Electrical wiring under plaster: installation rules, chasing, finding hidden cables

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Plastering over electrical wiring can greatly enhance your home’s safety and appearance. Embedding wires under plaster provides a seamless, clean appearance, as opposed to having them hidden by surface-mounted channels or running along the walls. This method lowers the risk of fire and provides improved protection against physical damage in addition to keeping cables hidden.

But in order to guarantee that the electrical wiring is secure and operational for many years to come, correct installation is necessary. When installing electrical wiring beneath plaster, there are particular guidelines to adhere to. These include knowing how to properly chase walls, secure cables, and make sure everything is code compliant. By mastering these techniques, you can steer clear of potentially dangerous situations and expensive errors.

If hidden cables are not found correctly, it can be difficult to find them for maintenance or renovation projects. For those doing renovations or construction, finding these cables without breaking your walls or interfering with other systems is a critical skill. This tutorial will take you step-by-step through the fundamentals of safely installing and locating electrical wiring beneath plaster, providing do-it-yourselfers and pros with useful advice and methods.

What first, plaster or wires?

When should electrical wiring be completed—prior to or following plastering? There is a disagreement here between a plasterer and an electrician. Everyone will find it more convenient if they complete their assigned tasks first and without intervention. However, in the event that you, or a single master, are performing the repairs, the steps involved will be as follows:

1. Walls are cleaned of old finishes. They draw lines along which the wires will pass, the places where the socket boxes and junction boxes will be installed.
2. Under thick wires and corrugation, grooves (grooves) are laid along the entire length to exit points: switches, sockets. The use of corrugated channels is mandatory when the walls are made of combustible materials. They are also used to make it possible to pull out and replace wires. Laying cables in plaster is allowed without corrugation.
3. Thin wires can be laid directly over the surface without gating, if a layer of plaster mortar hides them.
4. Next, the electrical wiring is laid and fixed to the wall.
5. The walls are plastered with or without beacons. The ends of the wires protruding from the channels can be wound up and covered with film.
6. After the walls have dried, use a hammer drill with a crown to drill out spaces for sockets, junction boxes and switches. This is done after plastering, because otherwise it is not clear to what depth they will be installed.
7. Then the final finishing is done – wallpaper or decorative plaster. After this, sockets and switches are inserted.

There is, however, one argument in favor of finishing all electrical wiring after the walls are plastered. If the walls are to have grooves installed, it is much simpler to do this on a layer of plaster, say on the second or third day, before it has completely dried. Brick or concrete grout requires more time and dust to remove.

Rules for installing electrical wiring

Electrical wiring must adhere to widely recognized building codes and specifications in order to be safe and long-lasting. Therefore, you need to familiarize yourself with the electrical installation rules (PUE) before drilling holes in the wall for cables. The following factors determine where the wiring will be installed:

• 15-20 cm above the baseboards;
• 20-30 cm below the ceiling and beams;
• 10 cm from the corners;
• in the area of ​​​​heating pipes, gas pipes with an indent of 50 cm.

Cables for televisions fall under this as well.

Purchasing wires in coils is preferable. There won’t be a need to install spliced and insulated connections beneath the plaster in this instance because the cables will be solid.

Hidden electrical wires can be found in floors, walls, or corrugated pipes. There can be no corrugation when laying on a non-combustible surface, such as plaster.

Aluminum wires can only be used with a cross-section of 16 mm2 or more, according to the PUE. reduced cross-section, limited to copper. This is because copper has a lower electrical resistance than aluminum. It becomes heated and could melt under high loads.

The following kinds of wires are utilized, depending on the installation circumstances:

• VVGng: fire-resistant, non-flammable, for laying under plaster;
• VVGng-LS: mainly for drywall, for protection against mechanical influences it is laid in PVC boxes; its analogue can be a gray cable NYng-LS with a rubber layer, more expensive, easy to install, not very convenient for grooves, since it has not a flat, but a round cross-section;
• PVC: multi-core, white, can only be used as an extension cord or when connecting electrical appliances directly to the socket.

A 3-core cable is used in new electrical wiring, whereas a 2-core cable is used in older wiring. Four cores are needed for chandeliers with a two-button switch.

Chasing walls for hidden wiring

Before beginning work, a diagram must be created showing the locations of all switches, power outlets, distribution boxes, and sockets for them. It also must show where the lines that will be used for chasing will be. Such a diagram needs to be preserved on paper or in electronic format to prevent damage to the wiring during renovations, switch and socket relocations, hanging structure installations (shelves, sconces, hangers, etc.).

Crucial! Please be aware that it is against the rules to chase load-bearing walls and drill holes through them. Thus, all wiring ought to go through a plaster layer only.

