What is an Electrical Inspection Condition Report

An Electrical Installation Condition Report (EICR) is a comprehensive inspection and test of a property's electrical installation to ensure it's safe and fit for continued service. It assesses the condition of wiring, sockets, consumer units (circuit breaker or fuse boards), and other fixed electrical parts, identifying any potential hazards or defects.

Key aspects of an EICR:

• Inspection and Testing:

  A qualified approved electrician inspects the electrical installation visually and then conducts a series of tests to check its safety.

• Assessment of Hazards:

  The EICR can identify potential risks like electric shock, fire or other hazards.

• Recommendations:

  The report provides recommendations for repairs or improvements to address any identified issues.

• Compliance:

  EICRs are often required for landlords to comply with regulations, ensuring their rental properties are electrically safe.

• Who requires an E.I.C.R?:

  Anyone Who Owes a Duty of Care:

  The duty of care to maintain a safe environment is a legal obligation that applies to landlords and business owners. This includes ensuring that all electrical installations are safe.

In summary, anyone who owns or operates a building where people work or live has a duty to ensure the electrical installations are safe and comply with relevant regulations. This often translates into the need for an EICR.

What to expect during an EICR:

1. 1. Visual Inspection:

   The electrician will visually examine the electrical components, looking for signs of damage or deterioration in order to ascertain if its safe to continue to the electrical tests.

2. 2. Electrical Tests:

   They will conduct various tests, including continuity checks, insulation resistance tests, and earth fault loop impedance tests.

3. 3. Report Generation:

   A detailed EICR report will be generated, summarizing the findings and recommendations.

4. 4. Remedial Work:

   If any defects are identified, the electrician may recommend repairs or upgrades to address them.

In essence, an EICR is a safety check to ensure your property's electrical installation is functioning safely and meeting current standards, helping to prevent accidents and comply with regulations.

The sequence to conduct a three phase E.I.C.R.

Conducting a three-phase Electrical Installation Condition Report (EICR) involves a systematic sequence of visual inspections and dead and live electrical tests to assess the safety and condition of the entire system

.The procedure is more complex than a single-phase EICR due to the multiple live conductors and is based on the IET Wiring Regulations (BS 7671).

Pre-inspection steps

1. Preparation and client consultation: Discuss the purpose, extent, and limitations of the EICR with the client. For instance, agree on which areas and accessories will be inspected, as well as the need for any shutdowns.

2. Gather documentation: Collect any previous reports, certificates, or diagrams for the installation.

3. Site assessment: Before any testing, conduct a walk-through to identify the main switch, distribution boards, all circuits, and potential safety hazards.

Step 1: Visual inspection (Pre-energisation)

A thorough visual check is the first and most crucial step. The system must remain energised at this stage. Check for:

• Damaged, cracked, or improperly installed electrical equipment.

• Signs of overheating, such as discoloration on enclosures or wiring.

• Adequate access and working space around distribution boards and equipment.

• Correct labeling of circuits and protective devices.

• Condition of the enclosure, including any damage or missing parts.

• Evidence of alterations or additions since the last inspection.

• A representative number of terminations and connections at accessories like sockets and switches.

Step 2: Dead electrical tests

Isolate the entire electrical installation from the main supply before performing these tests. All connected loads and sensitive electronic equipment must be disconnected or isolated from the circuits under test.

1. Continuity of protective conductors: Use a low-resistance ohmmeter to confirm the continuity of all protective conductors, including main and supplementary bonding. For three-phase, test the continuity between the main earth terminal and the earth terminal of each piece of three-phase equipment.

2. Continuity of ring final circuit conductors (if applicable): If the installation contains ring circuits, test the continuity of the line, neutral, and earth conductors.

3. Insulation resistance testing: Set the insulation resistance tester to 500V DC. Test the insulation between:

   • Phase conductors L1, L2, L3 connected together, and the neutral and earth connected together.

   • L1 and L2, L1 and L3, and L2 and L3.

   • L1, L2, and L3 connected together, and the neutral.

