OP
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Again the extent and limitations of the report needs to be stated and recommendations of defects and their remedies should be made.
The report includes a numbering system for this purpose, as follows: 1 - Requires Urgent Attention; 2 - Requires Improvements; 3 - Requires Further Investigation; and 4 - Does Not Comply With BS 7671:2008 (although this does not necessarily imply that the electrical installation is unsafe).
Several associations and trade bodies allow the issuing of a Minor Works Certificate.
A minor works is defined as 'work which does not include the provision of a new circuit'.
Testing is still essential and a number of tests are specifically identified as essential to confirm safety.
Also included on the form is space to allow the inspector to comment on the existing installation.
In a practical sense, for most electrical contractors involved in installation testing, the most frustrating part of the job is the recording of test data onto test certificates.
Invariably, current working practices involve the printing out or copying of a certificate for all premises to be tested at the beginning of the working day.
As circuit testing is undertaken on site the electrician will then usually record details of the inspection with written information on the 'dummy' certificate.
At the end of the day, back in the office, the manually recorded results will then be transferred to an 'original' certificate for the customer.
When Must The Tests Be Carried Out ? IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
The International Standard IEC-603664-6 Provides Requirements for “ Initial Verification “ and “ Periodic Verification “
Of an Electrical Installation :
“ Initial Verification “ Consists of Visual Inspection & Testing , of an Electrical Installation to Determine , as far as Reasonably Practicable , whether the Requirements’ of the Other Parts of IEC-60364 have been Met , Including Requirements for the Reporting of the Testing Results ,
The Initial Verification takes Place Upon Completion of a New Installation or Completion of Additions or of Alterations to Existing Installations ,
Periodic Verification : Provides the Frequency and the Requirements’ for Periodic Verification of an Electrical Installation to Determine ,
As far as Reasonably Practicable , Whether the Installation and all its Constituent Equipments are in a Satisfactory Condition for Use ,
Including Requirements for the Reporting of the Testing Results , Chapter 7 of this Guide Reports some Consideration of Periodic Inspection ,
This Guide will Not-Consider Visual Inspections ( for example the Checking of the Method of Protection Against the Electric Shock like Barriers
And Distances , Colour and Size of the Conductors , Presence of the Diagrams , Appropriate Selection of Materials , etc . )
But will Focus on the Various Testing Regimes and the Stipulated Values which these Tests should Deliver ,
Requirements For Testing An Electrical Installation :
The Following Tests shall be Carried Out where Relevant and should Preferably be Made in the Following Sequence :
* Continuity of the Protective Conductors and of the Main and Supplementary Equipotential Bonding Conductors :
* Insulation Résistance of the Electrical Installation :
* Protection by SELV & PELV or by Electrical Separation :
* Insulation Résistance of Non-Conducting Floors and Walls :
* Verification of Conditions for Protection by Automatic Disconnection of the Supply -
( Fault Loop Impedance , Earth Résistance , RCD Tests )
* Polarity and Phase Sequence Tests :
* Functional and Operational Tests :
* Voltage Drop :
The International Standard IEC-60364-6 Requires that all Measuring Instruments and Monitoring Equipment Used for the above Tests Comply with the Series IEC/EN 61557 , if Other Testing Equipment is Used , it shall Provide the Same Degree of Performance and Safety as a Minimum ,
Electrical Systems : “ Experiment “
An Electrical System Consists of a Single Source of Electrical Energy and an Installation ,
Depending on the Relationship between the Source and the Exposed ( Conductive ) Part of the Installation to Earthing ,
The Standards define the Type of System as Follows :
TT , System : the Accessible Conductive Parts are Earthed Indepently of the Source Earth :
TT : L1 ─────────────── ------- ────────────────────
……. L2 ─────────────── ------- ────────────────────
……. L3 ── * ──────────── ------- ───*──────────────── ( Single Phase )
…….. N ── * ──────────── ------- ───*──────────────── ( PE ) – ( R ) – Earthing
Earthing Rod ,
IT – System : the Live Parts are Insulated from the Earth ( or Connected to Earth Through an Impedance Z )
The Accessible Conductive Parts are Earth Independently :
……………………………………. 3-Phase
IT : L1 … . ────────────────── -------- ────────────────
……. L2 … . ────────────────── -------────────────────
……. L3 … * ────────────────── ------- ──*────────── L3 - ( Single Phase
…….. N * ─↓──────────────── ------- ─────*─────── ( PE ) – R ( Earthing
.. ……………..... Z
Earthing
IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
Insulation Résistance of the Electrical Installation :
The Insulation Résistance shall be Measured between each Live Conductor and the Protective Conductor or Earth ,
In Locations Exposed to Fire Hazards , a Measurement of the Insulation Résistance between the Live Conductors’ shall be Taken
The Insulation Résistance , Measured with the Test Voltage Values Indicated in the Table below are Satisfactory if each Circuit , with the Appliances Disconnected , has an Insulation Résistance Not-Less than the Appropriate Value given in the same table ,
Nominal Circuit ………………………….. Test Voltage …………………………… Insulation Résistance
Voltage ………………………………………. d.c. ………………………………….
