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
“ Overcurrent ” a current flow in a circuit which is ( Greater ) than the ( Rated )current carrying capacity of the cables . :89:
Thiswould normally be due to a Fault on the Circuitor Incorrect Cable .
Ifa ( 20A ) cable protected by a ( 32A ) MCB was loaded by ( 25A) the cable would Overheat & the Device would continue to allow current to flow – This couldDamage the cable . ( Iz)
A Fault Current is a current which is flowing in acircuit due to a Fault ??
A Nail is driven through a cable causing an Earth Fault or a Short-CircuitFault . Thiswould cause a ( Very High Current to Flow ) through the circuit . Which must be( Interrupted ) before the Conductor reach a Temperature that could Damagethe Insulation or even the Conductor(s) .
FinalCircuits that are rated UP to & ( 32A ) require a maximum disconnection time of ( 0.2sec) 41.1. Distributioncircuit require a maximum disconnection time of ( 1 second ) 411.3.2.4
Ihave not done any TT Systems yet . Am working onit . Amber . ( Youwill get this on 2392-10 ) thisis a start . Yeah :coolgleamA:
ElectricShock : ( Earthing comes into Exams a Lot )
Two– Ways in which we can be a risk .
i)Touching Live parts of equipment or system that are intended to be Live . ii)Touching ( Conductive-parts) which are not meant to be Live . but havebecome Live due to a Fault . ( Basic Insulation Fails )
( Conductive-parts ) associatedwith the second of these can either be ( Metalwork )of Electrical Equipment & Accessories ( Class 1) & that of electrical wiring systems such as ( MetallicConduit ) & ( Trunking ) etc called (Exposed-Conductive-Parts )
orother ( Metalwork ) such as ( Pipes ) ( Radiators) ( Girders ) called ( Extraneous-Conductive-Parts )
17[SUP]TH[/SUP]Edition - P/24 ( Extraneous-Conductive-Parts ) A ( Conductive-part) liable to introduce a potential . generally Earth Potential. & not Forming part of the ElectricalInstallation
( Extraneous-Conductive-Parts ) NOT ( Forming part of the Electrical Installation )
17[SUP]TH[/SUP]Edition – p/21 ( Class 1 ) Equipment in which protection againstElectric Shock does NOT rely on Basic Insulation Only .
Butwhich includes means for the ( Connection of Exposed-Conductive-Parts ) to a ( ProtectiveConductor ) in the Fixed Wiring of the Installation . BS-EN 61140) :28:
BS-EN 61140 ) Protection against Electric Shock . :28: Commonaspects for Installation & Equipment requires That :-
• (Hazardous-Live-Parts ). Shall not beAccessible . • (Accessible-Conductive-Parts) Shall not be Hazardous-Live when there is ( No Fault or Under – Single FaultConditions )
BS-EN 61140 ) States that those ( ProtectiveMeasures ) providing protection under normal conditions ( That is . When no Faults Exits) provide Basic Protection & those ( Protective Measures ) giving protection Under Single Fault Conditions provide Fault protection– Sec 410 . refers
Themeasures of protection by ( Automatic Disconnection of Supply)
Regulations/ 410.3.3. - DoubleInsulation . - ReinforcedInsulation . -Electrical Separation to Supply to Supply a Single Item of Equipment . -Extra-Low-Voltage :- SELV . or . PELV . are generally applicable
2392-10. ( Automatic Disconnectionof Supply ) is the MostCommonly Employed method for Electrical Installation(s) .
TheWhys . - Double & ReinforcedInsulation are more frequently encountered in ( Items) - Electrical Separation . SELV/ PELV . are only Applied to ( Specific Parts of an Installation)
- Basic/ Protection . ( Protective Earthing ) - Barriers. ( Main Protective Bonding Conductor ) - Enclosures. ( Automatic Disconnectionof Supply ) in the Eventof a Fault . - Obstacles. ( Automatic Disconnectionof Supply ) for the PrimaryCircuit & connection of ( Exposed-Conductive-Parts ) ofthe Secondary Circuit connected to the ( Protective Conductor ) of the Primary-Circuit ofthe Source .
