O.S.G.. The use of other methods’ of determining Maximum Demand is Not Precludedwhere Specified by the Installation Designer
FirstlyI make no Apologies for the Way am Writing on any Matters . it can be a first day Apprentice or some one Needing aJog of Memory . Sowe are all in the Same Boat . “ To Learn “
For the Apprentices . The Day we stop learning is the Day we hang Upour Tool-Bag
CookerDesign Current Calculations
Thefirst thing you have to do is get Your Head around the Calculations !!
(From a Design point of View ) 2392-10
DomesticInstallation Oven(s) & Hob(s) are to be Calculated upon their MAXIMUM LOADING Startwith a simple Calculation ( An Oven has a rating of 2kW ) 2000
(I = P/V ) Formula … I = 2000 ÷ 230V = 8.70A …. Weare Using the Unit Amps
-Controlled via a CookerSwitch with a Socket outlet .
Asa Designer . we’ll have to Apply Diversity ??
Important )- Diversity allowance to be Applied to the FULL LOAD CURRENT for CookingAppliances .
TheO.S.G. is telling us . Purpose of the Final Circuit fed from theConductors ) O.S.G.Table 1B p/97 – column (3) Cooking Appliances → At the Top of the Page Note : Type ofPremises ( 2392-10 → Household Installations ) Domestic Installation(s)
DomesticInstallation(s) Only O.S.G. - 10A + 30% f.l – Full Load ) of connected Cooking Appliances in the Excess of 10A+ 5A if a socket-outlet is incorporated in the Control Unit . ( C.C.U. ) – 45A + 13A Socket Switched with Neon .
Fromyour point of View ( The First 10A ofthe rated current plus 30% of the reminder ( Plus) 5A if the Control Unit incorporates s Socket.
Calculations)- You bank “ Hold OFF“ the first 10 Amps of the Maximum Load Current ) The10A will be used at the End of the Calculations’
-So your Work out the Total Power Rating & then calculate the Full Load Current
Calculations)- Power = ( 2 x 1 ) + ( 2 x 1.5 ) + ( 2+ 3 ) = 10kW
I= 10000 ÷ 230V = 43.48A … round it up to the first four numbers43.47826087 ( 48 ) 43.48A
-&-s . 2010 . Q ) Identify the Two Types of Test InstrumentIdentified in GN-3 . Which may be Usedto confirm “ Phase Sequencing “ GN-3 . 2.7.17. Phase – Sequence . p/54
i) Rotating disctype . ii) Indictor Lamp Type .
you have correctly Identify these InstrumentTypes . for -&-s
While the following tests are NOTa specific requirement of BS-7671 . it is recommended that they arecarried OUT.
In order to test the effectiveness of Residual CurrentDevices after installation . a ( Series of Tests ) may be applied to check thatthey are within specification & operate satisfactorily . ( Regulation - 612.8.1.) p/193 . & Operate satisfactorily . This test sequence will be in addition to providingthat the test button is operational . the effectiveness of the test buttonshould be checked after the test sequence .
2392-10 : foreach of the tests . Readingsshould be taken on ( Both Positive & Negative half-cycles & the longeroperating time recorded .0
411.4.5. . Prior to these RCD tests it isessential . for safety reasons . thatthe earth loop impedance is tested to check the requirements have been met .
TN-S . System . example.. 612.8.1. The ( Verification ) of the ( Effectiveness ) of the measure for faultprotection by automatic disconnection of supply is effected as follows .
1) measurement ofthe earth fault loop impedance – see Regulation . 612.9. 2) verification of the characteristics & / or theeffectiveness of the associated protective device . This verification shall bemade .
- for overcurrent protective devices . by visualinspection ( i.e. short-time or instantaneous tripping setting forcircuit-breakers . current rating & type for fuses . - RCDs . by Visual Inspection& Test . ◄◄◄ The effectiveness of automaticdisconnection of supply by RCDs shall be verified using ( Suitable Test Equipment ) according to ( BS-EN-61557-6 ) . see Regulation 612.1. To confirm that the relevant requirements in Chapter 41 are Met .
