3.3 Schedule of Test Results, Circuit Details & Instrument Data

3.3 Schedule of Test Results, Circuit Details & Instrument Data

The Schedule of Test Results is the quantitative core of an Electrical Installation Condition Report (EICR). Dictated by BS 7671 Appendix 6 and detailed in IET Guidance Note 3 (GN3), this schedule tabulates the physical design parameters of every final circuit and sub-main alongside the empirical values measured during dead and live electrical testing. Accurate completion of this schedule provides the technical evidence required to verify automatic disconnection of supply (ADS), conductor current-carrying capacities, insulation degradation, and earth fault loop impedance compliance.

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Anatomy of the Schedule of Test Results Columns

+---------------------------------------------------------------------------------------------------+
|                                 SCHEDULE OF TEST RESULTS COLUMNS                                  |
+---------------------------------------+-----------------------------------------------------------+
| CIRCUIT DETAILS & DESIGN PARAMETERS   | EMPIRICAL TEST RESULTS (DEAD & LIVE TESTING)              |
+---------------------------------------+-----------------------------------------------------------+
| - Circuit Number & Description        | - Continuity: r1, rn, r2 (Ring End-to-End)                |
| - Reference Installation Method       | - Continuity: R1+R2 or R2 (Circuit Protective Conductor)  |
| - Live / CPC Conductor Sizes (mm²)    | - Insulation Resistance: Live-Live & Live-Earth (MΩ)      |
| - Overcurrent Device: Type, Rating, Icn| - Polarity Verification (✓)                              |
| - RCD: Operating Type, Rated IΔn (mA) | - Earth Fault Loop Impedance: Measured Zs (Ω)             |
|                                       | - RCD Disconnect Time: at 1x IΔn (ms) & Test Button (✓)   |
+---------------------------------------+-----------------------------------------------------------+

Circuit Details & Design Data Columns

1. Circuit Number & Description: Identifies the physical load fed by the circuit (e.g., "Circuit 1: Ground Floor Ring Final Sockets," "Circuit 2: 1st Floor Lighting Radial").
2. Reference Method: Identifies the installation method per BS 7671 Appendix 4 (e.g., Method A for enclosed in conduit in thermally insulating wall, Method C for clipped direct).
3. Conductor Cross-Sectional Area ($mm^2$): Sizing of Line ($r_1$), Neutral ($r_n$), and Circuit Protective Conductor ($cpc$).
4. Overcurrent Protective Device Data:
   • Type & Standard: e.g., BS EN 60898 Type B MCB, BS EN 61009 RCBO, BS 88-2 cartridge fuse.
   • Rating ($I_n$): Nominal current rating in Amperes (e.g., 6A, 16A, 32A).
   • Short-Circuit Capacity ($I_{cn}$): Maximum breaking capacity in kA (e.g., 6kA, 10kA).
5. RCD Characteristics: Rated residual operating current ($I_{\Delta n}$ in mA, e.g., 30mA) and operating type (Type AC, Type A, Type F, Type B).

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Empirical Test Result Documentation

1. Conductor Continuity & Ring Circuit Verification

For radial circuits, inspectors record either the combined line and protective conductor resistance ($R_1+R_2$) or the protective conductor resistance alone ($R_2$). For ring final circuits, three distinct end-to-end resistance readings must be recorded in the schedule:

• $r_1$: End-to-end resistance of the line conductor loop.
• $r_n$: End-to-end resistance of the neutral conductor loop.
• $r_2$: End-to-end resistance of the circuit protective conductor (cpc) loop.

Following end-to-end tests, cross-connection of the line and cpc loops (Step 3 test) yields a figure-of-eight resistance profile at each socket outlet. The highest reading recorded across the ring is documented as the circuit $R_1+R_2$, which mathematically correlates to:

$\text{Maximum } R_1+R_2 = \frac{r_1 + r_2}{4}$

2. Insulation Resistance Testing

• Recorded in Megohms ($M\Omega$).
• Test voltage applied: 500V DC for standard low-voltage (230V/400V) circuits, 250V DC for SELV/PELV systems or where sensitive electronic equipment is connected.
• Minimum acceptable threshold per BS 7671 Table 64 is $1.0\text{ M}\Omega$.

GN3 Rule of Thumb: While $1.0\text{ M}\Omega$ is the absolute statutory minimum pass limit, GN3 highlights that any reading below $2.0\text{ M}\Omega$ in a modern or dry installation warrants further investigation, as it indicates moisture ingress or insulation degradation.

3. Earth Fault Loop Impedance ($Z_s$) & Temperature Correction

Measured $Z_s$ values recorded on the schedule must be compared against the maximum permitted $Z_s$ values tabulated in BS 7671 Chapter 41. Because tabulated values represent conductors operating at their maximum permitted temperature (e.g., 70°C for PVC insulation), values measured during testing at ambient temperature (typically 20°C) must be corrected using the 0.8 multiplier:

$Z_s \text{ (measured at ambient)} \le 0.8 \times Z_s \text{ (tabulated max in BS 7671)}$

If the measured ambient $Z_s$ exceeds $80%$ of the tabulated limit, the circuit fails ADS compliance criteria unless ambient temperature correction calculations per GN3 Appendix B prove compliance.

+-----------------------------------------------------------------------------------+
|                    MAXIMUM TABULATED Zs vs 80% AMBIENT LIMIT                      |
+-----------------------+--------------------------+--------------------------------+
| DEVICE TYPE & RATING  | TABULATED MAX Zs (CH 41) | 80% AMBIENT LIMIT (TEST PASS)  |
+-----------------------+--------------------------+--------------------------------+
| 6A Type B MCB         | 7.28 Ω                   | 5.82 Ω                         |
| 16A Type B MCB        | 2.73 Ω                   | 2.18 Ω                         |
| 32A Type B MCB        | 1.37 Ω                   | 1.09 Ω                         |
| 32A Type C MCB        | 0.68 Ω                   | 0.54 Ω                         |
+-----------------------+--------------------------+--------------------------------+

4. RCD Disconnect Testing

• Operating Disconnect Time: Recorded in milliseconds (ms) when tested at $1 \times I_{\Delta n}$. Under BS 7671 Chapter 41, generic additional protection RCDs ($30\text{mA}$) must trip within 300ms at $1 \times I_{\Delta n}$.
• Integral Test Button: Verification that pressing the manual test button operates the mechanical trip mechanism (recorded as a tick $\checkmark$).

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Test Instrument Serial Numbers & BS EN 61557 Compliance

To ensure legal defensibility and measurement integrity, the Schedule of Test Results requires explicit documentation of the test equipment used:

• Instrument Data Fields: Make, model, and individual serial numbers for Multifunction Testers (MFTs) or standalone meters (Continuity/Insulation, Loop Impedance, RCD testers).
• Standard Compliance: All test instruments used for periodic inspection must conform to the relevant part of the BS EN 61557 series (Parts 1 through 10).
• Calibration & Accuracy Checks: Inspectors must hold current formal annual calibration certificates for all instruments. Between formal annual calibrations, inspectors must maintain an in-service accuracy logbook, recording regular weekly/monthly checks using dedicated calibration check boxes or fixed reference test boards to verify instrument accuracy and detect drift.