Point to NOTE : Fictional Extra Low Voltage ( FELV ) ◄◄◄ Equipment so supplied to ( TheProtective Conductor ) -&-s
WhereFictional Extra Low Voltage ( is Employed ) itis necessary to connect the ( Exposed-Conductive-Parts ) ofthe Equipment so supplied to ( The Protective Conductor ) of the Primary Circuit of the Sourcein addition to these Protective Measures required for ( ADS ) Regulation 411.7.3.
Whena Designer ( 2391-10) is considering the Use of ( Obstacles or Placing Out of Reach ) to provide Basic / Protection. it is strongly recommended that careful consideration be given to the ( Statutory Requirements ) relating to :-
• System. work activities & work equipment ( Regulation / 4. of the Electricity at Work Regulation 1989 ) •Insulation . Protection & Placing of Conductors ( Regulation / 7 . of the Electricity at Work Regulation 1989 ) •Work On or Near LiveConductors. ( Regulation / 14 . of the Electricity at WorkRegulation 1989 ) • Earthing . or other suitable precautions . (Regulation / 8 . of the Electricity at Work Regulation1989 ) •Working Space . Access & Lighting . ( Regulation / 15. of the Electricity at Work Regulation 1989 ) •Person to be “ Competent “ to prevent Danger& Injury . ( Regulation / 16 . of the Electricity at Work Regulation 1989 )
►►► Wording /NOT Act . ◄► But . Law . Exams ( Electricity at Work Regulation 1989 )
( Electricityat Work Regulation 1989 ) is ( law ) in the United Kingdom. ◄◄◄ in Exams / Wording is ( LAW )
ConsumerProtection is an ACT ◄◄◄ :75:
( Electricityat Work Regulation 1989 ) Applies to all ElectricalSystems at ( All Voltages )
2391-10- Inspection & Testing: ( Remember two different Words ) Yeah. 2392-10
Inthe case of most Types Electrical Installation there is ( No Statutory Requirement ) to carry out ( Inspection & TestingPeriodically )
Itis . However . A Commonly adopted practice seen as a Means of Meeting the Maintenance“ Obligations “
The. Electricity at Work Regulations 1998. Regulation ( 4 ) & the Housing Act 1985 –Section 11 . BS-7671 is in the Most Part concerned with the Design .Installation . & Initial Inspection & Testing of New Installations
Chapter62 . Containsa number of Requirements relating to ( Periodic Inspection & Testing ) . Regulation. 622.2. States that ( PeriodicInspection & Testing ) is not required an Effective Management SystemOperated by ( Skilled Persons ) covering itsMaintenance .
However. & as has been Mentioned Previously . ( The Person Responsibly may be Held Accountable in the Event ofan Incident Occurring )
(2391-10 ) Appropriate Records must be Keep of the Maintenance ActivitiesUndertaken . ( Cover ones But . Yeah ) :75:
ImportTerms . that -&-s . will bring up in Exams .
Statutory& Non- Statutory Regulations . Electrical Systems . TheBuilding Regulations ( Part P ) Instruments .
2392-10. Firstly . Foryour Assessor ?? are you aware of the Statutory& Non- Statutory Regulations that are relevant to InstallationWork
Tester. Example . Insulation Résistance. i)The Range of Instrumentrequired . ≥ 0.5MΩ / 0.1MΩ . ii)The Requirements regarding the Use & Performance of Test Equipment .
