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
2391-10)- Answer the Questions in full using correct terminology .
Example. Q / Which is the type of Inspection to be carried out on a New Installation . A / Initial Verification .
2392-10- Certification & Reporting . p/163 ( This is oneyou will get ) Simple – one Q/As 631.3– Where Minor Electrical Installation Work ( DOES -NOT-INCLUDE ◄◄ ) The provision of a ( NEW CIRCUIT) -) The hint is in there !! pleaseread
2391-10- Don’t git mixed up (- 633.1 . Additions & Alterations ElectricalInstallation Certificate or a – ( Minor Electrical Installation WorkCertificate . shall apply to all the Work of the Additions& Alterations -)
O.S.G.– 9A . 2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2[/SUP]has a résistance of ( 19.51mΩ) per metre .( 58 metres ) of cable will have a résistance of ? [5.8 x 19.51mΩ = 113.158 ] ÷ 1000 = 0.113]
Root meansquare ( r.m.s. )or effective value of a waveform ( Voltage &Current )
Apprentices. Test method 1 (- Uses the lineas a return lead . – Otherwise known as the ( R1 + R2 ) Thisis the most common method used for final circuits . Why ?
The Line conductor runs alongside a CPC conductor & this factor is Utilised in theTest . • Polarityof the circuit is also obtained at the same time .
- YouInitial checking for Continuity . -So Continuity testing & ( R1 + R2 ) readings . - (R1 + R2 ) on the Schedule of Test Results .
► Ifwe look at the O.S.G. . 9A . (- Somerows will have the résistance for ( R1 ) &some for just ( R2 ) & also for BOTH .
►2392-10.When using Test Instrument explain the importance of i) Verifying TestInstrument . ii) Regular Calibration . iii) Use of DocumentaryEvidence .
Asa Tester its your reasonably (- You must ensure that your Testing Equipment is Calibrated. Why ? This will indicates that the Instrument is working properly & providingaccurate reading . Downside to this . “ Question“ if you don’t do this . Your Test Results could be Void .
TheBasic Standard Covering the performance &Accuracy of Electrical Test Instruments is ( BS-EN61557 ) which incidentally alsorequires Compliance with the Safety Requirements of ( BS-EN 61010)
Asa Tester point of View . it should be compared with the . Ze + ( R1 + R2 ) Total & if it is ( Higher ) then further Investigation should be carriedout .
2392-10. every little bit helps towards 2391-10 . The measured value of . Ze + ( R1 + R2 ) will →[ NOT include Parallel Paths ] if carried OUT Correctly .
Parallel Paths . you will getenough on your 2391-10 . “ Very Important “
(R1 + R2 ) This value must be Entered for all circuit(s) unless it is notpossible to measure (R2 ) Where the measurement of ( R1 + R2) is not possible then the ( End to End ) Résistance of the CPCcan be measured using a Long Lead Method –Wander Lead
Apprentices(- RCD – setting on 30mA / be carful & do not mistake the TrippingCurrent for the current rating of the Device ) Just apoint . Yeah
Theone you will use a lot . BS-EN 60898 . MCB . ( YES ) / Table 41.3 – ( Zs) Theone you will use a lot . BS-EN 61009-1 RCBO . ( YES ) / Table 41.3 – ( Zs)
2392-10. you will get this on your Exams Principles’
Ifyou Double the Lengthof a Wire . you will Doublethe Résistance of the Wire . Ifyou Double the Cross-sectional-Area ofthe Wire you will cutits Résistance in HALF.
Becauseof Safety Reasons . AThick Earth Pin provides a ( Less Résistance )path for the Current to be Earthed.
ForSafety so the ( Leakage Current ) is any ( Will take the Less resistant Path ) to Earth pin. to Earth rather than a person operating the Appliance/ Equipment
Plusyour Ring Final Circuit . is a Continuous Ring - Earthing . sowhen you plug into a Socket . The rest speaks Volumes . Yeah
2392-10– you will hear this in Exams Principles’ . 3/5 day course .Cold Test / Testing .The cable has Not been Energized yet. Yeah . :aureola:
Doyou have ( Parallel Paths ) at this point . No .( A ↔ B ) Yeah .
