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Timers, cables and shelf layout

The lamp is the easy part. The socket, the timer and the lead are what make a shelf safe to leave on while you are out.

One timer for the day length

Decide the hours first. Hours and a dark period has the ranges: often 10–14 hours for foliage, 12–16 for herbs, 14–16 for seedlings, and always a night.

A plug-in timer in the wall socket is the usual arrangement for a bar or a plain bulb. The lamp plugs into the timer. You set it once.

Do not add that timer to a lamp that already has its own timer. The SANSI 10 W clip light listing says the built-in timer is incompatible with smart plugs and external timers, and that it needs resetting after a power cut.

We haven't tested this kit. Specifications are as the maker states them (checked 13 November 2026).

A mechanical timer has little to reset. A digital one keeps a programme if it has a battery, and forgets it if it has not. Either is a better habit than switching the lamp by memory.

Where the lead should and should not go

• Along the back of the shelf, not across the front where you brush it.
• Clear of the glass door, so the door cannot close on it.
• Clear of the sink, the kettle and any tray you water in.
• Clear of the heater on a heat mat. The mat has its own lead. They can share a shelf and they should not share a tangle.

Watering happens. A fitting that is not sold as waterproof should not sit where the watering can drips. The cabinet page has the same warning for bars inside glass. If a lead ever feels warm at a joint, unplug it and stop using that joint.

Extension leads

One extension lead, rated for more than the lamp's wattage, is ordinary. A chain of leads and cube adapters is how people overload a socket with a small lamp and then add a mat, a humidifier and a laptop.

Houseplant lamps in this guide are mostly 10–40 W. That is a small electrical load. The danger is the adaptor pile and a lead trapped under a rug, not the watts of one bar. If the run is long, or you are unsure the lead is up to it, use Plankley's cable-size calculator and read their electrics notes for portable leads. Do not alter fixed house wiring from this page. A cracked socket or a regularly warm plug is an electrician's job.

If you rent, do not drill to hide a cable. The cabinet guide covers clips and permission.

Layout as the plants grow

Leaves grow into the light. Set the indicative gap from the distance guide, then lift the lamp or lower the pot when the plant closes the gap. A shelf with 15 cm of headroom will not keep a 30 cm hanging distance. The shelf tool flags a gap that is tighter than the band for the format it suggests. The fix is a lower-watt fitting or a taller shelf, not a hope that the chart was pessimistic.

Running cost for the hours you just set is in grow light running cost.