   • Each phase conductor and earth individually.

   • Each phase conductor and neutral individually.

   • The neutral and earth conductors.

4. Polarity: On three-phase systems, ensure that phase conductors are correctly connected at all switchgear, distribution boards, and equipment. Incorrect polarity can cause damage to equipment.

Step 3: Live electrical tests

Restore the power supply to the installation with caution. Live testing must be carried out by a competent person using the appropriate test equipment.

1. External earth fault loop impedance (Ze):

   Disconnect the main earthing conductor and measure the impedance of the earth fault loop external to the installation. Record the highest reading from each phase.

2. Earth fault loop impedance (Zs):

   At the furthest point of each circuit, measure and record the earth fault loop impedance. This can be compared with the maximum allowable values for the protective device.

3. Prospective fault current (Ipfc):

   Measure the prospective fault current at the origin of the installation. This confirms that the protective devices have an adequate breaking capacity.

4. Residual Current Device (RCD) testing:

   Test all RCDs and RCBOs to verify they trip within the required time limits at 1x and 5x the rated tripping current.

5. Phase rotation:

   Use a dedicated phase rotation meter to check that the correct phase sequence (e.g., L1-L2-L3) is present at three-phase sockets and equipment. This is critical for motors to rotate in the correct direction.

6. Functional tests:

   Check the correct operation of all switches, isolators, and other controls.

Step 4:

Documentation and reporting

After completing all inspections and tests, document the findings accurately on the EICR form.

1. Record observations: List any observations, damage, or defects found during the inspection and testing.

2. Assign classification codes: Use the standard classification codes to indicate the severity of any issues:

   • C1: Danger present. Risk of electric shock or fire. Immediate remedial action is required.

   • C2: Potentially dangerous. Urgent remedial action is required.

   • C3: Improvement recommended. The installation is safe, but improvements are recommended to meet modern standards.

   • FI: Further investigation is required. Used when the extent of an issue cannot be determined at the time of the inspection.

3. Overall assessment: Based on the observations and codes, provide an overall assessment of the installation as either "Satisfactory" or "Unsatisfactory".

4. Recommendations: Clearly outline the necessary remedial actions in the report.

5. Certificate completion: Fill out all sections of the EICR form, including the supply characteristics, earthing arrangements, and test results, before issuing it to the client.

The Importance of Bonding Conductors

Bonding conductors connect metallic parts of an electrical installation and its surroundings to an earthing system to keep them at the same electrical potential, preventing dangerous voltage differences that could cause electric shock, sparks, or fires. By providing multiple paths for fault current and reducing overall loop impedance, bonding also helps protective devices operate more quickly, enhancing safety. There are two main types: main protective bonding, which connects the main water, gas, and structural steel, and supplementary bonding, which connects other metallic services and items in local areas like bathrooms and kitchens.

What bonding conductors do:

• Prevent Electric Shocks:

  The primary function of bonding is to reduce the risk of electric shock. When there's an electrical fault, bonding conductors ensure that all interconnected metal parts (like pipes and equipment casings) remain at the same potential, so a person touching two different metallic surfaces won't experience a significant voltage difference.

• Limit Touch Voltage:

  By connecting conductive parts to the earthing system, bonding helps to limit the magnitude of the touch voltage that could appear on these parts during a fault.

• Enhance Fault Current Path:

  Bonding provides parallel paths for fault currents, which reduces the overall resistance of the fault loop.

• Speed up Protective Device Operation:

  A lower fault loop impedance results in a higher fault current, which causes protective devices like fuses or circuit breakers to trip and disconnect the power supply more quickly, further protecting people from harm.

• Control Spark Ignition:

  In potentially flammable environments, bonding is essential to prevent the ignition of flammable gases or dust by static electricity or arcing.

Types of bonding:

• Main Protective Bonding:

  This connects the main earthing terminal to the structural steel, metallic water, gas, and oil pipes entering the building.

