Drill correctly – It’s so easy to track down the power line

If a shelf or the latest family picture is to be hung up, the drill is used. However, before drilling begins, the wall must be specifically examined for the power lines installed behind it. If you simply drill, you risk a damaged cable, an expensive workman’s bill and a life-threatening electric shock. Discover how to avoid such a risk and how to skillfully locate your power lines in the wall.

  • Why should power lines be found?
  • Is there an installation plan for the line route?
  • How do power lines usually run?
  • How do I identify power lines in the wall?
  • What happens when you drill into a power cable?
  • How do I react correctly in the event of damage?
  • Conclusion: think first, then drill

Due to the high demand, we have updated this article and added the question “What happens if you drill into a power cable?”.

Why should power lines be found?

Quickly drill a hole in the wall: It sounds tempting, but it is not recommended. Why? The power lines running in the wall are not visible from the outside and can quickly be hit by the drill unintentionally.
If a power line is drilled into, it’s annoying at first, because you’re most likely sitting in the dark. In addition, damage to the power cable is not only associated with follow-up costs for the repair but may also pose a risk of injury for the eager driller.
Even if you only need to quickly drill a hole for a picture frame, you should make sure beforehand that there are no cables running in the wall provided for this purpose. This is the only way to avoid accidents, injuries and damage to property.
TipWhen drilling, you should not only pay attention to power lines but also to water pipes to avoid water damage.

Is there an installation plan for the line route?

Before you can start drilling, you first have to locate the lines. This naturally raises the question of whether the course is recorded in a plan. If the craftsman responsible for the electrical installation has not just drawn cable figures and has carried out the installation professionally, he has also drawn up a plan for it.
An installation plan of the line route is basically the simplest solution for locating the lines. However, these plans are often not available, even for relatively new buildings, because the relevant electrician is either unknown or not available. After all, very few electricians are happy about a spontaneous invitation to drill on a Sunday.
Note: When drilling according to the installation plan, make sure that subsequent changes to the electrical installation are also visible on this plan. 

How do power lines usually run?

In modern buildings, in particular, it can be assumed that the power lines were laid according to a fixed principle during construction. With a professional installation, the installation zones are observed and the power lines only run vertically and horizontally to the floor and ceiling.

How close to the socket drill?

The first thing to do is locate the outlet or light switch near the area to be drilled. From this point, the cable runs vertically up or down. According to the rule, the vertical power line is converted to a horizontal one about 30 cm below the ceiling or 30 cm above the floor.
Accordingly, the area can be used from a distance of 30 cm from the ceiling to 30 cm from the floor. In bathrooms, the pipes are usually not laid near the floor, but below the ceiling.
Note: This logic can only be used when drilling if there is a certainty that the electrical installation has been carried out in accordance with the regulations. In older buildings, in particular, it cannot be assumed that the cables were laid in such an orderly manner. When in doubt, it’s safer to trace the cables in the wall.

How do I identify power lines in the wall?

If there is no installation plan or you are not sure if the plan is up to date, there are other ways to locate the power line in the wall. Such devices can be the safest solution, especially in old buildings, since there is often no direct plan and the cables in the wall may not have been laid in an orderly manner. Two main types of locating devices are used: line locators and metal detectors.

How reliable are line locators?

Cable locators reveal electrical voltages. Therefore, to trace a power line, run the device over the wall until the power finder deflects. Since this procedure does not detect the line itself, but rather the voltage surrounding a line, the approximate area rather than the exact route of the cable is displayed. Therefore, do not take it too precisely and plan a sufficient distance to the determined area when drilling.
Tip: Since line locators detect electrical voltage, they only work if there is actually voltage on the line. So make sure the fuse is on. It is particularly easy to find the line when the current is actually flowing. It is, therefore, best to switch on the light or your karaoke system.

Which lines can be traced with metal detectors?

With the help of special metal detectors for house walls, it is not voltages that are detected, but metal deposits. They are therefore suitable for searching for power, gas and water lines. The devices are sensitive enough to also detect metal lines that are laid in a plastic conduit.
NoteIn modern buildings, water pipes made of pure plastic are often installed. These are not detected by metal detectors.

Can you find power lines with the app?

Finding the power line with the app sounds like a great idea. Because modern tablets and smartphones usually have magnetic field sensors that can theoretically also be used to detect power lines. However, the sensors are not always strong enough to reliably detect the cables in the wall. In addition, the result can be distorted by electromagnetic waves from devices such as televisions or PCs and is rather unreliable. Neither the search for the line nor the drilling via the app is promising solutions.

What happens when you drill into a power cable?

If you are toying with the idea of ​​just drilling into it, then you should think twice about it. If you drill into a power cable, it can have a wide variety of consequences.
If the power cable is still live when you start drilling, there is a risk of fatal injury, as you could suffer an electric shock while drilling. If you’re lucky, your fuse blows, shorts out, and maybe sparks fly.
Even in the best-case scenario, the result is a nuisance: you have a damaged power cable in the wall and need to have it repaired.

Did I drill into a power line?

Have you been busy drilling and now you suspect that you have drilled into a cable? A clear indication that you have drilled into a power line is a loud bang, flying sparks or a fuse blowing. There may also be a short circuit or you are suddenly left in the dark.
However, it is also possible that you have drilled into the protective conductor. Then nothing happens to the outside, but the most important protective measure of your power supply is damaged.
Even if you turn the backup back on and everything seems to be working normally, it’s not something to be taken lightly. Not only may the protective earth wire be affected, but it could also be that the power line insulation is damaged.
As a result, the cable is no longer so resilient and there is a risk that an apartment fire will develop at some point.

How do I react correctly in the event of damage?

Ideally, you shouldn’t have to ask yourself this question, but sometimes things don’t go well. So what if you did drill into a power line? Then caution is called for and the cable must be repaired.
In most cases, there is a direct power failure and the residual current circuit breaker, circuit breaker or fuse has blown. Never turn on the switch or fuse again. If the switch or fuse has not blown, be sure to turn it off. In any case, secure the switches against being switched on again.
If the power does not fail, the defective power cable is either currently de-energized or was only scratched. Even then, the cable cannot continue to be used normally under any circumstances. If the insulation of the cable is defective, a gradual danger develops: with the continued operation, the cable overheats, sparks fly and the cable fire is inevitable.
Note: Repairing a faulty power cord is not safe for laypersons and can be dangerous. Contact an electrician and have the damage repaired by a specialist

Conclusion: think first, then drill

Sometimes it helps to just get started and see what comes up. Definitely not when drilling in the wall. This becomes clear at the latest when it flashes briefly while drilling and you are sitting in the dark. Therefore, consider the drill site carefully before you start drilling.
Ideally, the line route can be read from the installation plan or, with a little logic, can be deduced from the usual distances to the wall and ceiling. If a plan is not available and the installation zones are not entirely reliable, it is preferable to use line locators to locate the power line rather than a drill.
If you have opted for the optimistic approach and accidentally drilled into a power line, it must be checked extensively. Even if no damage is apparent at first glance, you should definitely leave this part to the professional electrician.