and legacy Fox ESS three-phase systems.
Weatherproof IP65 Enclosure
A robust metal, IP65-rated housing allows the unit to be wall-mounted outdoors as well as indoors, alongside the inverter and battery installation.
Built-In Smart Meter
Includes an internal RS-485 smart meter for accurate monitoring of grid and backup power flow (the EPS Box Pro-G variant omits the meter for simpler installations).
Wide Operating Range
Rated to operate from -25°C to +60°C (with derating above 45°C), suiting a broad range of UK plant room and outdoor installation conditions.
General
Model
EPS Box Pro
Type
Three-phase automatic transfer switch / backup gateway
Compatible Inverters
AIO-H3, H3, H3 Smart, P3-S, H3 Pro, P3 Pro
Communication Interface
RS-485 (Meter)
Switchover Time
< 3 seconds
Switching Mode
Automatic or manual (default: manual)
Utility Supply
Rated Voltage
220/380 VAC, 230/400 VAC, 3L/N/PE
Rated Frequency
50/60 Hz
Max. Input Current (Per Phase)
63 A
Inverter Grid
Rated Voltage
220/380 VAC, 230/400 VAC, 3L/N/PE
Rated Frequency
50/60 Hz
Max. Input Current (Per Phase)
25 A
Inverter EPS
Rated Voltage
220/380 VAC, 230/400 VAC, 3L/N/PE
Rated Frequency
50/60 Hz
Max. Input Current (Per Phase)
25 A
Load Output
Rated Voltage
220/380 VAC, 230/400 VAC, 3L/N/PE
Rated Frequency
50/60 Hz
Max. Output Current (Per Phase)
63 A
General Data
Cooling Concept
Natural convection
Installation
Wall-mounted
Operating Temperature Range
-25°C to +60°C (derating above 45°C)
Dimensions (W x H x D)
550 x 420 x 138.5 mm
Packing Dimensions (W x H x D)
665 x 515 x 235 mm
Net Weight
16 kg
Gross Weight
19.27 kg
Ingress Protection
IP65
EAN Not Yet Confirmed
An EAN/barcode for this SKU could not be confirmed from an authoritative manufacturer or distributor source at the time of writing and has therefore been omitted rather than estimated.
Which Fox ESS inverters does the EPS Box Pro work with?
It is designed as an auxiliary product for the AIO-H3, H3, H3 Smart, P3-S, H3 Pro and P3 Pro three-phase inverter ranges. It is not intended for single-phase Fox ESS systems.
How quickly does it switch to backup power during a power cut?
The automatic transfer switch changes the load over to the inverter's EPS (reserve) terminal in under 3 seconds, and switches back to the grid automatically once normal supply is restored.
Does it need to be set to automatic mode, or is that the default?
The unit ships in manual mode by default. An installer must set the internal dual power transfer switch to automatic mode during commissioning if automatic changeover is required.
What's the difference between the EPS Box Pro and EPS Box Pro-G?
They share identical electrical specifications and dimensions. The standard EPS Box Pro includes a built-in RS-485 smart meter, while the EPS Box Pro-G omits the meter for a simpler, unmetered installation.
Can this be installed outdoors?
Yes. The enclosure carries an IP65 rating and is rated for operation from -25°C to +60°C (with derating above 45°C), though installation must still avoid direct sunlight, precipitation and high humidity, and be carried out by a qualified electrician.
Will it power my whole house during a blackout?
It is designed to support whole-home backup on a three-phase supply, subject to the load on each phase staying within the connected inverter's off-grid output capacity - oversized loads during an outage may not run normally.