────────────────────────────────────────────────────────────────
SELV , PELV ………………………………… 250 v ……………………………………… ≥ 0.5MΩ
( ≤ 50 v a.c. ≤ 120 v d.c. )
────────────────────────────────────────────────────────────────
Up to & including 500 v ……………………… 500 v ……………………………………... ≥ 1 MΩ
( including FELV )
────────────────────────────────────────────────────────────────
Above 500 v …………………………………… 1000 v …………………………………….≥ 1 MΩ
────────────────────────────────────────────────────────────────
Typically for 230 / 400 v Circuits ( Excluding SELV & PELV ) IEC 60364-6 Requires that the Insulation Résistance at a Test
Voltage of 500 v d.c. shall be 1MΩ as a Minimum :
NOTE: Where Surge Protective Devices ( SPDs ) are Likely to Influence the Test or be Damaged ,
Such Equipment shall be Disconnected before Carrying Out the Insulation Résistance Test , Where it is Not Reasonably Practicable to Disconnect such Equipment ( e.g. in Case of Fixed Sockets-Outlets Incorporating an ( SPD ) the test Voltage for the Particular Circuit may be Reduced to 250 v d.c. , but the Insulation Résistance must have a Value of at Least 1MΩ
Protection by SELV , PELV or by Electrical Separation : 2392-10 / 2391-10
Even if the Automatic Disconnection of Supply by Circuits-Breakers , Fuses and RCDs , is Normally the most Common Protection Method . there are Other Protection Methods like Protection by SELV , PELV or be Electrical Separation or by Non-Conducting Floors and Walls ,
Only for these Cases shall the Separation of Live Parts from those of Other Circuits , be Confirmed by a Measurement of the Insulation Résistance , The Résistance Values Obtained must be in Accordance with table :
Below there is an Example of the Measured of Insulation Résistance to Confirm the Separation of Live Parts from those of Other Circuits :
Test Instrument : (1) One Lead On ( Between the Output of the Transformer ) 2-Wires
Test Instrument : (2) One Lead On ( And the Other Live-Parts – for SELV / PELV )
( And the Equipotential Bonding Rads ( SELV Only )
Insulation Résistance of Non-Conducting Floors and Walls :
When it is Necessary to Comply with the Requirements of the Protection by Non-Conducting Locations , the Floor and Wall Insulation Résistance / Impedance shall be Tested
In Part 6 of IEC 60364 Methods for Measuring the Insulation Résistance / Impedance of Floors and Walls are given as Example ,
IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
Verification of Conditions for Protection by Automatic Disconnection of the Supply :
Automatic Disconnection of the Supply is Required where a Risk of Harmful Pathophysiological Effects to a Person may arise due to a Fault as a Result of the Value and Duration of the Touch Voltage ,
The Verification of the Efficacy of the Measures for Protection against Indirect Contact by Automatic Disconnection of Supply is Treated below :
In Case of TN-systems :
According to the International Standard IEC 603664 , for TN- system the Characteristics of the Protective Device and the Circuit Impedance shall fulfil the following Requirements :
( Zs x Ia ≤ Uo )
Zs : is the Fault Loop Impedance in Ohms ,
Uo is the Nominal Voltage between Phase to Earth ( Typically 230 V AC for Single Phase & Three Phase Circuits ,
Ia is the Current Causing the Automatic Disconnection of the Protective Device within the Maximum Disconnecting Times Required by IEC 60364-41 that are :
- 400 ms for Final Circuits Not Exceeding 32A ( at 230 / 400V ac )
- 5s for Distribution Circuits and Circuits Over 32A ( at 230V / 400V ac )
The Compliance with the above rules shall be Verified by :
(1) Measurement of the Fault Loop Impedance ( Zs ) by Loop Tester :
(2) Verification of the Characteristics and / or the Effectiveness of the Associated Protective Device , This Verification shall be Made :
The report includes a numbering system for this purpose, as follows: 1 - Requires Urgent Attention; 2 - Requires Improvements; 3 - Requires Further Investigation; and 4 - Does Not Comply With BS 7671:2008 (although this does not necessarily imply that the electrical installation is unsafe).