The disconnection times required by Chapter41 . shall be Verified .
Re: ***Cont../ Useful Information for Electricians’ & Apprentices***
hi im just starting my 2392 10, i have a question . IDENTIFY IN ORDER TO PRODUCE A DESIGN SPECIFICATION THE INFORMATION REQUIRED FROM THE (a) CLIENT
(b) electricity distrubution network operator (DNO)
COULD YOU GIVE US A PUSH IN THE RIGHT DIRECTION TA
HASAWA . 1974 – Statutorydocument ) EAWR . 1989 – Statutory document ) BS-7671:2008 / 2011 – Non Statutory document ) O.S.G. – Non Statutorydocument ) Guidance Note 3 – Non Statutory document ) GS-38 – Non Statutory document )
Electrical Installation Certificate . Certificate is used for ( NewInstallations ) whenever a New circuit has to be Installed . & /or Alternations . Rewiring & anycircuit where the protective device has been changed . As part of the (Initial Verification ) the date for the next Inspection must be set ( maximum 10 Years for Domestic Installation )
Certification & Reporting
This form must be Accompanied by ( Inspection Schedules& Test Results Schedules ) In the case of ( Consumer’s Unit change only ) Electrical Installation Certificate would be required for the ( Consumer’sUnit ) & an Electrical Installation Condition Report ( EICR ) should be completed for the ( ExistingInstallation )
Minor Electrical Installations Work Certificate . □ This one isUsed for work which ( Does ) not involve theInstallation of a ( New Circuit ) □ This Certificateis to be Used when ( Additions to Existing circuitsare carried out ) if . □ More than Onecircuit is added . Then a separate - Minor Works Certificate . must be issuedfor ( EachModification )
Your reasons . for this type of Test are . Wear & Tear . Change of Ownership . Change of Use . Damage to the Property.
Certification & Reporting This form must be Accompanied by ( InspectionSchedule & Test Results Schedule(s)
□ Diagrams .Charts or Tables should be made available to the person carrying out thisReport . These Diagrams .Charts or Tables should indicate : Type of circuits & Protective devices .means of Isolation & Switching . methods used for Protect against Fault Protection .
Delegate . will be required to complete the AppropriateDocument during & after the Testing is carried out . ( Starting from . 01.01.2011 . this Documentwill be the ElectricalInstallations ConditionReport . ( EICR )
2392-10 : Weneed to Inspect & Test Electrical Installations to ensure compliance withBS-7671 :2011 .( Non Statutory document ) 2392-10 : Bycomplying with BS-7671 :2011 . We arealso complying with HASAWA - 1974 & EAWR - 1989 Both ( Statutorydocument )
-&-s point of View 2392-10 . Insulation Résistance Measurement . (Measurement of Insulation Résistance are to be carried out before the first connection of Main Voltage to the Installation ) …D.C. test voltage .
2392-10 . Take from BS-7671:2011 . -&-s .
( T ) Which of thefollowing items should be ( Included ) forchecking during the ( Initial Verification ) of an Installation . Presence of diagrams & Instructions . ( Regulation –611.3. (xvi ) Presence of diagrams . instructions &similar information . p/190
Take from BS-7671:2011 . -&-s . ( T ) One ( Item ) that should be ( Included) on charts & diagrams made ( Available ) tothe person carrying out the ( Inspection & Test ) is . All Isolation & Switching arrangements ( Regulation – 514.9.1. ( iii ) p/117 .
Take from BS-7671:2011 . -&-s . ( T ) An ( Inspection ) shall be made to ( Verify) that the installed electrical equipment is . NotVisibly Damaged ( Regulation –611.2. ( iii ) p/189 . ( iii ) – Routing of cables in Safe zones . or protection againstmechanical damage . in compliance with Section 522
( T ) Inspection & Testing . Continuity of CPC & Protective Earthing . ( You will use this on .Periodic Inspection &Testing )
p/Regulation 411.3.1.1. of BS-7671:2011 requiresthat Installations which provide protection against Electric Shock using Automatic Disconnectionof supply must have a circuit protective conductor run to & terminated ateach point in the wiring & at each accessory .