The locations of panels, sockets, switches, and lamps are marked first, followed by the wire route. Every line needs to be precisely vertical and horizontal. They are marked using a plumb line, laser, or ordinary building level and chalk, pencil, or marker.

Only attics and staircases are permitted to have inclined lines as long as they run parallel to the inclined surface. In this instance, it will take less time to look for damage on straight lines, and there will be less chance of unintentional damage to the cable, such as when hammering nails for shelves or pictures.

Since a wall chaser is a relatively costly tool, grinders and hammer drills are typically used to create wiring grooves. The excess plaster is first chipped off between the two grooves using a hammer drill after they have been prepared with a grinder and a diamond wheel. The dimensions of the wiring dictate the size of the groove; typically, a depth of 20 to 25 mm is adequate.

It is not required to use junction boxes in the normal wiring of private homes and apartments. They are put in place to make it easier to divide lines into various groups. Distribution boxes are set in place using gypsum mortar with a slight overhang equal to the thickness of the upcoming plaster layer.

To fix the wires in socket boxes, recesses are made and partially filled with a gypsum mixture. After tucking in their ends, the extra is chopped off, leaving about 10-15 cm.

It is more practical to install socket boxes in blocks right away. They are also easier to use and have a more attractive appearance. Latches, also known as cable channels, are used in their installation. After drilling a row of holes spaced 1-2 mm apart, the partitions between the holes are taken out. Installing socket box covers comes last, right after painting or adhering wallpaper. Moisture-proof outlets with grounding are used in highly humid rooms.

How to fix a cable in a groove

All cables need to be firmly fastened before plastering. This can be accomplished using dowel clamps, for which hammer drill holes are pre-drilled in the grooves. The dowels should slide in freely, but because their clamps are wedged, it is harder to take them out again.

As per SNiP 3.05.06-85, the minimum distance between the attachment points of wire bundles is 0.5 m, while single cables have to be at least 0.9 m apart. Up to 1.2 meters when covered with dry plaster. They are further fixed on both sides of the bends at the route’s turns and end points.

Ordinary putty can also be used to secure the wire in the groove. Using pieces of corrugated pipe inserted across the channel as spacers, it is temporarily fixed to keep it from sagging and falling out while the mixture hardens. View the following video for additional details on this technique:

There are crucial guidelines for correct installation when it comes to electrical wiring hidden beneath plaster in order to guarantee your home’s functionality and safety. This includes knowing how to locate hidden cables without causing damage to your walls and comprehending the process of chasing, which involves making channels in walls for wires. By using the appropriate methods to hide and access wiring, you can prevent expensive repairs and make sure your house complies with safety regulations. This post will walk you through the essential procedures and best practices for handling electrical wiring hidden beneath plaster, from installation guidelines to effective cable location.

How to cover grooves

In order to completely conceal the electrical wiring, the grooves are sealed with a solution after the cable has been inserted. Both slab and brick buildings can use this option. This method is not recommended for wooden houses composed of beams and logs because it can catch fire. It is preferable to use the same plastering solution to coat the grooves. Take cement plaster in a new building that hasn’t been finished. It will firmly anchor the cables in brick, aerated concrete, or concrete.

Now, let’s examine the order in which I seal the grooves following the wiring installation:

• The channel is pre-dusted with a vacuum cleaner or a wide brush. Large debris should be pre-removed with a brush.
• Before laying the cable, they must be primed with a wide brush, otherwise, due to poor adhesion of the solution, cracking and falling out of the solution is possible.
• To prevent the wall from absorbing moisture from the solution, it is moistened before puttying.
• Gypsum or cement-sand plaster is thrown along the entire length of the channel. Alabaster should not be used for these purposes – it sets too quickly, forming bumps on the wall. The solution should be thick, this is not a finishing, smoothness is not really needed here. Try to fill all the voids when hiding the wire.
• Use a spatula along the wiring, removing excess mixture.

As requested, here is a succinct and understandable conclusion for your article written in plain English:

Careful planning, exact execution, and adherence to safety regulations are necessary for the successful installation of electrical wiring beneath plaster. A successful and safe installation can be ensured by knowing the fundamentals of electrical work, whether you’re an experienced professional or a do-it-yourself enthusiast.

Although discovering hidden cables and chasing walls can be challenging, with the correct equipment and understanding, the process becomes much more doable. Recall that employing a cable detector can safeguard the integrity of your electrical system and stop needless wall damage.

In the end, it’s critical to make sure that every installation complies with local electrical codes and regulations. It not only gives you peace of mind but also guarantees the safety of your house. It’s always best to consult with a professional electrician if you have any questions about any aspect of the process.

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