Description
The OP-DFST is a compact, wall-mounted digital fused-spur timer intended for controlling fixed mains loads from a standard pattress (socket) box. It gives seven-day programming with up to 24 on/off events and an internally linked mains output, and integrates safety features you expect for permanent wiring: a double-pole isolator for safe separation of the load, and a removable BS1362 13 A cartridge fuse in a caddy. In short, it’s a tidy, inexpensive way to schedule a fixed appliance or circuit where you need reliable time control and straightforward protection in a single unit.
Operation is quartz-regulated for reliable timekeeping (typical accuracy ±2.5 seconds per day) and the unit keeps its settings during power cuts using an internal rechargeable cell, quoted at roughly 200 hours of reserve. The electrical capability is primarily for resistive loads — a 13 A resistive rating is quoted, with a lower inductive rating — so it suits things like simple electric heaters, towel rails or domestic circuits that draw steady mains current, and is commonly specified for domestic heating-related circuits.
Key specifications
- Supply: 220–240 V AC, 50 Hz
- Resistive switching rating: 13 A
- Inductive switching rating: 2 A (cos φ 0.6)
- Programme capacity: 24 on/off events across 7 days
- Minimum switching interval: 1 minute
- Backup: internal rechargeable cell (≈200 hours)
- Fuse: BS1362 13 A replaceable cartridge (removable caddy)
- Manual modes: Fixed ON / Timed / Fixed OFF / Random
- Physical: 85 × 85 × 30 mm, 150 g; pattress box mounting; cable outlet / pipe size 30 mm
How it works and typical uses
Mechanically the OP-DFST behaves like other digital fused-spur timers: you fit it into a standard single‑gang pattress or supplied surface-mount box, wire the incoming live, neutral and earth to the marked terminals, and fit the load to the switched side. The timer controls an internally linked mains switch that opens and closes the live and neutral via the integrated double‑pole isolator. That means the load can be completely isolated at the unit for maintenance without relying on an upstream switch.
Because it switches the mains rather than providing a volt‑free contact, you need to confirm whether the appliance or control you intend to operate requires a volt‑free (dry) contact. The OP-DFST is well suited to permanently wired resistive loads such as electric towel rails, immersion heaters (when used within the appliance supplier’s connection requirements), simple heaters, or lighting circuits where a permanently wired timer is acceptable and the load meets the minimum/maximum ratings.
Installation and wiring notes
This is a product for fixed wiring: it should be installed by a suitably qualified electrician in accordance with current wiring regulations. The unit includes four protected screw terminals and a cable outlet intended for a flexible load lead; the removable fuse caddy keeps the cartridge fuse accessible for replacement without having to open the whole unit. The manufacturer’s guidance recommends clearance around the unit and gives a temperature rating suitable for domestic locations (see the specification list below).
Practical installation points to note: the minimum load requirement (100 mA at 240 V) means very low-current electronic loads or some LED control circuits may not be reliably switched. The inductive rating (2 A at power factor 0.6) is low, so motors and heavily inductive loads should be avoided or checked against the appliance manufacturer’s recommendations. There is no IP (ingress protection) rating published for the unit, so do not install it in wet or outdoor locations unless the installer provides suitable protection.
Controls and day‑to‑day use
Programming is typical of small seven-day digital timers: you can set up to 24 individual on/off events across the week and the minimum switching step is one minute, which allows reasonably precise scheduling for daily and weekly patterns. The unit offers manual override options — Fixed ON, Timed, Fixed OFF and a Random mode — so you can temporarily change behaviour without erasing your programmed schedule. A visible display and basic control buttons make day-to-day changes straightforward once you’ve read the brief installer/user instructions.
Practical advantages and limitations
- Advantages: compact, inexpensive, integrates fuse and double‑pole isolation, long battery reserve for settings, suitable for a wide range of domestic fixed wiring applications.
- Limitations: switches mains (not volt‑free), limited inductive rating (2 A), minimum load 100 mA (may fail with very low-draw electronic devices), no listed IP rating — not for exposed outdoor use.
Overall, the OP-DFST is a practical, no‑frills choice when you need a permanently wired timer with built-in isolation and a replaceable fuse in a single pattress-mounted package. It’s most valuable where a tidy, code-compliant installation is required and the load is a simple resistive appliance within the stated amperage limits. As with any fused-spur or switched spur accessory, confirm the details with the appliance manufacturer and use a qualified installer to ensure the circuit and the timer are a safe match for the intended load.