Re: ***Cont../ Useful Information for Electricians’ & Apprentices***
Brianmdk. Thank you for using this Forum . “ As arule you go into the Main Forum Q/As “
“ Old Amber “ . only writes up things for the Forum . . I am sure that Phil or any other Memberwill pick this up . Has a rule I don’t. do Q/As . I leave that to the Professional Memberson this Forum . I will get in touch with Phil .
Brianmdk. am sure Phil has a ForumE/mail .
I get over 100 E/mail a day . So I limit my time when I can .
Example . -&-s . Correctly indentify the Three documents on which ( Ze) would be recorded .
This is how Ipicked up this . 2392-10 . Look in & start there . p/390 . EIC . ( Ze ) yeah . Minor / No . EICR / yeah . sometime we have to help ourselves .
2392-10 : Check – 530.3.4.which seems to require that the only protective devices specified by themanufacture can be used in a Consumer Unit .
Forinstallations with a 230V single-phase supply rated up to 100A that are underthe control of Ordinary Persons . Switchgear & Controlgear should ether :
-Comply with BS-EN-60439-3 & Regulation 432.1.of BS-7671:2011 .or -be a Consumer Unit incorporating components complying with BS-EN-60439-3 .
2392-10: Check – 537.1.4. Amain switch intended for operation by ordinary persons . e.g. of a household orsimilar installation . should interrupt both LiveConductors of a Single-phase supply .
531.2. RCD Requirements .– 531.2.1. An RCD shall be capable of disconnecting all ( Line Conductors ) at substantially the ( Same Time )
531.2.5. An RCD cannot be used for ( Fault Protection) on its Own . Where a circuit does “ NOT “ contain a ( Protective Conductor )
2392-10. Does an RCD . NEED an EARTH .
531.2.5. The use of an RCD associated with a circuitnormally expected to have a ( Protective Conductor ) shall NOT beconsidered sufficient for fault protection if there is ( NOsuch conductor ) even if the rated residual operating current ( IΔn ) of the device not exceed 30mA . … ►► RCD without ( Earth ) N/A
Taking off the Internet . ▼▼▼
RCDdoes NOT necessarily require an Earth connectionitself . ( it monitors only the Line& Neutral ) in addition it detects current flows to Earth even in equipmentwithout an Earth of it Own .
RCD- The amount of current flows through the Line should return through Neutral . RCD– it Trip the circuit when there is ( Earth Fault Current ) .. Now it takes us back to Regulation ( 531.2.5. ) DOWeNEED an Earth
RCD/ RCBO . “ Flying Lead “ has a Functional Earth
Often. there is great confusion over Earthing . Bonding ( Earth Bonding) BS-7671:2011 . requirements forElectrical Installations – “ Defines “
“Earthing “ Connection of the ( Exposed – Conductive – Parts ) of an Installation to the main earthingterminal of that Installation “ Bonding “ Thecorrect “ title“ is “ p/27 . EquipotentialBonding “ electrical connection maintaining various Equipotential Bonding & ( Exposed – Conductive – Parts ) & ( Extraneous – Conductive – Parts ) at substantiallythe same potential .
►►See also . “ Protective Equipotential Bonding “ p/32. “ Equipotential Bonding “ for the purposes of Safety
(Extraneous – Conductive – Parts ) a “Conductive Part “ . liable to introduce a ( Potential ) generally earth (Potential ) & not forming part of the electrical installation .
(Exposed – Conductive – Parts ) a “Conductive Part “ of equipment which can be touched & which is not a Livepart but which may become Live under fault conditions
Just a Reminder . 411.3.1.2. Protective Equipotential Bonding . Ineach installation ( Main Protective Bonding Conductor’s ) complying withChapter 54 . shall connect to the ( Main EarthingTerminal ) Extraneous – conductive - Parts . including . ( Water Installation pipes : Gas Installation pipes : Exposed Metallic Structural parts of theBuilding : e.g.
Requirementsof the Earthing System . Thefunction of the earthing system isTwo-Fold .
