How a Company Electrical Inspection Works

A company electrical inspection can be ordered on the assumption that “an inspector will turn up, take a few measurements, and send a report.” Then, at half past nine in the morning, the circuit supplying the server is switched off, the warehouse security control panel starts beeping, and the production manager discovers that the line needs an hour to restart. Most situations like these can be avoided if the client understands what the inspector will do during the day and what they will need.

This article explains the inspection process from the perspective of the company ordering it. The intervals between periodic inspections are covered separately in Company electrical inspections: intervals by premises; here, the focus is on what happens before, during, and after an inspection.

What an inspection is and who may perform it

Zákon č. 250/2021 Sb., o bezpečnosti práce v souvislosti s provozem vyhrazených technických zařízení defines an inspection in § 2(c) as an assessment of the operational and technical safety of equipment, using visual examination, testing, or measurement to verify whether the equipment complies with occupational health and safety regulations. Electrical installations in buildings and technologies are classified as designated electrical equipment under § 3(1) of nařízení vlády č. 190/2022 Sb.

Under § 17 of zákon č. 250/2021 Sb., an inspection may only be performed by an electrical inspector holding a certificate covering the type of equipment being inspected. If inspections are provided as a business activity, the inspector must also hold an authorisation under § 7(2) of the same law. The certificate is issued after an examination conducted by an authorised organisation and remains valid for five years from its issue date (§ 11(3)). The same certificate is required for electrical equipment by § 9 of nařízení vlády č. 190/2022 Sb.

For the client, this means carrying out one simple check: ask for the certificate registration number and verify both its scope and expiry date. The authorised organisation maintains a register of electrical inspectors and provides public remote access to their names, certificate scopes, and certificate expiry dates (§ 18(4) of zákon č. 250/2021 Sb.).

Initial, periodic, or extraordinary inspection

The type of inspection is stated in the report and also affects how the day proceeds:

• An initial inspection is performed before equipment is put into service, typically for a new installation or following its alteration. In addition to taking measurements, the inspector compares the completed installation with the design or drawings and checks that the accompanying documentation is complete (Annex 2, Part B, Section I of nařízení vlády č. 190/2022 Sb.).
• A periodic inspection is repeated at the intervals specified in the inspection, maintenance, and testing schedule. The inspector also assesses changes made since the previous inspection (Annex 2, Part B, Section II).
• An extraordinary inspection is conducted for a specific reason, such as work on the installation, a fault, or an incident. Its documentation includes a record stating the reasons for the inspection (Annex 2, Part A, Section II(g)), and the report states this reason.

Under § 6(4) of nařízení vlády č. 190/2022 Sb., an inspection is also required when changing a parameter relating to overload and short-circuit protection or protection against electric shock. The circumstances in which building alterations require an initial inspection are covered in Electrical inspections after refurbishment.

Before the inspection: scope and documentation

The inspection begins before the inspector arrives, with a clear definition of its scope. The inspection scope is a mandatory part of the report (§ 10(1)(c) of nařízení vlády č. 190/2022 Sb.). If it is not specified in the order, you will be unable to compare quotations or later establish whether the inspection also covered the warehouse, outdoor lighting, or the tenant’s wiring.

The order should specify at least:

• which buildings, floors, and distribution boards are to be inspected,
• whether it is an initial, periodic, or extraordinary inspection,
• whether the scope also includes the lightning protection system, photovoltaic installation, or electrical appliances, as these are separate inspection scopes,
• when circuits may and may not be switched off.

The documentation required by the inspector is listed in Annex 2 of nařízení vlády č. 190/2022 Sb. It includes drawings, a report defining external influences, the previous inspection report, and records of corrected defects. What to do if some of these documents are missing is explained in detail in Electrical inspections without documentation: what to prepare. Send the documents in advance so that the inspector can plan the procedure and estimate how many circuits will need to be switched off.

Inspection day, part one: visual examination

Under Annex 1 of nařízení vlády č. 190/2022 Sb., the visual examination takes place before testing. The inspector examines distribution boards and premises and checks, among other things:

• the condition of protection against electric shock, including enclosures, partitions, and barriers,
• the selection of conductors and protective devices and their settings,
• the choice of equipment in view of external influences, such as in wet operations or dusty workshops,
• the labelling of circuits, fuses, switches, and terminals,
• diagrams and warning labels on distribution boards,
• how conductors are connected,
• whether equipment is accessible for operation and maintenance.

In practice, the final point is primarily the client’s responsibility. An inspector cannot examine a distribution board obstructed by pallets, shelving, or boxes of office paper and will record inadequate access as a deficiency. Have the area in front of every distribution board covered by the inspection cleared the day before.

The visual examination does not usually disrupt operations. However, the inspector will open distribution boards and remove covers, so people without appropriate electrical qualifications should not be in the immediate vicinity.

Inspection day, part two: testing and measurement

Annex 1, Part B of nařízení vlády č. 190/2022 Sb. specifies what must be tested and measured during an inspection and also sets the order. In simplified terms, this includes the following tests:

• continuity of protective conductors and bonding – whether metal parts and protective contacts are properly connected to earth,
• insulation resistance – whether conductor insulation allows current to flow where it should not,
• automatic disconnection of supply – whether a circuit breaker or other protective device disconnects the circuit quickly enough in the event of a fault,
• residual current devices and other protective equipment – whether they trip correctly,
• functional tests – for example, of emergency shutdowns or interlocks,
• polarity and phase sequence, and, where applicable, voltage drop and thermal effects,
• operation of surge protective devices.