• Supplementary Bonding:

  This connects other metallic services and parts together, such as metallic water pipes, gas pipes, and electrical services in high-risk areas like bathrooms and kitchens, to ensure they are at the same potential as the earthing system.

How to resolve high Zs readings within industrial and commercial premises.

What is Zs and why does it matter for electrical safety.

Zs stands for total earth fault loop impedance. It is a critical measurement in electrical installations that determines the total opposition to the flow of current in the event of an earth fault (a live wire touching a metal part).

Why Zs Matters for Electrical Safety

The value of Zs is vital for electrical safety because it directly ensures the automatic disconnection of the power supply in a timely manner, preventing electric shocks and fires.

• Ensures Protective Device Operation: Fuses and circuit breakers need a specific amount of current to flow to "trip" or blow within a required safe time (typically 0.4 seconds for socket circuits and 5 seconds for fixed equipment in the UK). This required current is determined by the circuit's Zs value and the supply voltage (using Ohm's law: Current = Voltage / Zs). * AC Theory would also include a phase angle component.

• A High Zs is a Safety Hazard: If the Zs reading is too high, the fault current will be insufficient to activate the protective device quickly enough. This means an earth fault could remain live for a dangerous period, leading to:

  • An increased risk of electric shock if someone touches an earthed metal part (like an appliance casing) that has become live.

  • A potential fire risk due to the sustained flow of current heating up the wiring or faulty component.

• Compliance with Standards: Electrical safety regulations, such as the BS 7671 in the UK, specify maximum permissible Zs values for different types and ratings of protective devices. An electrician must test and verify that the measured Zs value of a circuit is below the specified maximum to ensure compliance and safety.

• Verifies Earthing System Effectiveness: The Zs test confirms that there is a continuous and effective earth connection from the installation's main earth terminal all the way back to the supply transformer.

Regular testing and measurement of Zs are essential parts of electrical installation and maintenance to verify that these crucial safety mech

.BS 7671 does not specify a fixed maximum disconnection time for phase to neutral overloads in the same way it does for earth faults. Instead, the requirements for overload protection focus on ensuring that any persistent small overload of long duration is disconnected before it causes thermal damage to the circuit conductors.

The primary mechanism for this is proper coordination between the conductor's current-carrying capacity and the protective device's characteristics, as detailed in Regulation 433.1, which states:

• The rated current or current setting of the protective device (In)must not be less than the design current (Ib)of the circuit.

• The rated current or current setting of the protective device (In) must not exceed the lowest current-carrying capacity (Iz) of any conductor in the circuit.

The actual disconnection time for a given overload current is determined by the specific time/current characteristics of the protective device (e.g., BS EN 60898 circuit breaker) used, as provided by the manufacturer. This time could be several seconds, minutes, or longer for a marginal overload (e.g., a current just above In) as long as it is within the limits that prevent conductor damage.

In contrast, the specific, rapid disconnection times (e.g., 0.4s for final circuits in TN systems, 0.2s for TT systems) are primarily for automatic disconnection in case of an earth fault to protect against electric shock, not for overload protection.

Important note regarding the automatic disconnection of supply in the event of an earth fault.

When we measure Zs we cannot be assured of the fitness of purpose of the system by the value alone.

The

adiabatic equation is primarily used to ensure thermal safety of the protective conductor, which in turn supports touch safety by ensuring the earthing system remains intact during a fault. It determines the minimum size of the earthing conductor required to withstand the heat generated by a fault current without reaching temperatures that could cause damage or failure.

The equation is: S= (√ I²t)/k
Where:

𝑆= Minimum cross-sectional area (CSA) of the protective conductor in mm2

I = The prospective earth fault current in Amperes (A)

t = The disconnection time of the protective device in seconds (s).

k = A factor that accounts for the conductor material, insulation type, and initial/final temperatures.

One option to consider ( If the overcurrent protection cannot be reduced due to circuit load) would be Moulded Case Circuit Breakers (MCCBs) with integrated Residual Current Device (RCD) protection

These devices are often referred to as three-phase RCBOs (Residual Current Circuit Breaker with Overcurrent protection) or CBRs (Circuit Breakers with integral RCD).