□ To provide a low enough impedance path . viathe earth conductors . back to the supply source so that the event of a failureto earth of a live conductor . sufficient current will flow safety along apredetermined route to enable the (Circuit Protective device to operate )
□ To limit the ( Potential rise ) on allMetalwork to which persons & livestock normally have access . To a safevalue under normal & abnormal circuit conditions . Thebonding together of all normally ( Exposed metalwork ) such . As Gas . Water . etc . & the connection of the ( Bond ) to the Earth Terminal . will prevent thepossibility of a ( Potential difference) arising between adjoining pipework under both normal & abnormalconditions .
Thereare Two main types of Earth Conductors . which are “ Bonding “ referred to as ( Protective ) conductor(s) & Earth Electrodes . p/23 . Bonding Conductor : A protective conductor providing EquipotentialBonding . Equipotential Bonding – Main Protective Bonding Conductor .
□The bonding together of all normally ( Exposed Metalwork ) such . As Gas . Water . etc . p/37 .Main Metallic Water Pipe – ( Extraneous – Conductive – Part - p/28 )
Bonding& Protective Conductors . Withinthe Regulations . a number of “ Definitions“ you have to describe the differenttypes of earth conductor used .
CircuitProtective Conductor ( CPC ) Thisis a separate conductor installed with each ( Circuit ) & is present toensure that some . or all . of the ( Earth Fault Current ) will flow back tosource along it . Itmay be an ( Individual ) conductor . the ( Metal Outer Sheath of a Cable ) or ( Metalwork formed by Conduit or Trunking )
Theseensure that ( Exposed – Conductive –Parts ) such as Metal Enclosures . remain at approximately the ( Same Potential) e.g. Under Fault Conditions . p/27 .Exposed – Conductive – Part . Conductive part of equipment which can betouched & which is not normally live . but which can become live . UnderFault Conditions . ►The two forms of “ Bonding Conductors“
p/37. • EquipotentialBonding is Main Protective Bonding Conductor . whichinterconnect ( Together ) & to Earth . ( Exposed – Conductive – Parts )which do NOT normally carry current . “ But “ could do so under a FaultCondition . these( bonds ) normally connect Exposed –Incoming Metal – Gas . & Water pipes……. Main Services . to the ( EarthingSystem )
asit was on the 16[SUP]th[/SUP] Edition . & is still in Use today . SupplementaryBonding Conductor(s)
Toensure that Electrical Equipment & other items of ( Conductive – Material )in specific ( Zones ) are bonded tighter & remain at ( Substantially the same Potential ) Theyare used in ( Addition to the Main Protective Bonding Conductor . & (Circuit Protective Conductor )
EarthElectrodes . designer . is faced withTwo – Tasks .
□ To ( Achieve ) a required Impedance Value . □ To ( Ensure ) that “ Touch Voltage “ potentials are satisfactory . 50V .
(TT System ) for most if NOT all of this “ Site “ You do this by NOTusing the DNO – Earth . you provide a ( Rod ) Therisk of Electric Shock is high . TN-C-Ssystems must not be used forConstruction & Demolition sites Supplies . TN-C-S supply is provided by the supply provider . ( PS .use your own judgment ) No in the regulations. it may be Converted to a ( TT System this is easily achieved by isolating the supply earth fromthe installation & installing an Earth Electrode for use with an RCD – 500mA
TestingEarth Electrode(s) . Pulled out oldNotes . So that got me Started . !! Books are Out .
Ifa 30mA RCD is used . this allows a maximum Electrode Résistance of ( 1.667Ω) although it is recommended that earth electrode résistance should never begreater than ( 200Ω ) A maximum valueof ( 100Ω) is proposed in a draft amendmentof BS-7430 . Code of practice forEarthing .
