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
1)Select a ( GS-38 ) ApprovedTest Lamp or Voltage Indicator . 2)Check ( Test /Lamp / Voltage ) indicatoris functioning correctly by testing on a ( Known Supplyor Proving Unit ) 3)Determine whether Isolation is for ( Whole Installation or ( Specific Circuit(s) . 4)Locate means of Isolation ensuring there is no ( Standby Supply Arrangement ) 5)Switch ( OFF& Lock OFF Isolation device(s)e.g. Fuses Switch . Isolator . MCB . 6)Verify . ( Using Test Lamp / Voltage Indicator. Circuit(s) are Dead between Line(s) Neutral & Earth. 7)Erect ( Warning Notice(s). in appropriate position(s) . 2392-10 . atConsumer Unit . 8)Re-check ( Test Lamps / VoltageIndicator ) is still functioning correctly . 9)Retain Key(s) . for Locking OFF Devices /
b) Before carrying out InsulationRésistance Testing it must beestablished that there is ( No Voltage Sensitive Equipment Connected ) thatmay be damaged or Malfunction because of the test voltage applied .
TheEquipment would either have to be disconnected during test . ( Testing / 612.3.3 ) ……….. PLUS – Note . Wherethe circuit includes ElectronicDevices .
OrInsulation Test with Line(s) & Neutral connected together & Test between theses& the Protective Conductor .
c)Before carrying out Insulation Résistance Testing it must also be established that there is ( No Electronic Components ) that may be damaged ormalfunction because of the Test Voltage Applied .
Example - Dimmer Switch . This would have to beRemoved during test & the switch wires connected together .
- Describe Methods of Testing Insulation Résistance :
Beforecarrying out Insulation Résistance Testing ensure that . ??
1)All lamps . capacitors & loads are disconnected . 2)Voltage sensitive electronic equipment such ad Dimmer Switches . Touch Switches. Delay Timers . Power Controllers . Fluorescent lamps starter . Emergency Lighting . RCDs are disconnected . 3)There is No Electrical Connections between Line(s) . Neutral &Earth .
2392-10 : RCD . the contacts will Automatically be Opened . Thereby providingagainst Electric Shock . The Term . “ RESIDUAL “ in Residual Current Device implies that ( There) is a residual current flowing in the ( Circuit )Over & above that required to provide ( Power to aLoad ) :yesnod:
2391-10 : ( This maybe helpful in Exams ) WORDING . Yeah :6:
612.2.1. Continuity ofProtective Conductors :
Protective Conductors .
Describethe need for . & Methods of . verifying the ( Continuity) of Protective Conductors & the “ Interpretation of results. ◄◄ :willy_nilly:
“ Answer “
TheContinuity of the ProtectiveConductor is very important since it ( Forms Part) of the Earth Fault Loop Path . Inthe event of a Fault to Earth the Faultcurrent flows through the Protective Conductors& the Earth Fault Loop Path as a whole . Ifthe impedance of the Path was too high the Fault current may not be largeenough to operate the Protective Device thusresulting in ( Exposed Metalwork becoming Live )due to the circulating Fault current .
SELV ( Howdo I know / p/31 – Regulations . ) Extra – Low .
Describe the Test to Verify Separation between ( SELV ) circuits & other circuits ( -&-s )
SeparatedExtra Low Voltage ( SELV ) circuits operated at voltages up ( 50V ) or ( 120V d.c. ) This voltage can be obtainedin a number of ways such as a ( Double / Wound Transformer ) having a supply primary coil connected tothe 230V a.c. . Supply & an outputsecondary coil at the required Extra Low Voltage . Thetwo coils are not & should not be connected in a ANY way 7 a test must be carried out to prove this .
Byusing an Insulation Resistance Tester . set to ( 250Vd.c. ) test voltage on the ( MΩ ) rangecarry out the following test procedure . With the transformer disconnected fromthe supply connected one test lead to the Primary coil & the Other testlead to the secondary coil .
Pressthe test button & note the reading in ( MΩ ) .
Tocomply with BS-7671:2008 . This reading should be no less than ( 0.5MΩ )
Whatis the definition of Inspection . Inspectionis a general term that can have a wide variety of meaning . Will usually bemore specific / VisualInspection or Non-destructive Testing .
