The drill bit was almost through. A brief tremor in the hand, then: bang. Fuse blown. Everything dark. Or – and this is the more dangerous scenario – nothing happened at all. No bang, no spark, everything seems normal. This is precisely the moment when many people make their biggest mistake.
Two scenarios – one correct course of action
Anyone who has drilled into a cable in the wall usually experiences one of two scenarios:
Scenario 1 – The Bang: The fuse blows, there’s a smell of burning, perhaps a brief flash of light. It’s immediately clear that something has happened.
Scenario 2 – The Silence: Nothing happens. The drill continues to run, the light is on, everything seems fine. The cable may have been de-energized, or perhaps only the insulation was scratched without hitting a live wire.
Both scenarios require the same response: stop immediately, turn off the power, and call a professional. The difference is that the second scenario doesn’t feel urgent – and that’s precisely why it’s often the more dangerous situation.
Immediate action – This order matters
Don’t panic, but don’t hesitate for a second either. If you ‘ve hit a cable while drilling , proceed exactly as follows:
Step 1: Immediately pull out the drill. Do not continue drilling, do not shake – remove the drill and put it away.
Step 2: Don’t touch anything. The damaged cable, the surrounding wall, the drill itself – don’t touch anything, even if the fuse has blown. Residual voltage may still be present.
Step 3: Go to the fuse box. Switch off the affected circuit – if in doubt, switch off several or all of them. If you don’t know which circuit is affected, switch them all off.
Step 4: Secure against reactivation. A note on the fuse box, a piece of tape over the switch – ensure that no one in the household switches the fuse back on before an electrician has been there.
Step 5: Call an electrician . Not tomorrow. Not the day after. Now. Drilling into a cable is not a cosmetic problem – it’s a safety hazard that continues to have an effect inside the wall, even if you can no longer see it.
Why “looks okay” is no all-clear
Herein lies the real risk: A cable whose insulation is only slightly damaged, without a conductor being completely severed, initially goes unnoticed in everyday use. The current continues to flow, everything works.
But something happens at the damaged area: Over time, the damaged insulation allows moisture to penetrate. Contact surfaces oxidize. Under stress, this creates increased resistance, generating heat – invisible behind the plaster, for days or weeks. Our article on the warning signs of a cable fire describes the potential consequences – a risk that is often underestimated because it develops gradually.
Even in a house in Spandau that was renovated just three years ago, a drilled hole can become a silent source of danger.
Repairing drilled cables – what is allowed, what is not?
First and foremost: Only a licensed electrician is permitted to repair a cable that has been drilled into. This is not just a recommendation – it’s the law. Anyone attempting to repair it themselves risks not only their own safety but also their insurance coverage.
But what exactly happens during the repair?
Method 1: Flush-mounted box with terminals
The most common and cleanest solution. The damaged area is exposed, the cable is cut on both sides of the break, and the connection is made in a newly installed flush-mounted box using approved connectors (for example, WAGO 221). The box remains accessible – this is a requirement according to DIN VDE 0100.
Method 2: Potting sleeve
For damaged areas that are difficult to access or where a flush-mounted box cannot be sensibly placed, a potting compound or shrink sleeve is used. This is slipped over the damaged area and permanently sealed. This method allows the sleeve to remain embedded in the plaster.
Method 3: Replace the entire cable
If several areas have been damaged – for example, during a kitchen renovation with many drill holes in Marzahn or Tempelhof – replacing the entire cable segment is the safest and often cheapest solution.
Which is absolutely forbidden
Insulating tape, terminal blocks in the plaster, twisting the wires, silicone as a “seal” – all these are not repair methods, but bodges that only hide the problem and increase the risk.
