A company’s electrical installation is something nobody thinks about every day—until an inspection, an insurance claim, or a new tenant prompts someone to ask when it was last inspected. Yet there is no single answer to “how often” that applies to an entire building.
The interval is determined neither by the building approval date nor by the inspection technician’s intuition, but by the environment in which the wiring operates and the type of premises. A dry office, a workshop with presses, and outdoor wiring on the façade of an industrial building are all assessed differently—even though they may all be under one roof.
What is mandatory: příloha č. 4 NV 190/2022 Sb.
The maximum permitted intervals for periodic inspections of designated electrical equipment and lightning protection systems (LPS) are set out in příloha č. 4 nařízení vlády č. 190/2022 Sb., as effective from 1 July 2024.
| Premises or area | Maximum interval |
|---|---|
| Office buildings | 5 years |
| Manufacturing, education (schools and nursery schools), accommodation (hotels, hostels and campsites), and medical purposes | 3 years |
| Premises where more than 200 people may be present according to the fire safety design | 2 years |
| Temporary construction-site installations | 0.5 years |
| Mobile and transportable equipment | 1 year |
| Areas with a risk of fire or explosion | 3 years |
| Wet areas and areas with a permanent presence of corrosive or contaminating substances | 1 year |
| LPS protecting critical systems | 2 years |
| LPS protecting other premises | 4 years |
The annex adds four rules to the table:
- If equipment falls under more than one interval, the shortest one applies.
- The inspection must be performed in the year in which the interval expires; this does not apply to intervals of up to one year.
- Where a preventive maintenance plan with regular checks and maintenance is in place, intervals of up to twice the standard length may be applied.
- A visual inspection of the lightning protection system must be carried out at least once a year.
If the manufacturer’s accompanying documentation specifies a shorter interval, it takes precedence over the interval in the table. Equipment for which the annex specifies no interval must be inspected in accordance with other occupational health and safety legislation.
Why electrical inspection intervals matter
A periodic electrical installation inspection is more than a formal “piece of paper for the inspector.” It is one of the few ways to identify hidden defects before they lead to fire, electric shock, or an unplanned operational shutdown. It is also an operator’s legal obligation.
The legal framework is broader than the technical standard. Under § 101 and § 102 zákoníku práce, employers must ensure occupational health and safety and prevent risks; § 4 zákona č. 309/2006 Sb., ve znění pozdějších předpisů, also requires technical equipment to be regularly maintained, checked, and inspected. Fixed electrical installations are generally designated electrical equipment under zákona č. 250/2021 Sb. and nařízení vlády č. 190/2022 Sb., which govern requirements for their safe operation.
If you are unsure whether your electrical installation inspections meet the current requirements, we can help you clarify the situation.
Where the intervals come from: standards, not intuition
The frequency of periodic inspections is not chosen according to a technician’s mood or an impression that “everything looks fine here.” The basic maximum intervals are set by příloha č. 4 nařízení vlády č. 190/2022 Sb.; technical standards provide a more detailed breakdown by environment, with ČSN 33 1500 and the ČSN 33 2000-6 series being essential for periodic inspections. ČSN 33 1500 is not generally legally binding in itself, but it represents a recognised procedure used when assessing compliance with legal obligations.
Since 1 January 2025, ČSN 33 2130 ed. 4, which governs requirements for internal electrical wiring, has also been in force. Compliance with this standard is therefore checked during an inspection.
Nor can just anyone perform the inspection. Inspection work must be carried out by a certified inspection technician holding a valid certificate under nařízení vlády č. 194/2022 Sb. Compliance is supervised by the oblastní inspektorát práce (regional labour inspectorate) under zákona č. 251/2005 Sb., which may impose fines for identified shortcomings.
Overview of periodic inspection intervals by environment
For designated electrical equipment, the mandatory maximum intervals are stated in příloha č. 4 NV 190/2022 Sb.; the tables in ČSN 33 1500 provide the technical basis for a more detailed classification by environment.
The standard applies two criteria simultaneously—the environment or external influences and the type of premises—and the stricter of the two applies. The following overview should therefore be treated as an indicative guide, not as a binding table for your particular switchboard.
