What actually happens on fibre installation day?
Short version: an engineer runs a fibre cable to your home, drills one small hole to bring it inside, fits a white box called an ONT, then connects your router and tests the line. Openreach’s own guidance says to allow around four hours, so book the time off accordingly rather than hoping for a quick visit. Some straightforward jobs finish sooner, but four hours is the figure to plan around.
You’ll usually get a call the day before, and again on the morning, to confirm the engineer’s still on track. It’s worth keeping your phone nearby on fibre installation day itself, since a missed call can mean a missed slot.
If your street has just had full fibre built, or you’re moving into a new build, the process is broadly the same. The one difference is how much external work is already done, which affects how long fibre installation day actually takes.
How do you get ready before the engineer arrives?
Someone over 18 needs to be in for the whole appointment, and if you rent, get your landlord’s sign-off before you book. Openreach asks you to confirm you have the landlord’s permission for any drilling inside or outside, and you’ll be asked to sign a permission form before the engineer starts any drilling or digging. Nothing stalls fibre installation day faster than an engineer stood on the doorstep with nobody able to say yes to drilling a wall.
Think about where you want the router before they knock. Openreach’s guidance is to put it near a power socket and away from enclosed spaces like the cupboard under the stairs, since that’s what decides how far your wifi actually reaches. A router stuffed in a cupboard runs hotter too, which is its own separate headache.
Clear access to the spot where the cable will enter, usually near your existing phone line or a sensible outside wall, saves everyone time. Fifteen minutes of tidying beats an engineer working around a stack of boxes.
Fibre installation day at a glance
| Stage | What happens | Roughly how long |
|---|---|---|
| Confirmation call | Engineer confirms the appointment window | Day before / morning of |
| External work | Cable routed to the property, one small hole drilled | Varies with the route |
| Internal fit | ONT fitted, router connected and tested | Varies with the property |
| Total visit | Openreach’s own guidance for a standard install | Allow around 4 hours |
Checked September 2026, against Openreach’s own installation checklist. If ducts are blocked or the route is unusually complicated, the engineer may need a second visit rather than finishing everything in one go.
What’s the ONT box, and where does it go?
The ONT, or Optical Network Terminal, is the small white box that connects the fibre optic cable and gives your property access to the full fibre network. It needs to sit near a double power socket and close to your router, so it isn’t always in the room you’d choose.
Your router then plugs into the ONT rather than into a phone socket, which is the biggest practical change from old copper broadband. If you’re still weighing up whether full fibre is worth the switch, that’s the piece of kit that makes it possible.
What should you check once the engineer’s gone?
Run a proper speed test before they leave, not just a quick glance at a bar on your phone. Ask them to confirm the speed matches what you’re paying for, since that’s much easier to sort out on the spot than over the phone a week later.
Walk around the house with your phone or laptop and see where the signal drops. Fibre installation day fixes the connection coming into your home, but it doesn’t automatically fix a weak signal in the back bedroom or the garden office. That’s a router placement problem, not a broadband problem, and it’s worth knowing the difference before you call anyone to complain.
Keep the old router boxed up for a week or two rather than binning it straight away. If your new connection drops out in the first few days, which does happen occasionally, having the old kit to hand makes troubleshooting far less stressful.
Checklist for fibre installation day
Before the engineer knocks
- Block out around four hours, and confirm someone over 18 will be home for the full window.
- If you rent, get your landlord’s permission for drilling inside and outside before you book.
- Decide where the router will live, near a power socket, away from an enclosed cupboard.
- Clear access to the outside wall or existing phone line where the cable will come in.
- Have a way to test the connection once it’s live, like a laptop or phone, before the engineer leaves.
None of this takes long, and it’s the difference between fibre installation day running smoothly and losing an afternoon to a second visit. Roo reckons ten minutes of tidying is the cheapest insurance you’ll ever buy against a wasted morning off work.
Frequently asked questions about fibre installation day
- How long does fibre installation actually take?
- Openreach says to allow around four hours. Some jobs finish faster, but book the time off on the basis of four rather than assuming an hour, because you need to be there for the whole visit.
- Do I need to be home for the whole appointment?
- Yes. Someone over 18 needs to be present throughout fibre installation day, since the engineer needs access inside as well as outside.
- Will the engineer drill into my walls?
- Usually one small hole, to bring the fibre cable inside near your existing phone line or a sensible outside wall. Openreach engineers ask you to sign a permission form before any drilling or digging, and they repair the holes and clear up afterwards.
- What if I’m renting?
- Get your landlord’s permission before you book. Openreach requires the owner’s sign-off for drilling inside or outside, and skipping this step is the most common reason fibre installation day gets delayed.
- Can I keep my old broadband running until fibre is installed?
- Often yes, if it’s with a different provider or service, though check with your existing supplier. Once the new line is live and tested, you can cancel the old one.
- What happens if something goes wrong on the day?
- If ducts are blocked or the route turns out to be more complicated than expected, the engineer may book a second visit rather than finish everything at once. It’s frustrating, but not unusual.
- How soon should I test my speed after fibre installation day?
- Straight away, while the engineer’s still there if possible. It’s the easiest moment to flag a problem, and far simpler than raising it with support once they’ve left.
Sources
- Openreach, Full fibre broadband installation checklist. The four hour guidance, the over-18 requirement, landlord permission and the drilling permission form, and what the ONT is and where it goes.
Checked 23 September 2026. It’s a genuinely quick read, and worth ten minutes the evening before rather than a panicked scroll while the van’s already outside.