Whenwe test the ( r1 to r1 ) we are doing a Cold Test . – Initial Verificationis a NewInstallation .
Firstly. you are Complying with BS-7671:2008 . ( Dual EarthTerminals )
Example. MK. Socket - Socket have two IndependentEarth Terminals . ( used for “ Clean Earth“ Installation )
Scenario . Keep in Mind you may have 12 Sockets on Ring Final Circuit. ?? Run off Cable ? 50m ↔ ( No Spur at this point )
Mypoint . Megger 1552 time . Set on Ohm’s. ? Zeroed my Test Leadsfirst . ◄
TwoLead(s) on Socket Earth bar = my Readingis 0.23Ω / 0.55Ω - Radical Reading(s) . CopperBar .
Keepthis in mind . This was not on Backbox . yet ( NoParallel Paths ◄ ) A ↔ B
Justa Point to Note Here .
3x 2.5mm[SUP]2 [/SUP] . ( Adding a Spur ?? )
3x 4.0mm[SUP]2 [/SUP] ( Radial ? ► 6 x 6.0mm[SUP]2 [/SUP] (Stranded . We use Stranded cable for Flexibly .) you will get this on CoP .
Example. if we use the principles off the Earth pinon a Plug . “ Bigger – Least Résistance . Bigger – Cable - Least Résistance Amreferring to the Socket . BS-1363 only here . ifwe look at the Earthing Bar – Bigger – if willhelp to clear an Earth Fault much Faster .Yeah
Parallel Paths (- through the Heating Pipes ( Combi boiler) Before you start saying . you didn’t need to Earththe Boiler . is the Main Water Pipe Earthed . Metal . Yes Dowe have ( Parallel Paths ) Cold Water feeds the ( Combiboiler )
Sockets. has Contact with the Backboxs . ( Parallel Paths ) . ?? - 20 x backboxes . 20 x Sockets
Seemto be another ( Parallel Path ) involved .
Scenario ?? i)First Fix . I test my ring ( if not cut ) . Cut . by connecting to a connector Block(s) [ r1 – r1 ] – [ n1 – n1 ] [ CPC – CPC ] you reading is True& Low . ( Continuity ) Scenario ?? ii)if I connect Ring to” just “ Socket(s) would my Reading go up . ?? in Ohm’s Scenario ?? iii)if I connect Ring to Socket(s) & Backboxes . ?? would my Readinggo up . ?? in Ohm’s
Sodo we have . ( Parallel Path ) … Parallel Path(s) takes many forms . Yeah
2392-10. Ifyou have Measured the ( Zs) then you do not need to ◄►Calculate it. :89:
Scheduleof Test Results . Certification & Reporting . – EarthLoop Impedance . ( 0.74Ω ?? ) Straight onto the Schedule of Test Results
“ DoCheck your Polarity “ ( if we look ◄◄ atSchedule of Test Results/ p341 ( Equipment Vulnerable to Testing - Confirmation ofSupply Polarity )
Scheduleof Test Results . ( PFC ) – Ze .at the Origin .
From. GN-3 – Two Fold . 2391-10 .
( Ze ) - i ) . Toverify that there is an Earth Connection . ( Live Test - Line & Earth ) with( Parallel Paths disconnected ) ii ) . To verify that the . ( Ze ). value is Equal to or Less than the valuedetermined by the Designer & used in the Design Calculation .
Remember : to Null your TestingLeads on your Tester . ( kA )
RingFinal Circuit . • Whatto look for (- there maybe a Dodgy Connection) Readingson Sockets • Measuredvalue of ( R1 + R2 ) could have a Spur . ( Higher value of ( R1 + R2 )
Part1 . Introduction . ThePurpose of these Regulation(s)
“ Circuit Conductor “ “Conductor “
“ Circuit Conductor “ means AnyConductor in a system which is intended to carry electric current in normal conditions . or to be Energised in Normal Conditions
“ Assessor“ Two-Fold Here.
Electricityat Work Regulation(s) 1989 . Requires proof that an ElectricalSystem is Safe .
