In short: A rain rig puts water over people, cameras and lamps, so the risks are electrical, slippery and wet. This is general guidance only. A competent person must assess the actual rig and the actual shoot. Keep mains supplies out of the wet area, protect circuits with a residual current device, plan drainage and footing, and stop the water before anyone moves onto the floor.
This page is general guidance. It does not replace an assessment of the job you are doing. Someone competent for rigs and for electrics should walk the set, check the supply and agree the plan before the rig is switched on. The points below are the ones a small crew most often forgets.
Keep the electricity away from the water
The water is the main hazard, so the power has to be planned around it. HSE's advice on electrical equipment in damp conditions is to use battery or air-powered tools where you can. Where mains equipment is needed, it can be run at reduced voltage through a centre-tapped-to-earth transformer, which halves the voltage between a live wire and earth.
Protect every circuit in the wet area with a residual current device (RCD). HSE recommends a trip rating of no more than 30 mA. It describes an RCD as a secondary measure, not a replacement for the other controls. Press the test button before each use, and never bypass a unit that trips. A trip means a fault must be found before the circuit is used again.
Keep lamp stands, dimmers and distribution boxes dry and off the floor. Route their cables so they stay out of the path of the water.
Plan the water
- Decide where the water falls, where it drains to and what it will reach.
- Set the rig so it cannot drip onto lamps, cameras or cable joints.
- Check the drainage works before the first run. A catch tray, a sloping floor and a route to a drain or a bucket are the usual answers.
- Fit a shut-off valve on the water supply and agree who turns it off.
- Run the rig with nobody in the water and check every joint for leaks.
Footing and falls
- Cover wet floors with mats or a non-slip surface.
- Tape or cover cables so nobody trips over them.
- Keep a dry route out of the set for performers and crew.
- Keep people off the wet floor unless they need to be there for the shot.
Looking after the people in the rain
Give performers a warm, dry place to change between takes. Plan breaks, and watch for cold, especially on long setups. Agree a plain word that stops the rain before the first take, and make sure everyone on set hears it.
Worked example
A short scene needs rain falling past a doorway. The lamps stay on a separate, protected supply, the drain runs to a tray on the far side of the set, and the floor is matted from the door to the camera. Before the first take the rig runs for a minute with nobody in the water, so the crew can check the joints and the drainage. The rig is switched off, the tray is emptied, and only then do the performers step in.
Common mistakes
- Running an extension lead through the water path.
- Trusting an RCD that has not been tested.
- Starting the rig before the drainage has been checked.
- Placing lamps or cameras where they can drip.
- Having no agreed way to stop the water quickly.
If you want a rain rig built for a shoot, Granary quotes each build, and it is not part of the standard space hire. A rain sequence starts from £750 +VAT, and the quote depends on what you are trying to shoot. For the build itself, see the rain rig build page, and for the shoots, the rain effects filming page.
Sources
- HSE, Work using electrically powered equipment, read 5 November 2026
Related guides
Questions we get asked
How do you stay safe filming rain indoors?
Keep mains supplies out of the wet area, run lamps and tools on a protected or lower-voltage supply, and plan drainage and footing before the first take. A competent person should assess the set before it is used.
What does a residual current device do on a rain rig?
It lowers the risk of electric shock, but HSE describes it as a secondary measure, not a replacement for other controls. HSE gives a tripping current of 30 mA or less, and it must never be bypassed.
Do I need a real rain rig for a rain scene?
Not always. Ask what the shot needs to show. A close shot may need a small effect, while a wide shot needs a rig that covers the whole frame.
granary.digital · 01243 884993 · studio@granary.digital · The Old Grainstore, Adsdean, Chichester, West Sussex, PO18 9DN · Prices exclude VAT unless marked inc VAT