Chasing for Electrical Installations

Manual Chasing

Manual chasing is a traditional method using basic tools such as a hammer, chisel, or hand gouge. It is a more time-consuming approach but still has its place – especially where electrical tools cannot access or in historic buildings with delicate structures.

Advantages and Disadvantages

The advantage of manual work is high precision in details and minimal risk of excessive damage to masonry, which is ideal, for example, for minor repairs or for running chases for sockets and switches in hard-to-reach areas.

The disadvantages are longer completion times, higher physical exertion, and the possibility of uneven cuts, which can affect subsequent cable laying.

Use in Smaller and Less Accessible Areas

Manual chasing is often applied in small flats, bathrooms, or older concrete block buildings where it is necessary to preserve as much of the original structure as possible. It is also used in electrical renovation projects where the goal is to intervene in the existing structure as minimally as possible. This method is also suitable for repairing individual branches of electrical wiring in a flat, without the need for extensive structural intervention.

Machine Chasing

For larger scopes of work, machine chasing is far more efficient. This method utilises professional wall chasing machines equipped with powerful blades – often diamond-tipped – capable of cutting through hard materials like concrete, brick, or aerated concrete.

Speed and Efficiency

The greatest advantages are speed and consistency. Machine chasing shortens installation time, reduces labour costs, and allows for complex projects to be completed quickly. When combined with an industrial vacuum, dust is minimised, which is a significant plus for internal work.

Use of Diamond Blades and Wall Chasers

Modern cable chasers are designed to cut with precise chase depth for cables – most commonly 2–4 cm – and width according to installation needs. The use of diamond blades ensures a clean cut without excessive damage to the masonry and with high directional accuracy.

Chase Depth and Width for Various Electrical Installation Types

For standard electrical work in domestic properties or flats, the chase depth should be at least 2 cm for installing standard electrical cables. For larger main supply cables (e.g., to a cooker or consumer unit), a greater depth is recommended – up to 4 cm, or running cables in conduits.

When choosing the correct depth and width of chases, the type of wall material must also be considered – chasing into concrete panels requires different tools and approaches than chasing into brickwork or aerated concrete.

Choosing the correct type of electrical chases is crucial for the functionality and safety of the entire installation. Different wiring systems require different dimensions, orientation, and placement of chases. If the chasing is done poorly or inappropriately, it can lead to difficult cable laying, damage to wall integrity, or future malfunctions.

Chases for Sockets and Switches

The most common type are chases for sockets and switches, which are installed at heights of 30 – 120 cm from the floor, depending on the purpose and interior design. These are short horizontal or vertical chases that run from the floor or ceiling to installation boxes. These boxes are recessed into the wall and serve as points for electrical appliances.

During electrical renovation in older concrete block flats, it is often necessary to create these chases anew, especially if the layout of sockets and switches is being changed to meet current requirements.

Vertical and Horizontal Chases

Vertical chases run vertically from the ceiling to sockets, switches, or junction boxes. This is the preferred direction due to easier orientation for future maintenance and greater safety. Horizontal chases run parallel to the floor, usually at installation heights where cables branch off into multiple rooms or elements.

It is important to adhere to directional rules, which stipulate that cables must be run exclusively horizontally or vertically – never diagonally. This simplifies cable location in case of repair and protects against accidental damage.

Chases for Main Supplies and Consumer Units

For the main power supply of a flat or house, wider and deeper chases for cables with larger cross-sections are required. These run from the electricity meter or main consumer unit towards sub-consumer units, socket circuits, and lighting circuits. They are usually located in utility rooms, shafts, or along structural walls.

Such chases must meet stringent standards for cable chase depth, ensure heat dissipation, and be resistant to mechanical damage. In many cases, machine chasing is used for these purposes, allowing for precise adherence to the required parameters.

Specifics of Electrical Installation in Concrete Block Buildings

Electrical installation in concrete block buildings has its specifics – the panels are made of concrete or reinforced concrete, which significantly complicates chasing walls. Older installations are often surface-mounted or run in pre-prepared channels within the panels. When replacing them, it is often necessary to chase into concrete panels, which requires professional equipment such as diamond saws, grinders, or core drills.

Due to the strength of the material and structural limitations, it is essential to consult a specialist for this work. In many cases, running new wiring in plasterboard dry-lining is recommended, which eliminates the need for chasing into structural panels.

