Do electric rooflights need an electrician?

Mains yes, solar no, and that is most of the answer

Two supply arrangements cover almost every electrically operated rooflight sold in this country. A mains unit takes a fixed 230V connection, either directly at the head of the window with the low voltage electronics inside the sash, or through a control unit sited in the loft that is itself fed at 230V. Either way, a circuit in the house is being extended or added to, and that is electrical work in a dwelling.

A solar unit takes nothing. A small photovoltaic panel on the outside of the top rail charges a rechargeable battery inside the sash, and the same chain actuator, rain sensor and radio receiver run off that battery. Nothing is wired back to the house. That is not a compromise product, and in a finished loft room or a listed roof it is frequently the better specification for reasons that have nothing to do with avoiding an electrician. It just happens to remove the question.

Part P, and where notifiable work begins

Electrical work in a dwelling is covered by Part P of the Building Regulations, and adding a new circuit is notifiable under it where applicable. Whether a particular job is notifiable depends on what is being done: a new circuit from the consumer unit falls inside it, while some alterations to an existing circuit sit outside the notification requirement but still have to meet the wiring standard and still have to be tested.

On a rooflight job the notification rarely stands alone in any case. Forming a new opening in a roof is notifiable work for structural and thermal reasons already, so a Building Control application is being made for the installation regardless. The electrical element is dealt with within that same process, the inspection is booked, and the completion certificate comes back in the homeowner’s name. Doing it this way keeps one file rather than two, which matters at the point of sale when a buyer’s solicitor asks for the paperwork.

The certificate, and why it belongs in the handover pack

Testing produces a document. It records the circuit, the protective device, the earthing arrangement and the test results, and it is signed by the person who carried out the work. That document is not a formality, and it is the thing that is missing when a homeowner discovers, fifteen years later, that a previous owner had a window motorised by somebody who came and went.

On a Severn job the electrical certificate goes into the pack alongside the Building Control completion certificate, the manufacturer’s warranty documents for the unit and its motor, the model and size codes, the remote pairing instructions, and a written note of where the supply comes from and where the isolator is. That last item is worth more than it sounds. A power supply above a plasterboard ceiling with no hatch and no record of its position is a problem waiting for its moment.

Low voltage control wiring, which is a different piece of work

A good deal of what looks like wiring on an electric rooflight is not mains at all. A wired wall pad on a cable back to the control unit, the link between a control unit and a second window on the same slope, a hard wired rain sensor on a kerb mounted unit: these carry a few volts and they are part of the manufacturer’s system rather than the house installation.

That work is done by whoever is fitting the unit, following the manufacturer’s wiring diagram, and it is commissioned by cycling the sash and testing the sensor with actual water rather than assuming. It still wants planning at first fix, because a wired wall pad by the door of a loft room needs its cable run before the plasterboard goes on, and a low voltage cable retro-fitted into a finished slope is exactly as disruptive as a mains one. That is a sequencing question rather than a regulatory one.

Solar operation, which takes the supply out of the job

In three Gloucestershire situations the solar route is chosen for the building rather than for the wiring, and the absence of an electrical trade is a side effect.

The first is a finished loft room. Plastered slopes, decorated walls, a fitted wardrobe under the window: getting a cable to the head of that frame means opening the reveal, replastering and redecorating, and a solar unit avoids all three.

The second is a listed building, which central Cheltenham has in quantity. Consent covers work nobody outside will ever see, and chasing a cable into original lath and lime plaster is precisely that kind of work. The third is a Cotswold cottage roof through Painswick or Chipping Campden, where the slope is lime plastered internally and the roof is torched from below, and every additional route through the fabric is another conversation with the conservation officer. Solar removes it.

Sequencing: who is on site, and in what order

On a mains job the order matters more than the people. The structural opening is formed and trimmed, the unit is set and flashed, and the roof is closed. The cable is run at first fix while the reveal is open: along the side of a rafter, clear of the 25mm ventilation gap above the insulation, and through the vapour control layer at a purpose made grommet or a taped collar. Insulation and the vapour layer go in tight to the frame, the reveal is boarded and plastered, and only then does the final connection happen at second fix.

Get that sequence wrong and the alternatives are all worse: a cable surface run in trunking across a finished reveal, or plasterboard lifted a fortnight after it went up. The electrical attendance is therefore two short visits rather than one, planned at survey, and the date for each is on the programme before the scaffold goes up.

Older Gloucestershire wiring, and what the survey looks at

A fair proportion of the housing in this county was wired a long time ago and extended piecemeal since. Victorian terraces in Gloucester and Tewkesbury, Forest of Dean mining terraces at Cinderford and Lydney, and interwar semis across Longlevens and Warden Hill often have a consumer unit that is full, a loft circuit of uncertain history, or a lighting circuit that somebody has already borrowed from once.

So the survey looks at the board before it promises a supply route. What is being checked is whether there is a spare way, what protective devices are in place, whether the loft has an accessible circuit near the window position, and where an isolator could sensibly live. It is also worth keeping the rooflight supply off the lighting circuit of a loft room, because an opening unit that stops working every time a bulb takes a circuit out is an irritation that lasts for years. All of that is written into the survey notes, so the fixed price includes the actual route rather than an assumed one.