| Environment or type of premises | Indicative inspection interval |
|---|---|
| Masonry office and residential buildings; basic and normal environments (dry, clean and heated) | 5 years |
| Apartment buildings—common areas | 5 years (unless otherwise specified) |
| Shops, retail premises and public spaces | 4–5 years |
| Outdoor wiring and covered outdoor areas | 4 years |
| Schools, nursery schools, hotels and other accommodation facilities | 3 years |
| Hot, humid or dusty environments and environments with increased corrosivity | 3 years |
| Production halls and workshops, depending on the environment | 2–3 years |
| Areas intended for gatherings of more than 250 people, such as halls, venues and department stores | 2 years |
| Environments exposed to vibration and passive environments with a risk of fire or explosion | 2 years |
| Timber buildings and structures made from combustible construction materials | 2 years |
| Dusty areas with non-conductive dust, such as woodworking facilities and textile mills | 2 years |
| Healthcare premises, including surgeries and hospitals | 1–3 years depending on the zone |
| Wet environments and environments with extreme corrosivity | 1 year |
| Mobile and transportable equipment | 1 year |
| Temporary construction-site installations | 0.5 years (6 months) |
| Photovoltaic power systems, including both AC and DC sections | According to ČSN 33 2000 and EN standards, usually 2–4 years |
The interval runs from the last inspection, not from the building approval or purchase date. An assessment of the condition and risks may justify shortening it—the standard sets an upper limit that generally cannot be extended. Lightning protection systems have their own intervals under ČSN EN 62305: a full inspection is required every two years for protection classes LPL I and II and every four years for LPL III and IV.
Why “five years for the entire building” is not enough
The most common mistake made by owners of smaller businesses is to take the five-year interval for an office and apply it to the entire property. But what applies to a dry office does not apply to the workshop at the back or a switchboard on the outside wall of an industrial building. The inspection technician assesses the premises section by section, and each section may fall into a different category.
A single site can therefore have several different deadlines running alongside one another:
- the office section in a dry, heated environment with a five-year interval,
- a dusty warehouse mezzanine where handling equipment is used, with a shorter interval,
- outdoor wiring supplying car park lighting or an air-conditioning unit, with the interval applicable to outdoor environments.
All deadlines are recorded in the inspection reports and must be monitored. It is therefore worth maintaining an inspection schedule—a list of circuits showing the dates of their most recent and next inspections. The article Electrical installation inspections in office buildings explains how an office building itself is assessed and what the technician examines.
What the technician actually assesses when determining the interval
The inspection technician assesses more than the condition of the switchboard. The primary consideration is the environment in which the equipment operates, as this determines its classification and therefore the inspection interval. In particular, the technician examines:
- Humidity and temperature. In a basement or unheated industrial building with visible condensation, the insulation resistance of conductors decreases and protective-conductor connections corrode. Such environments are subject to shorter intervals.
- Dust. Accumulated dust impairs cooling and reduces clearance distances. In facilities with combustible dust, it may ignite from an overheated connection. Warehouses and production facilities therefore tend to have shorter intervals than offices.
- Shock and vibration. In machine rooms and near presses or compressors, prolonged vibration loosens screw terminals in switchboards. This increases contact resistance, causing the connection to heat up and, in extreme cases, spark.
- Mechanical stress. A cable installed at a level where forklifts pass every day is at greater risk than wiring above a suspended office ceiling. Its insulation may be abraded and the protective conductor may be severed.
- Age and installation material. The condition and workmanship of aluminium wiring dating from the 1960s to the 1980s may justify an earlier inspection or repair, although the conductor material alone does not determine a shorter interval. Under terminal pressure, aluminium gradually “creeps” or deforms, loosening the connection. Contact resistance then rises and the joint heats up—a typical cause of defects in older prefabricated residential and office buildings.
Based on the combination of these factors, the technician sets an interval within the limits of the standard. A good technician will explain the reasoning. If you need to align deadlines to plan shutdowns, the usual solution is to shorten the longer interval, not extend the shorter one.
When the interval begins: initial inspections and refurbishment
The periodic interval does not run from the building approval date, but from an inspection. For a new or refurbished installation, the starting point is the initial inspection carried out before the equipment is put into service. The first periodic inspection interval runs from that date. If the initial inspection took place in January 2026 and the premises are subject to a five-year interval, the next deadline will be January 2031. The article Initial electrical installation inspection discusses this in more detail.
Older premises that are “somehow being used” without the necessary documentation often lack an initial inspection report. In that case, an inspection should be commissioned to document the current condition and establish the starting point for the periodic interval. A common misconception is: “The electrician inspected it when they wired it.” Installation and inspection are two different roles, however. The electrician connects the equipment and verifies its function, while an inspection technician certified under nařízení vlády č. 194/2022 Sb. takes measurements, assesses safety, and issues an inspection report.
What an inspection report should contain and how to find the next deadline
An inspection report tells you not only the current condition of the installation but also when the inspection must be repeated. The deadline for the next periodic inspection should be included, usually in the conclusion, either as an interval (“4 years”) or a specific deadline (“by 03/2029”). If it is missing, the report is incomplete. The article Inspection report requirements summarises everything an inspection report should contain.
The report also lists any defects found. Ordinary defects do not usually prevent continued operation, but they should be remedied within a period determined by their severity and the inspection technician’s conclusion. Defects posing an immediate threat to safety mean that the equipment should not be used until it has been repaired and retested. The inspection technician then sets the next periodic inspection date according to the scope of the work and the equipment’s operating regime.