BS-7430:1991 – which is withdrawn . Guidanceon the Methods for Earthing Electrical Systems
“ Abstracts “ BSI … BS-7430: 1991 – which is withdrawn. Givesguidance on the methods that be adopted to ( Earth ) an Electrical System forthe purpose of ( ►► Limiting thePotential ) with respect to General Mass ofEarth . of current – carrying – conductors ( Forming part of the System) & ( Metalwork associated withEquipment . Apparatus . & Appliances connected to the System )
TheElectrical Supply . 16[SUP]th[/SUP] Edition Thefollowing electrical systems are NOT suitablefor use in hazardous locations . TN-C. TN-C-S. ( PME ) InTN-C & TN-C-S - ( PME ) supplies . the Neutral conductor is also the Earthingconductor . Therefore . there could be a ( PotentialDifference ) between the main earthing terminal of the Installation& the General mass of Earth .
This( Standard ) applies ( Only) to land – basedInstallations .
BS-7375:2010 . Distribution on Construction& Demolition Sites . Code of Practice .
Whatkinds of sites are covered by BS-7375 . BS- p/214.
Thesites covered in this standard are areas where any of the following take place. • Construction work of new buildings • Repair . alteration . extension . demolitionof existing buildings or part of existing buildings . • Engineering works . • Earthworks . • Work of similar nature . -This requirements apply to ( Fixed ) or ( Movable Installations )
Updatingof references to BS-7671 . take into account the publication of the seventeenthedition.
704.411.3.1. – Protective measure . Automaticdisconnection of supply . A( PME ) earthing facility shall NOT be used for the means of earthing for aninstallation falling within the scope of this section ( Unless ) all Extraneous – Conductive – Parts . are reliablyconnected to the main earthing terminal in accordance with Regulation – 411.3.1.2.
Justa Reminder . 411.3.1.2. Protective Equipotential Bonding . In each installation ( MainProtective Bonding Conductor’s ) complying with Chapter 54 . shall connect tothe ( Main Earthing Terminal ) Extraneous – conductive - Parts . including . ( WaterInstallation pipes : Gas Installationpipes : Exposed Metallic Structuralparts of the Building : e.g.
Thereare differences between BS-7375 & BS-7671 . to do with ( Disconnection Times ) Thereis a large Overlap with BS-7671 . section 704 . different approach in ( BS-7375 ) particularly on the ( 110 volt system) 55 voltsto Earth .
Note . if a ( PME ) Earthing facility is ( Considered) for Use . see also . p/280 - BS-7375:2010 . 704.0./ 704.411.3.1. – Note
(p/54 - Disconnection Times ) 411.3.2.3. in a (TN- system ) a disconnection time Not exceeding ( 5s ) ispermitted for a distribution circuit & for a circuit NOT covered by Regulation . 411.3.2.2. (p/54 - Disconnection Times ) 411.3.2.4. as Appropriate . in a (TT – System ) a disconnection time Not exceeding( 1s ) is permitted for a distribution circuit& for a circuit NOT covered by Regulation . 411.3.2.2.
( Disconnection Times ) for reduced – Low – voltage –systems in BS-7671 & see if you canfind any ( Equivalent in BS- 7375 )
Classificationof Tools . Class1 ) tool having at least ( Basic Insulation ) throughout & under certain conditionsrequired to be Earthed . BS-EN.61140. P/287 . Class11 ) tool with ( Double Insulation ) & / or reinforced insulation throughout& without provision for Earthing . BS-EN.61140.
Class111 ) tool designed for operatingat ( Safety Extra Low Voltage ) BS-EN.61140. Safety Extra Low Voltage ( SELV ) (- Nominal voltage not Exceeding 50Vbetween conductors . & between conductors & earth . No-load voltagenot ( Exceeding 50V )
704.410.3.10. Note 1 : The reduced low voltage system is strongly preferred forthe supply to portable hand lamps for general use portable hand tools &local lighting up ( 2kW ) Note 2 : The ( SELV ) system is ( Strongly) preferred forportablehand lamps in ( Confined ) or damp locations .
BS-EN- 60947-2 . MCCBs areadjustable – Thermal & Magnetic tripping characteristics . can be changedon the device . ( normally have to beObtained from the relevant Manufacturer )
RCDsmust conform to ( BS-4293 still on Old Sites )BS-EN- 61008 or 61009 .
Goeson to confirm that . in connection with Fault Protection . the application ofthe method of ( ProtectiveEquipotential Bonding ) is ONE of the important Principles for Safety .
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