MDF Contactors — Heavy-Duty Grow Light Relay Control Without the Premium Price
Best for: Growers running multiple high-wattage lights who need reliable power control without melting their timer to bits
Our thoughts
Here's the thing: a standard timer cannot handle the load from HID grow lights. It will fail. MDF Contactors solve that problem properly, and they do it at a price that doesn't require a second mortgage. Assembled in the UK, built on industrial-grade Grasslin mechanics, these boards give you the control and safety of professional-grade kit at entry-to-mid tier pricing.
An MDF contactor board is your insurance policy against timer failure. When you're running high-wattage grow lights, a standard time-switch will arc out and fail within months — sometimes leaving your light stuck in the on position, which can wreck flowering plants in hours. A contactor relay absorbs the electrical load and lets your timer do its actual job: timing. MDF Contactors give you multiple switched sockets, integrated Grasslin timers, and individual on/off control for each appliance, all mounted on a wall-mountable board. It's the central hub that stops chaos and protects your plants.
How it compares
MDF Contactors sit in the smart value tier of grow room power management.
- Same industry-standard Grasslin timer and contactor reliability as premium brands
- MDF board construction keeps costs down without compromising electrical performance
- Full 40amp contactor protection — identical spec to metal-housed competitors
- UK assembled, same as market leaders, with none of the brand markup
Maxibright and LUMii offer metal housings and extended warranties at 2–3x the price. If you need the contactor to work reliably (you do), this does exactly that for less.
Usage guidance
MDF Contactors work across different grow room setups:
Multiple HID lights
Each socket has its own individual on/off switch. Wire your ballasts to separate sockets, set the integrated timer once, and each light switches automatically on your schedule. No more timer meltdown.
Mixed appliance control
Use switched sockets for lights and fans, keep "always on" sockets for heaters and essential kit. Label as you go — keeps wiring tidy and prevents accidental shutdowns.
Setup and mounting
Wall-mount using the corner fixing points on the MDF board, or stand on a shelf if you prefer. Rubber moulded plugs and hanging brackets make installation straightforward. Keep it accessible so you can manually override if needed.
Why this matters
A contactor absorbs the electrical surge from switching high-load equipment. Your timer sits downstream, protected, and actually lasts. Without one, timer failure is inevitable.
Technical specifications
- Board construction: MDF backing, wall-mountable with corner fixings
- Integrated contactors: Two 40amp relays
- Protection: 40amp breaker fuse
- Timer: Grasslin 24-hour mechanical (industry standard)
- Socket capacity: Safely handles 6–26 UK mains plugs depending on model
- Always-on sockets: Two 24-hour constant double sockets (for non-timed equipment)
- Plugs: Rubber moulded, switchable sockets
- Typical board dimensions: 600 x 300mm (4–8 way models)
- Available configurations: 2-way, 4-way, 6-way, 8-way
- Maximum load: 3000W at 13 amps per side
Who this is for
- Growers running 2 or more high-wattage HID lights in one space
- Anyone using a standard timer now who's worried it'll fail (it will)
- Growers who want centralised, organised power control without mess
- Budget-conscious setups where professional-grade reliability is non-negotiable
- Anyone who's had a timer die mid-grow and doesn't want it to happen again
Our take
A contactor isn't optional when you're running serious lighting. It's a one-off investment that stops your timer from dying and your plants from getting fried. MDF Contactors deliver exactly that at a price that makes sense.
We bought heavy on these because they work and they're priced right. If you're building a multi-light setup or replacing failed kit, worth picking up while clearance stock lasts. Does exactly what it should — protects your kit and your plants, day in, day out.