Properly created electrical chases are not just a matter of aesthetics and functionality, but also safety. British Standards (BS) set clear rules regarding the width, depth, and placement of chases in various types of building structures. Failure to comply with these standards can lead to problems during final inspection, increased fire risk, or even damage to the structural elements of the building.

Maximum Permitted Depths and Widths

According to BS 7671 (IET Wiring Regulations) and recommendations from electrical system manufacturers, the chase depth for cables should not exceed:

• 20 mm for simple lighting circuits,
• 30–40 mm for socket circuits or cables in conduits,
• 50 mm and more only in exceptional cases – after structural assessment.

The width of the chase depends on the number of cables and their cross-section, but in most domestic installations, it ranges from 20 to 40 mm. For chasing for cables with higher currents (e.g., power supply for kitchen appliances, boiler, or air conditioning), the thermal output of the conductors must also be considered to prevent overheating.

Distances from Ceilings, Floors, and Corners

Standards also specify minimum clearances that must be observed when chasing walls:

• a minimum of 10 cm from the ceiling,
• 20–30 cm above the floor for horizontal chases,
• 15 cm from room corners,
• and a minimum of 5 cm from the edges of openings (windows, doors).

These rules are not arbitrary – they serve to allow cables to be located years later without the need for a detector, which is invaluable during renovations and installation of new equipment.

Recommendations According to BS and Safety Principles

In addition to dimensions, it is crucial to adhere to the directional routing of cables – exclusively vertically or horizontally. Diagonal routing is generally impermissible and can lead to damage to insulation layers during subsequent interventions in the masonry.

Another standard to consider for electrical work is BS 7671, which defines the conditions for installing electrical wiring in various environments. For example, in bathrooms, stricter rules apply to cable routing due to increased humidity and the risk of electric shock.

All these standards and principles must be observed by tradespeople carrying out chasing work for electrics, especially when working in residential areas, educational institutions, or public buildings.

The cost of chasing for electrical installations can vary significantly depending on several factors – from the type of technology used to the complexity of the room and the hardness of the material.

The electrical work price list for 2026 helps with orientation on costs, reflecting current prices for materials and labour.

A comprehensive building work price list can also assist, which includes indicative prices based on the type of execution and complexity of a specific project.

Chasing is usually not done in isolation but forms part of a project such as electrical installation + full fit-out for a 1-bedroom, 2-bedroom, 3-bedroom, 4-bedroom, or 5-bedroom flat. The larger the flat and the more sockets, switches, and circuits need to be prepared, the greater the length and complexity of the chases, which directly translates into labour costs and completion time.

Price Based on Chasing Technology

One of the main differences is the method of execution:

Although chasing walls for electrical installations may seem like a straightforward job at first glance, practice shows otherwise. Incorrect procedures can cause serious problems – from compromising the structural integrity of the building to the risk of electric shock. If you plan to chase yourself or hire a tradesperson, you should be aware of these common mistakes to avoid.

Damaging Structural Elements

One of the most dangerous mistakes is chasing walls in areas containing structural elements – for example, transverse bracing, load-bearing columns, or pre-stressed concrete panels. Especially when chasing into concrete panels, there is a risk that without professional assessment, the structural integrity of the entire construction will be compromised. This can result in wall cracks, settlement of the building, or reduced load-bearing capacity.

Therefore, it is recommended to consult a structural engineer or building surveyor before any extensive chasing for cables in concrete block buildings.

Ignoring Directional Rules

Standards and common sense clearly state – electrical chases must be run vertically or horizontally. However, some "creative tradesmen" still run cables diagonally, which is a major error. Not only does it complicate future maintenance, but it also increases the risk of damaging conductors during any subsequent building work – for example, when drilling for shelves or fixtures.

Proper chasing work for electrics always respects the rule of straight-line routing. Furthermore, when running a cable from a socket to the ceiling, for example, the chase must be run vertically upwards, never diagonally.

Incorrect Depth or Unnecessary Chasing

Another common mistake is an incorrectly estimated chase depth for cables. Chases that are too shallow can lead to cable damage during plastering, while excessively deep ones unnecessarily weaken the wall. In extreme cases, cables may "float" in the plaster, not being securely fixed, and can get damaged over time.

Unnecessary chasing is, in turn, a result of poor planning – if someone changes the cable route during installation, it leads to duplicate cuts and unnecessary damage to the masonry. This is why thorough preparation for electrical installation and marking the route beforehand is crucial.