GN-3p/63 . ( PIR ) 621.2. Theformal Inspections should be carried out in accordance with Chapter 62 ofBS-7671 . This requires an Inspection comprising careful scrutiny of the Installation. carried out without Dismantling or Partial Dismantling as required .together with theAppropriate Tests of Chapter 61 .
EarthFault Loop Impedance . TheImpedance of the Earth Fault Loop . Line - to - Earth Loop . Starting& Ending at the point of Earth Fault .
RingFinal Circuit . Final Circuit arranged in the form of a Ring & connectedto a Single Point of Supply .
ResidualCurrent Device . ( RCD )
( Residual / Dual . meaning two . Line& Neutral – Two liveconductors .
ItUses the Idea that the Current in the Line &Neutral must be Exactly the Same . Yeah ( Balanced )
TheRCD does is compare the Current in the Line& Neural . If they’re not Identicalit Trips Out .
Regulationsinitially call for Visual Inspection . but someItems such as Correct Connection of Conductors . Canbe done during the actual Testing . :coolgleamA:
O.S.G.p/86 612.7. EarthElectrode Résistance . ( Ra ) - 200Ω
612.7. : Electrode underTest is being used in conjunction with an ( RCD)
A Loop Impedance Tester ( Zs )
TTSystem(s) . The value of the Earth Electrode Résistance ( Ra ) in Ohms. Multiplied bythe Operating Current in Amperes of the Protective Device . ( I∆n ) should NOTexceed ( 50V ) ( Ra ) = 200Ω . Then the maximum RCD operating Current should NOTexceed ( 250mA ) :coolgleamA:
ASimple Résistance test between the Ends of the Line . Neutral or Circuit Protective conductors willonly Indicate that a Circuit Exits .
Whetherthere are Interconnections or Not .
Same value whatever diameter is measured .
(L1 / N2 ) ↔ ( N1 / L2) Circuit formed by Cross- connection .
InitialVerification : Aftercross connection of Line & CPC you’d check between Line & CPC at every Socket & Spurs would becomeApparent . ( Spur ) will give a Higher Reading .Ω
Apprentices: ( Firstly – You Reading confirms thatthere is No Open Circuit on the Ring Final Circuit) Yeah .
RingFinal Circuit . ( Dead Test )
Instrument: Set on Ohm’s .
Under(- Schedule ofTest Results . CircuitLoop Impedance Ω RingFinal Circuit / Only measured – ( End to End )
Line/ Line - Little ( r1 ) = 0.43Ω . Measured – ( Endto End ) Bigger Copper / Lower Résistance . Neutral/ Neutral - Little ( r/n ) = 0.42Ω . Measured – ( Endto End ) Bigger Copper / Lower Résistance .
CPC/ CPC - Little ( r2 ) = 0.73Ω . Measured – ( End to End ) SmallerCSA / High Résistance
Topquark. I can’t Editany Post . on my Section(s) Thankyou . :coolgleamA:
Polarityis towards the end of the recommended test sequence . 612.6 :svengo:
Polarityon the Ring Final Circuit conductors is Achievedsimply by conducting the Ring Circuit Test .
Asfor Radial socket outlets . (- Continuity of the CPC will have already been Proved by linking Line& CPC & Measuring between the same terminalsat each socket . OnlyLine / CPC reversalsneed to be Checked .
612.2.Continuity of Conductors . We are conducting this Test at the same time as thatfor Continuity of CPCs . ( In Theory ) :bulb2:
Wedo this for Ring Final Circuit . CPCs End – End Wedo this for Radial . Line / CPC
( In Theory ) Radial Circuit . Line / CPC . we are using Wander Lead Return .
Linkingtogether Line & Neutralat the Origin & Testing between the same Terminals at “ Each Socket “ Line / CPC reversalwill result in NO Reading at the Socket inQuestion .
Lighting Polarity (- Link at Consumer Unit ) Line & CPC – Pendent Set . ( Polarity / proved by Operating Switch ) Switch wire / CPC . Switchis Opened & to confirm then Closed Polarity
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