Several associations and trade bodies allow the issuing of a Minor Works Certificate.
A minor works is defined as 'work which does not include the provision of a new circuit'.
Testing is still essential and a number of tests are specifically identified as essential to confirm safety.
Also included on the form is space to allow the inspector to comment on the existing installation.
In a practical sense, for most electrical contractors involved in installation testing, the most frustrating part of the job is the recording of test data onto test certificates.
Invariably, current working practices involve the printing out or copying of a certificate for all premises to be tested at the beginning of the working day.
As circuit testing is undertaken on site the electrician will then usually record details of the inspection with written information on the 'dummy' certificate.
At the end of the day, back in the office, the manually recorded results will then be transferred to an 'original' certificate for the customer.
When Must The Tests Be Carried Out ? IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
The International Standard IEC-603664-6 Provides Requirements for “ Initial Verification “ and “ Periodic Verification “
Of an Electrical Installation :
“ Initial Verification “ Consists of Visual Inspection & Testing , of an Electrical Installation to Determine , as far as Reasonably Practicable , whether the Requirements’ of the Other Parts of IEC-60364 have been Met , Including Requirements for the Reporting of the Testing Results ,
The Initial Verification takes Place Upon Completion of a New Installation or Completion of Additions or of Alterations to Existing Installations ,
Periodic Verification : Provides the Frequency and the Requirements’ for Periodic Verification of an Electrical Installation to Determine ,
As far as Reasonably Practicable , Whether the Installation and all its Constituent Equipments are in a Satisfactory Condition for Use ,
Including Requirements for the Reporting of the Testing Results , Chapter 7 of this Guide Reports some Consideration of Periodic Inspection ,
This Guide will Not-Consider Visual Inspections ( for example the Checking of the Method of Protection Against the Electric Shock like Barriers
And Distances , Colour and Size of the Conductors , Presence of the Diagrams , Appropriate Selection of Materials , etc . )
But will Focus on the Various Testing Regimes and the Stipulated Values which these Tests should Deliver ,
Requirements For Testing An Electrical Installation :
The Following Tests shall be Carried Out where Relevant and should Preferably be Made in the Following Sequence :
* Continuity of the Protective Conductors and of the Main and Supplementary Equipotential Bonding Conductors :
* Insulation Résistance of the Electrical Installation :
* Protection by SELV & PELV or by Electrical Separation :
* Insulation Résistance of Non-Conducting Floors and Walls :
* Verification of Conditions for Protection by Automatic Disconnection of the Supply -
( Fault Loop Impedance , Earth Résistance , RCD Tests )
* Polarity and Phase Sequence Tests :
* Functional and Operational Tests :
* Voltage Drop :
The International Standard IEC-60364-6 Requires that all Measuring Instruments and Monitoring Equipment Used for the above Tests Comply with the Series IEC/EN 61557 , if Other Testing Equipment is Used , it shall Provide the Same Degree of Performance and Safety as a Minimum ,
Electrical Systems : “ Experiment “
An Electrical System Consists of a Single Source of Electrical Energy and an Installation ,
Depending on the Relationship between the Source and the Exposed ( Conductive ) Part of the Installation to Earthing ,
The Standards define the Type of System as Follows :
TT , System : the Accessible Conductive Parts are Earthed Indepently of the Source Earth :
TT : L1 ─────────────── ------- ────────────────────
……. L2 ─────────────── ------- ────────────────────
……. L3 ── * ──────────── ------- ───*──────────────── ( Single Phase )
…….. N ── * ──────────── ------- ───*──────────────── ( PE ) – ( R ) – Earthing
Earthing Rod ,
IT – System : the Live Parts are Insulated from the Earth ( or Connected to Earth Through an Impedance Z )
The Accessible Conductive Parts are Earth Independently :
……………………………………. 3-Phase
IT : L1 … . ────────────────── -------- ────────────────
……. L2 … . ────────────────── -------────────────────
……. L3 … * ────────────────── ------- ──*────────── L3 - ( Single Phase
…….. N * ─↓──────────────── ------- ─────*─────── ( PE ) – R ( Earthing
.. ……………..... Z
Earthing
IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
Insulation Résistance of the Electrical Installation :
The Insulation Résistance shall be Measured between each Live Conductor and the Protective Conductor or Earth ,
In Locations Exposed to Fire Hazards , a Measurement of the Insulation Résistance between the Live Conductors’ shall be Taken
The Insulation Résistance , Measured with the Test Voltage Values Indicated in the Table below are Satisfactory if each Circuit , with the Appliances Disconnected , has an Insulation Résistance Not-Less than the Appropriate Value given in the same table ,
Nominal Circuit ………………………….. Test Voltage …………………………… Insulation Résistance
Voltage ………………………………………. d.c. ………………………………….