How they work and where they are used

• Functionality: These combined units offer both overcurrent protection (like a standard MCCB or MCB) and earth leakage protection (RCD) in a single device.

• Mechanism: In a three-phase system, the RCD function works by detecting any imbalance in current across the three live phases (and neutral, if present). In a healthy circuit, the sum of the currents at any instant is zero. If there is an earth leakage, this balance is lost, causing the device to trip and disconnect all live conductors, including the neutral, if it is a 4-pole unit.

Alternatives

If an all-in-one unit is not available or practical for a specific installation, RCD protection can be achieved using a separate RCD (also known as an RCCB) placed upstream of the MCCB, or by using a core balance earth leakage sensor to trip the MCCB via a shunt or under-volt release coil.

The operation of core balance earth leakage sensors is beyond the scope of this article.

How does a three-phase Moulded Case Circuit Breaker (MCCB) with integrated or associated RCD protection assist in meeting earth fault disconnection times required by BS7671

In some scenarios, particularly in TT earthing systems or installations where the earth fault loop impedance (Zs) is high, an MCCB alone may not be able to achieve the mandatory rapid disconnection times, making the RCD a critical component for safety.

How RCD Protection Helps

• Sensitivity: Standard circuit breakers (MCBs/MCCBs) rely on a high fault current flowing to earth to trip within the required time. RCDs, however, are far more sensitive, detecting much smaller residual currents (e.g., 30 mA, 100 mA). This low sensitivity allows them to operate even when the earth fault loop impedance is too high for the MCCB's overcurrent element to trip fast enough.

• Rapid Disconnection: RCDs are designed to trip very quickly when their rated residual operating current (IΔn) is exceeded. For general, non-time-delayed RCDs used for fault protection, the maximum disconnection time is typically less than 300 ms at IΔn and often faster at higher fault currents, easily meeting the 0.4 second (400 ms) or even 0.2 second (200 ms for certain TT systems) limits required by BS 7671 for final circuits.

• Enabling Compliance in Difficult Systems: In TT earthing systems, the earth fault loop impedance can be inherently high. RCDs are therefore essential for providing automatic disconnection of supply (ADS) in these situations, as the impedance values are often too high for a standard overcurrent device (MCCB) to meet the disconnection times.

• Additional Protection: RCDs with a rated residual operating current not exceeding 30 mA are also used to provide additional protection against electric shock in specific circumstances, such as for socket-outlets and circuits supplying equipment in a bathroom, with a required operating time of 40 ms at 5 times IΔn.

Key Considerations

• Disconnection Times: BS 7671 specifies different maximum disconnection times depending on the circuit type and earthing system (e.g., 0.4s for most final circuits in TN systems, 0.2s for final circuits in TT systems, and up to 5s for distribution circuits). The RCD's characteristics must be appropriate for the required time.

• Discrimination/Selectivity: When using multiple RCDs in series, time-delayed (Type S) RCDs may be installed upstream to ensure the RCD closest to the fault trips first, providing selectivity. Note that time-delayed RCDs cannot be used for additional protection requirements as their trip times are longer.

• Type Selection: The correct type of RCD (Type AC, A, F, or B) must be selected based on the characteristics of the connected equipment (e.g., presence of DC components, variable speed drives) to ensure it operates correctly and is not "blinded" by certain fault currents. Manufacturers' data must be consulted for specific information on selection and application.

In conclusion, an RCD integrated with an MCCB is a highly effective solution for ensuring earth fault disconnection times comply with BS 7671, particularly where the natural earth loop impedance prevents standard overcurrent protection from achieving the necessary rapid disconnection.Reputable manufacturers such as Chint, Hager, and Niglon offer these types of integrated solutions. You can find various options from suppliers like

Proper selection and installation of these devices should be performed by a qualified electrician to comply with all relevant wiring regulations, such as the UK's BS 7671.