Although chasing walls may seem like a job a skilled DIYer can handle, it actually requires experience, technical skills, and especially knowledge of electrical installation standards. Therefore, it's important to know when you can tackle it yourself – and when it's better to call in a professional.

When to Call in a Professional?

For extensive electrical work, such as a complete rewire of a flat or electrical renovation in a concrete block building, we definitely recommend engaging a qualified firm. Professionals have the necessary equipment (diamond blades, wall chasers, dust extraction), are familiar with the building work price list, and can estimate the correct chase depth for cables according to the type of wiring.

Furthermore, a professional firm will guarantee you:

• adherence to all technical standards,
• minimising interventions in structural elements,
• safe cable routing according to BS,
• fast and precise execution without unnecessary waste.

How to Prepare the Area Before Chasing?

Proper preparation for electrical installation saves time and money. Here are some practical tips:

• Mark out the locations for sockets, switches, light fittings, and cable routes.
• Ensure there are no water, gas, or other services in the walls.
• Remove furniture, cover floors, and important items to protect them from dust.
• Ensure access to electrical connections and the consumer unit.

What to Look Out For When Choosing a Firm?

If you decide to approach a tradesperson or firm, pay attention to several important points:

• Check references – look at ratings, reviews, or ask for examples of completed work.
• Insist on a price upfront – a reputable contractor will provide you with an accurate building work price list, including all items.
• Ask about the technology – professional firms use modern machine tools with dust extraction.
• Agree on deadlines – not just the start, but also the completion of work.
• Do not underestimate documentation – every electrical installation should have documentation including cable locations and safety protocols.

Advice and Tips Before Chasing

Before starting chasing work, always prepare a precise electrical installation plan. Mark out cable routes, locations of sockets, switches, and consumer units before any work begins on the masonry. This will save time, reduce the number of unnecessary chases, and minimise damage to walls.

In concrete block flats or older buildings, verify that there are no existing water, gas, or old electrical wiring in the walls. Using a cable detector can prevent serious problems and dangerous situations.

To ensure that chasing work is carried out safely, cleanly, and in compliance with standards, get a quote in advance. Comparing prices and technologies will help you choose the right approach and avoid unnecessary compromises on quality.

Before embarking on chasing for electrical installations, it's wise to clarify a few fundamental facts. Many chasing mistakes are avoidable and simply stem from insufficient planning or lack of knowledge.

The Importance of Well-Prepared Chases

Precisely created electrical chases are the foundation of a functional and safe electrical system. Poor execution risks cable overheating, mechanical damage, or failure to comply with safety standards. Moreover, if chases are run unprofessionally, it can prolong installation time, increase material consumption, and raise the final cost.

Saving Time and Money Through Proper Planning

Well-planned wall chasing saves time, money, and stress. Mark out all electrical installation points in advance, check routes, determine the chase depth for cables, and prepare at least a basic building work price list.

Don't forget to consider the final phase of electrical installation – after wiring and surface finishes are complete, fitting of light fixtures follows. For recessed solutions, precise hole cutting is performed in the ceiling. Accurate measurement prevents cable damage and ensures a clean flush fit of fixtures with the ceiling without additional repairs.

Reliable and Professional Solution Through Numiq

If you want to be sure that the work proceeds smoothly, safely, and at a fair price, use Numiq for comparison and calculation – a digital tool for estimating building work costs. You will get an immediate overview of:

• how much manual or machine chasing will cost you,
• what impact the type of masonry or wall height has,
• how much additional services cost,
• and what the current electrical work price list is in your region.

Don't Know Where to Start? Test Your Project in the Numiq Calculator

As the final price of electrical installation depends on many factors, you will get the most accurate picture by comparing specific project parameters. The digital Numiq calculator allows you to quickly find the current electrical work price list, compare solution variants, and get a realistic cost estimate before work begins.

Enter the parameters of your electrical installation, select the type of masonry, and have the price calculated automatically. The system will also recommend the most efficient method of chasing for cables and assist with choosing a reliable supplier.

Sources:

MurarskePrace.net – Electrical Installation Price List

Porovnej24.cz – Electrician and Plumber Hourly Rate 2022

Stavebnictvo.sk – Electrical Installation Standards and Implementation

ElektroAntoš – Blog on Electrical Installation in Flats and Houses

Ceníky Řemesel – Electricians: Chasing Walls / Grooves

LevEnergo.cz – SERVICES PRICE LIST – Electrical Installation Work