────────────────────────────────────────────────────────────────
SELV , PELV ………………………………… 250 v ……………………………………… ≥ 0.5MΩ
( ≤ 50 v a.c. ≤ 120 v d.c. )
────────────────────────────────────────────────────────────────
Up to & including 500 v ……………………… 500 v ……………………………………... ≥ 1 MΩ
( including FELV )
────────────────────────────────────────────────────────────────
Above 500 v …………………………………… 1000 v …………………………………….≥ 1 MΩ
────────────────────────────────────────────────────────────────
Typically for 230 / 400 v Circuits ( Excluding SELV & PELV ) IEC 60364-6 Requires that the Insulation Résistance at a Test
Voltage of 500 v d.c. shall be 1MΩ as a Minimum :
NOTE: Where Surge Protective Devices ( SPDs ) are Likely to Influence the Test or be Damaged ,
Such Equipment shall be Disconnected before Carrying Out the Insulation Résistance Test , Where it is Not Reasonably Practicable to Disconnect such Equipment ( e.g. in Case of Fixed Sockets-Outlets Incorporating an ( SPD ) the test Voltage for the Particular Circuit may be Reduced to 250 v d.c. , but the Insulation Résistance must have a Value of at Least 1MΩ
Protection by SELV , PELV or by Electrical Separation : 2392-10 / 2391-10
Even if the Automatic Disconnection of Supply by Circuits-Breakers , Fuses and RCDs , is Normally the most Common Protection Method . there are Other Protection Methods like Protection by SELV , PELV or be Electrical Separation or by Non-Conducting Floors and Walls ,
Only for these Cases shall the Separation of Live Parts from those of Other Circuits , be Confirmed by a Measurement of the Insulation Résistance , The Résistance Values Obtained must be in Accordance with table :
Below there is an Example of the Measured of Insulation Résistance to Confirm the Separation of Live Parts from those of Other Circuits :
Test Instrument : (1) One Lead On ( Between the Output of the Transformer ) 2-Wires
Test Instrument : (2) One Lead On ( And the Other Live-Parts – for SELV / PELV )
( And the Equipotential Bonding Rads ( SELV Only )
Insulation Résistance of Non-Conducting Floors and Walls :
When it is Necessary to Comply with the Requirements of the Protection by Non-Conducting Locations , the Floor and Wall Insulation Résistance / Impedance shall be Tested
In Part 6 of IEC 60364 Methods for Measuring the Insulation Résistance / Impedance of Floors and Walls are given as Example ,
IEC ←← Our Cousins Over the Seas Regulations’ 2392-10 / 2391-10
Verification of Conditions for Protection by Automatic Disconnection of the Supply :
Automatic Disconnection of the Supply is Required where a Risk of Harmful Pathophysiological Effects to a Person may arise due to a Fault as a Result of the Value and Duration of the Touch Voltage ,
The Verification of the Efficacy of the Measures for Protection against Indirect Contact by Automatic Disconnection of Supply is Treated below :
In Case of TN-systems :
According to the International Standard IEC 603664 , for TN- system the Characteristics of the Protective Device and the Circuit Impedance shall fulfil the following Requirements :
( Zs x Ia ≤ Uo )
Zs : is the Fault Loop Impedance in Ohms ,
Uo is the Nominal Voltage between Phase to Earth ( Typically 230 V AC for Single Phase & Three Phase Circuits ,
Ia is the Current Causing the Automatic Disconnection of the Protective Device within the Maximum Disconnecting Times Required by IEC 60364-41 that are :
- 400 ms for Final Circuits Not Exceeding 32A ( at 230 / 400V ac )
- 5s for Distribution Circuits and Circuits Over 32A ( at 230V / 400V ac )
The Compliance with the above rules shall be Verified by :
(1) Measurement of the Fault Loop Impedance ( Zs ) by Loop Tester :
(2) Verification of the Characteristics and / or the Effectiveness of the Associated Protective Device , This Verification shall be Made :
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