The limit values are defined by technical standards, particularly the ČSN 33 2000 series; the measured values will appear in the report. If a particular visual check or test is not technically feasible for the equipment concerned or is not justified for verifying safety, it is not required (§ 7(3) of nařízení vlády č. 190/2022 Sb.). A good report states what was omitted and why.

Why the inspector switches circuits off and how to plan the outage

Some measurements are taken with the power on, while others are not. Insulation resistance is generally measured on a de-energised circuit with appliances disconnected, as the test voltage could damage them and the appliances could also distort the result. Testing a residual current device deliberately disconnects the circuit. Consequently, individual circuits will be switched off one after another during the inspection; with smaller distribution boards, the entire board may occasionally be shut down.

How many circuits will be affected, and for how long, depends on the size of the installation and how well the circuits are labelled. After reviewing the documentation, the inspector can say which distribution boards must be switched off completely and which can be measured circuit by circuit. Use this information to prepare your plan.

The following measures work well in practice:

1. A list of critical equipment with the name and telephone number of the person responsible.
2. A timetable organised by distribution board, rather than simply “inspection all day.” People will then know when they will lose power.
3. A notice to employees the day before, allowing them to save their work and find out when their sockets will be without power.
4. An off-peak appointment, typically before the morning shift, on Friday afternoon, or at the weekend if required by the scope.

If nothing can be switched off, for example in a continuous operation, this must be stated in the initial enquiry. The inspector can then propose a suitable procedure and define in the report what could and could not be verified.

Who should be available from the company

The inspection requires someone who knows both the building and its operations. Ideally, this should be the person responsible for the electrical equipment. The operator of designated electrical equipment must appoint this person in writing, and their duties include ensuring safe operation (§ 8(d) of nařízení vlády č. 190/2022 Sb.). In a smaller company, this is often a maintenance technician or operations manager; in leased premises, it may be the building manager.

The following people should be on site or available by telephone:

• a contact person with keys to distribution board cabinets, electrical rooms, plant rooms, roofs, and warehouses,
• the IT administrator, who can shut down and restart servers and the network,
• the production manager or process engineer, who decides when a machine may be stopped,
• the building manager or landlord’s representative, if some of the wiring belongs to the landlord,
• someone familiar with changes made since the previous inspection.

Also prepare access cards, codes, and authorisation to enter tenants’ premises. An hour spent looking for the electrical room key will add to both the time and the cost.

If the inspector discovers a dangerous condition

Most defects are recorded in the report and addressed after the inspection. The exception is a condition that presents an immediate risk to occupational or operational safety, such as an exposed live part or a terminal damaged by heat. Under § 7(8) of nařízení vlády č. 190/2022 Sb., such equipment must be disconnected from the power supply immediately and secured against unintended reconnection. If this is not possible, it must be repaired without undue delay.

You should therefore allow for the possibility that the inspection will end with part of the operation being disconnected. Agree in advance who within the company is authorised to make this decision and which electrician you will call. What to do after an unsatisfactory conclusion is explained in Electrical inspection failed: what next.

After the inspection: the inspection report, defects, and next due date

The inspection report is not produced on site. The inspector prepares it from the visual examination and measured values. Under § 10(1) of nařízení vlády č. 190/2022 Sb., it includes, among other things:

• the start and end dates of the inspection and the dates on which the report was prepared and delivered,
• a list of the source documents and the work performed,
• measured values and a list of measuring instruments,
• a summary of the defects identified, including the regulations breached,
• a written assessment of whether the equipment is safe to operate,
• a recommended interval before the next inspection,
• confirmation that the report was received or handed over.

A complete list of requirements can be found in Inspection report requirements, with practical guidance on defects in How to read an electrical inspection report.

After receiving the report:

1. Read the conclusion and list of defects and sort them by urgency.
2. Arrange repairs and ask the electrician to document what was done and where.
3. Enter the next inspection date in your calendar according to the interval in the inspection, maintenance, and testing schedule. If the manufacturer’s accompanying documentation specifies a shorter interval, that interval applies (§ 7(2) of nařízení vlády č. 190/2022 Sb.).
4. Add the report to the operating documentation, together with records showing that defects have been corrected. The next inspector will want to see them.

If you are interested in the condition of connections inside distribution boards under full load—a situation that an inspection involving circuit shutdowns will not reveal—see thermal imaging of distribution boards.

Sources for this article

• Electrical inspections – a service provided by SOHE.
• Electrical inspections without documentation: what to prepare – which documents the inspector needs and what to do if they are missing.
• Inspection report requirements – what the report must contain and how to recognise an invalid document.
• Company electrical inspections: intervals by premises – how often inspections are repeated.
• Zákon č. 250/2021 Sb. – occupational safety in connection with the operation of designated technical equipment, the definition of an inspection, and electrical inspectors and their certificates.
• Nařízení vlády č. 190/2022 Sb. – designated electrical equipment, the scope of visual examinations and testing, inspection documentation, and the contents of inspection reports.
• The ČSN 33 2000 series – low-voltage electrical installations, including inspections.

This text is for information only and does not constitute legal advice. The specific inspection and shutdown arrangements must reflect the actual operation, the manufacturer’s documentation, the environment in which the equipment is used, and the risk assessment.

Are you planning an electrical inspection and need to minimise disruption to your operations? Send us a no-obligation enquiry describing the premises and any shutdown restrictions, or email info@sohe.cz.