How to repair a drilled-through cable – cost overview
| Performance |
Costs (approx.) |
| Emergency response + diagnosis |
€80 – €200 |
| Repair with flush-mounted socket |
€150 – €350 |
| Repair using a potting sleeve |
€120 – €280 |
| Complete cable replacement (per meter) |
€30–80 |
| Open, repair, and plaster a wall |
€200 – €500 |
The actual costs depend on accessibility, the depth of the pipes, and the effort required for chiseling and plastering work. In older buildings with hard masonry – as is often the case in Prenzlauer Berg or Charlottenburg – the effort can be higher.
Cable locator for wall mounting – Could this have been prevented?
Mostly, yes. A wall cable detector – also called a pipe and cable locator – identifies the location of cables, pipes, and metal parts in the wall before drilling. Briefly running the device along the wall before each drill hole significantly minimizes the risk.
However, no device is infallible. Cable detectors work in two dimensions – they show where a cable runs, but not always at what depth. Anyone drilling particularly deep, or working in an old building in Berlin’s Friedrichshain district where cables are sometimes laid diagonally and at unusual depths, can still hit a cable despite using a detector.
A basic model is available for 20 to 50 euros and belongs in every household that occasionally uses a drill. For frequent DIYers, a higher-quality model with radar technology is worthwhile, starting at around 150 euros.
Special features of Berlin apartments
Berlin is a city of old buildings – and old buildings have old wiring. In Gründerzeit-era buildings in Kreuzberg , Neukölln , or Wedding, cables sometimes run exactly where no sensible electrician would lay them today: diagonally, at unusual heights, or directly behind thin plaster.
Anyone drilling in such a building should be especially careful – and if in doubt, it’s best to ask an electrician before starting to drill.
What should you do if you accidentally drill into a cable in a rented apartment?
Here’s another dimension to consider. In a rented apartment in Lichtenberg or Reinickendorf, a drilled-through cable doesn’t just affect the tenant – it also affects the landlord, the building, and potentially other parties.
Immediate measures: Switch off the electricity, inform the landlord or property management company, hire an electrician.
Insurance: In many cases, personal liability insurance covers the costs of damage caused by drilling – provided that the drilling was done without gross negligence or gross violation of regulations (for example, without checking for pipes or cables). Take photos of the situation before attempting any repairs.
Important: Do not attempt to repair it yourself to save money. This will only make the situation worse.
If you are unsure what to do next in such a situation, our article on hiring an emergency electrical service explains the process step by step.
Elektriker-24std.de – Emergency call-out for damaged cable in Berlin
A damaged cable is an emergency – and that’s exactly what we’re here for. Our 24-hour emergency service is available throughout Berlin, from Pankow to Zehlendorf , from Mitte to Köpenick . We come, inspect, and repair – professionally, with documentation and no hidden costs.
Call now: 0176 – 160 519 01
Conclusion: One moment of inattention, one clear reaction
If you’ve drilled into a cable, what should you do ? The answer is always the same: turn off the power, don’t touch anything, call a professional. Whether there’s a bang or silence, whether it’s a rented or owned apartment, whether it’s newly renovated or an old building in Tempelhof – the procedure doesn’t change. What does change is the risk if you wait too long.
FAQ – Cable damaged by drilling
Yes, absolutely. Even slightly damaged cable insulation without sparks or a blown fuse is a safety hazard that must be professionally repaired.
No. Repairs to fixed electrical wiring may only be carried out by licensed electrical contractors. DIY repairs with insulating tape or terminal blocks are prohibited and dangerous.
In many cases, yes – especially if there was no gross negligence. Important: Take photos before any repairs are made and report the damage to your insurance company.
Use a cable locator before drilling. In Germany, cables usually run vertically or horizontally from switches and sockets according to standards – check these areas particularly carefully.
We are available 24 hours a day – even at night and on weekends. In emergencies, we coordinate the response as quickly as possible. Call us: 0176 – 160 519 01. Do I need to call an electrician immediately, even if nothing has happened?
Am I allowed to repair a drilled-through cable myself?
Will my liability insurance cover the damage?
How can I prevent drilling into cables in the future?
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