Proper Inspection & Testingof a System by ( Competent People ) the rest I have left out . Etc
Includes(- Combined Neutral& Earth conductor(s)
2391-10(- Not Include a “ Conductor “ provided “ Solelyto Perform “ a ProtectiveFunction . to Earth . ◄◄ Hope this helps you along the Way .
Canthe . Line & Neutral& Earth . Become “ Live “ YES .
2392-10(- Certification & Reporting . ( Electrical Installation Certificate ) are we complying with Electricity at WorkRegulation(s) 1989 . PROOF. :89:
UsefulJunk .
:willy_nilly: 612.2.1. AContinuity Test shall be made . it is recommended that the Test be carried outwith a supply having a No-load voltage between( 4V & 24V d.c.or a.c. ) & a ShortCircuit Current of not less than ( 200mA ) ↔ ( 0.2A )
LowRésistance Ohm Meters Thiscan take the form of a specialised Low-ohm-meter or . Continuity range of anIR/Continuity tester .
Instrumentto BS-EN 61557-4
Measuringrange must cover a span of at least ( 0.2Ω to 2Ω ) Digitalresolution must be ( 0.01Ω )
Point to Note : Resistor in Parallel would bring down the Readings . Point to Note : Could we have a Trapped a Wire / when the Fittings are Screwed back . ? Point to Note : Do we have a Faulty Socket . ? Spur . ?
2392-10. ( Design Principles’ you may use One Day) ▼ PS. Not on Consumer Installation(s) – 2391-10 & further down the line .
►►Remember that 2392-10 (- p/48 . Table 41.3.For the Types & Ratingsof Overcurrent Devices listed [ May be Used instead of ►►Calculation] MCBs / RCBOs . Yeah
Firstly(- Other Methods are NOT precluded ◄ :41:
Appendix14 – p/361
Measurement of Earth Fault LoopImpedance . Consideration of theIncrease of the Résistance of Conductors with increase of Temperature . ETC
Therequirements ( 411.4.5. or 411.5.4 ) as appropriate . are considered to be met when the measured value of Earth Fault LoopImpedance ] Satisfies the following Equation
Zs (m) Measured Impedance of the Earth Fault Current Loop up to the most distant point of the relevant circuit fromthe Origin of the Installation . → ( Ω ) Uo . is the Nominal ( A.C. –r.m.s. ) Line Voltage to Earth ( V ) .. Symbols used in Regulations . p/35 Ia . isthe current causing the Automatic Operation ofthe Protective Device within the Time Stated in Table ( 41.1 ) Maximum DisconnectionTimes .
Scenario(- MCB – type B. ( p/249 – BS-EN 6089832A ) .. 32 ÷ 160A = ( Ia / 0.2 ) ↔ ( t )
Or . Within ( 5s ) According to the conditions stated in Regulation( 411.3.2.3. ( A )
i)– Line Conductor to ProtectiveConductor Loop Impedance of the Supply is First Measuredat the Origin of the Installation . ( L / E ) “ Live Test “ ii)– The Résistance of the Line Conductor & Protective Conductor of the Distribution/Circuit(s) areMeasured . [ ExternalLoop Impedance ] iii)– The Résistance of the Line Conductor & Protective Conductor of the FinalCircuit are Measured . iv)– The values of Résistance measured in Accordance with ( ii ) & (iii ) areIncreased on the basis of the Increaseof conductor Temperature . Taking into considerationthe ( Design Current – Ib ) v)– The values of Résistance increased in Accordance with ( iv) are Finally Addedto the value measured at ( i ) to obtain a realistic value of ( Zs ) Under Earth FaultConditions .
Remember that 2392-10 (- Formula . Calculating – Earth Loop Impedance. - Zs = Ze + ( R1 + R2 ) – for Apprentices Internal/ External - ( R1 + R2) Simple . Yeah
Foodfor Through – Regulation 433.1.5. ( Wording ) Can generally be Achieved by it / Doesnot say it is Achieved BY ?? :34:
Scenario(- 2392-10 .
( Ib ) in each Leg of cable is not to be Exceed ( 20A ) Current will not bethe Same All Around ( Ring FinalCircuit )
Assumedto be ( 20A ) at far End ( Additional / 12A ) Evenly Distributed. ◄◄◄
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