Who is responsible for monitoring the deadlines
In practice, this is the greatest stumbling block. Responsibility lies with the equipment operator—the company, owners’ association, municipality, or school using the electrical installation. It is not enough to assume that “the inspection technician will call.” The technician performs the inspection when commissioned, but the operator must monitor the deadline.
Within organisations, this is usually the responsibility of the statutory representative, technical manager, or person appointed to manage occupational health and safety documentation. This is precisely why it makes sense to have a system that monitors inspection deadlines. As part of our occupational health and safety services for businesses, we can also maintain an overview of your inspection deadlines, so you do not have to worry about missing one.
What happens if an inspection expires
The consequences of an expired inspection fall into three categories, none of them pleasant:
1. Legal and financial penalties. The inspektorát práce or hasičský záchranný sbor may impose a fine during an official check under zákona č. 251/2005 Sb. The amount depends on the severity of the findings, and the upper penalty limits changed through amendments from 1 January 2026, so the current wording of the law should always be consulted. The absence of a valid inspection report is considered one of the more serious findings.
2. Insurance consequences. If damage occurs, such as a fire or injury, and there is no valid inspection, the insurer may reduce or refuse payment depending on the agreed policy terms. The article Missing inspections and insurance claims explains how evidence of an inspection is treated when a claim is made.
3. Criminal liability. In the event of serious injury or death, investigators examine whether the operator fulfilled its obligations to ensure safe operation. The inspection report is one of the documents considered during that assessment.
Electrical installations, appliances, photovoltaic systems, and lightning protection—four different inspections
A fixed electrical installation inspection does not cover everything in a business that uses electricity. The following are subject to separate regimes, each with its own interval, standard, and report:
- appliances and handheld tools such as kettles, chargers, extension leads, and drills under ČSN 33 1600 ed. 2,
- rooftop photovoltaic systems as electrical equipment requiring separate inspection of both their DC and AC sections,
- lightning conductors and lightning protection systems under ČSN EN 62305, with intervals based on the protection class.
A new edition, ČSN EN IEC 62305 ed. 3, has also been published for lightning protection since autumn 2025. It applies concurrently with ed. 2 until 31 October 2027, after which only ed. 3 will apply.
Do not confuse these inspections. Appliance inspections and fixed-installation inspections are two different things, and neither replaces the other. Each has its own interval and report and must be monitored separately.
How to keep your inspections under control
The solution is simple: work with one reliable partner who understands both electrical systems and occupational safety and can manage your deadlines and documentation. That is how we work at SOHE—we handle inspections of electrical installations, lightning protection systems, appliances, and photovoltaic systems under one roof. Add occupational health and safety and fire protection, and you will no longer need to coordinate several contractors, while all the individual documents will fit together.
Pricing depends on the scope of the work. A smaller business unit or office typically starts at around CZK 2,500, while larger properties are priced according to the number of circuits and switchboards. Inspection of a single switchboard starts at approximately CZK 1,000. We will always provide the exact price in advance after a no-obligation enquiry.
Sources used for this article
- Electrical installation inspections – a SOHE service.
- Electrical installation inspections in industrial buildings – the stricter regime applying to production facilities and warehouses.
- Switchboard inspections – the switchboard as the core of every electrical installation inspection.
- Zákon č. 262/2006 Sb., ve znění pozdějších předpisů – zákoník práce; § 101 and § 102.
- Zákon č. 309/2006 Sb., ve znění pozdějších předpisů – § 4 requires regular maintenance, checks, and inspections of technical equipment.
- Zákon č. 250/2021 Sb., ve znění pozdějších předpisů – safe operation of designated technical equipment.
- Nařízení vlády č. 190/2022 Sb., ve znění pozdějších předpisů – designated electrical equipment and safety requirements; příloha č. 4 – maximum periodic inspection intervals.
- Nařízení vlády č. 194/2022 Sb., ve znění pozdějších předpisů – professional competence and who may perform inspections.
- Zákon č. 251/2005 Sb., ve znění pozdějších předpisů – labour inspection, supervision, and penalties.
This article is provided for information only and does not constitute legal advice. The specific inspection regime must be established according to actual operations, the manufacturer’s documentation, the operating environment, and the risk assessment.
Would you like to check whether your inspections are in order or consolidate your deadlines into a single plan? Contact us through our no-obligation enquiry form, email info@sohe.cz, or call +420 724 689 762. We will inspect the wiring at your premises and set future deadlines tailored to your operations.
We provide electrical installation inspections for businesses from approximately CZK 2,500 and single-switchboard inspections from CZK 1,000. We offer prompt appointments in Brno and the South Moravian Region—see Electrical inspections in Brno for details and our price list for indicative pricing.