The more you put in the Easier it Becomes . :icon6:
Thestatutory regulations the apply to ( Electrical Work) 2392-10 / Initial Verification / NEW INSTALLATIONS . only
Let’skeep the Assessor . Happy . Yeah
TheHeath & Safety at Work . ( ACT ) ◄ TheElectricity at Work Regulation 1989 . ( Law )
2392-10. The Building Regulation Part / P . ( Domestic Installation ) Yeah (This will guide you back to BS-7671 ) onMatters
BS-7671:2008/ British Standards . Non- Statutory Regulations. ( By using BS-7671 . You are complying with :- ( 2) TheHeath & Safety at Work . 1974 ( ACT ) TheElectricity at Work Regulation 1989 . ( Law )
2392-10. ( As an Inspector )-&-swill use the wording ( Inspector / You ) → → → → Not ( Tester ) Fail :grouphug:
AnOvercurrent resulting from a ( Fault ) of ( Negligible Impedance ) between a Line Conductor & an ( Exposed-Conductive-Part ) or a ( ProtectiveConductor )
2392-10(- Protective Conductor Current ) “ Meaning “ ( Earth Leakage Current) Deleted / BS-7671:2008 ◄◄ :33: Acurrent which flows to Earth . or ( Extraneous-Conductive-Parts ) in a circuit which is ( Electrically Sound )
Thiscurrent may have a ( Capacitive Component )including that resulting from the ( Deliberateuse of Capacitors )
17[SUP]th[/SUP]Edition . p/27 . ( Protective Conductor Current ) Electric current appearingin a ( ProtectiveConductor ) . Such as ( Leakage Current )or Electric current resulting from an ( InsulationFault . ) :19:
Tocomply with the Electricity at Work 1989 . & BS-7671:2008.
It is necessary . in appropriate circumstances . Toprovide means to “ Provide “ means to “ Prevent “ any equipment from being Inadvertently or unintentionallyEnergized .
Safe Isolation . ( Padlocking in the Isolated Position )
BS-7671:2008. No VoltageLimitations are Specified . Yeah :19: Electricityat Work 1989 / Reinforces this ( Regulations apply to all System )
BS-7671:2008. 2392-10 – These are Designed toEncourage Good Practice . Yeah .
Ihave Knocked something Up . in wording .to help you along the Way . Amber . :thinking2:
Thefollowing Test results . States what tests have been performed & which meter has been used .
( Ω) • Low-résistance ohmmeter / Continuitytester . (MΩ ) • An Insulation résistance tester . ( Ω) • A Loop impedance tester . (mA ) • A residual current device ( RCD ) tester …….. -&s / GN-3. ( Test instrument should not beoperated for longer than ( 2 seconds ) (kA ) • A prospective fault current ( PFC ) tester . ( Ω) • An earth electrode résistance tester .
• An approved test Lamp orvoltage indicator ……. GS-38 • A Proving Unit …….. ( Thisis an Optional item of Test equipment )
• Insulation Résistance test isthe correct term for this form of testing .
• Loop Impedance tester . Thisinstrument functions by creating . in effect . an “ EarthFault “ for a brief moment . & is connected to the circuit via a Plug or by “ Flying Leads“ connected separately to Line . Neutral . & Earth. ( The instrument should only allow an Earth Fault to exist for a maximum of ( 40mS ) &resolution of ( 0.01Ω ) is adequate for circuitsup to ( 50A )
• PFC tester . Normallyone half of a dual loop Impedance ( PFC ) tester . This instrument measures the prospective ( Line – Neutral FaultCurrent ) atthe point of measurement using the same leads as for ( LoopImpedance )
Shouldbe Banned (- “ NeonScrewdriver “ which encourages the passage of Current . at Low-voltage .Through the body .
Proving Unit :
Thisis an Optional item of Test equipment . in thatTest Lamps should be proved on a known Live Supplywhich could . of course be an “ Socket Outlet/ Lighting Point )
TestLamp on such A Known Live Supply may involve entry into “ Encloses “ with the AssociatedHazards
-&-s. Point to Note . TestLamps must be Proved against a ( Voltage Similar ) to that to be Tested . ( 230V.≈ . Lamp ) ??????
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BS-7671:2008
