***Cont../ Useful Information for Electricians & Apprentices***

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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


2392-10/ Domestic Installation Oven(s)

Ovenhas 4 Rings ( 2 x 1kW ) & ( 2 x 1.5kW ) & Grill ( 2kW ) & Oven (3kW )

-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

UsingDiversity allowance stated ↑↑ ( 43.48A sub 10A = 33.48A )

I= 33.48 x 30 ÷ 100 = 10.04A

Youradding the ( 5A ) for Socket outlet . I = 10A + 10.04 + 5A = 25.04A )- Asa Designer this is your Expected Current Demand .

Remember )- Supply Cables Rated to suit DesignCurrent ( Iz )

 

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UsefulJunk :

IP56Protection .
Eachdigit in an ( IP ) Ingress Protection rating denotes résistance to Dust &Water . IP56 rating breakdown as follows .

IP- Ingress Protection
(5 ) Dustproof to sawdust . Dust & other Small Partials .
(6 ) Waterproof to Strong Jets of water .from any Direction .
Gardens. Workplaces / Shops . Industry . Farm buildings . Swimming pools . Squash courts . Gyms . ETC

IP- Ingress Protection
IP66. Offers total Dust Ingress Protection . & is protected againstHigh-Pressure Jets from any Direction .

 

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UsefulJunk bulbs

whydoes light bulbs blow ?
Whydoes the Circuit Breaker trip ?

TheCircuit Breaker does not trip because a broken filament has dropped onto a leadout wire as some people would have you believe but is due to the gas orfilament in the lamp becoming Ionised . The hightemperature & large electric field can cause the gas to go into a CONDUTIVE STATE & the plasma will spread until it SHORTS OUT the lead wires

 

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Useful Junk “ Wording “ The Humble light switch .

“ Gang“
Means there are more than One Switch on a singlefitting .
“ Way“
Means that the switches will operate from two or morelocations . i.e.

•What isthe current rating of a Switch ? The maximum Currenta Switch is designed to Carry !
•What isthe Voltage rating of a switch ? The maximumVoltage allowable in the circuit in which the switch is installed . 230V

 

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Testing - ►► A common trick question in any ExamPaper(s) 2391-10 / 2392-10 -&-s

►►►►► ( Making you aware - The x5 test is ( N/A )for Anything BIGGER than ( 30mA ) RCD / ADS ☜
Testcurrent at )- 5 I∆n . The maximum testtime not be longer than )- 40mS “ Answer“ Device shouldoperate in less than 40mS

( 500 is x5 ) I will give it its full title )- x5 I∆n ≤ 30mA Deviceshould operate in less than 40mS -&-sOut of this . there three Questions in here

 

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The point of all this is ( ThisForum will help you as much as possible 99.9% ) We all Love -&-s . Yeah

2392-10Question ?? -&-s

Asa Competent Person ) Tester to be .-&-s are judging you on this matter .

Amusing the Wording ( Testing – full stop )

ARCD must be Tested . ( No excuses )The Regulations are telling us . Therequirement(s) are stated in thefollowing Regulation ??? Where !!

TheEffectiveness of the RCD must be Verified by a TEST SIMULATING an APPROPRATEFAULT CONDITION ) – Full stop “ Push the Button “ ◄◄

Regulation 612.13 )- Functional Testing ◄◄


► Do not Mix up the two Regulation(s) 612.13 )- 612.10 ) ← ← ← ← ← ← ← ← ← ← ← ← ← ← ←


(Megger 1552 – out at this stage ) Regulation 612.10– Wording on this matter is.

( Visual Inspection is the First line of Defence ) Eyes

AdditionalProtection ( ADS ) The Verification of the Effectiveness of the measuresapplied for Additional Protection is Fulfilled by VISUALINSPECTION & TEST

RCDs shall be VERIFIED using SUITABLE TESTEQUIPMENT According to BS-EN 61557-6 …… ( Megger 1552 – out at this stage )
Thiswill take you to Regulation 612.1 . p/157
MeasuringInstruments & Monitoring Equipment & Methods shall be chosen inAccordance with the relevant parts of BS-EN 61557.

Youwill be Complying with Chapter 41 ( will be met )
Chapter41 – Protection against Electric Shock (Plain English is the RCD working to BritishStandard ? is it Safe . The Manufacture say there have tested it – all you doing covering you But . the other way of looking at this is “ The public will be Safe “

I don’twant to Harp on .

Remember“ RCDs – BS – 200mS -&-s ………………….. Still in Use
Remember“ RCDs – BS - EN 300mS -&-s

 

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TestInstrument :

Whatthe Regulation(s) are saying – The Test instrument used to Test RCDs should becapable of applying the FULL RANGE of TEST CURRENT ( BS-EN 61557 )

-&-s Question ?? The Test Current should be APPLIED for NO longerthan ( 2 seconds ) Your Answer

Must dash of to the Wholesalers now . Amber

 

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Justa point to Note here : RCDs Range of Tests

Whilethe following Tests are NOT a Specific requirement of BS-7671:2008 . it is recommended that they are carried out

Regulation(s)Table 61. p/158

( IR ) Insulation Résistance

≥ 0.5MΩ for SELV & PELV with D.C. you Test voltage of 250V -&-s 100%
≥ 1.0MΩ for systems up to & including 500V with a D.C. testvoltage of 500V &-s 100%

Workingmy why around the Regulations .

i)– RCD Table . performance criteria for RCDs to BS-EN 61008-1 & BS-EN 61009-1

Regulations:
Table3A . p/243

RCDswhich are identified in Two Main groups or Types of Delay .

Without time delay ( Classedas General Use )
With time delay ( Classed asType S for selectivity )

A 300mA RCD – is Only intended for Equipment & Fireprotection . -&-s ( Fireprotection )

Table( 12A ) P/358
ForDesign purposes )- “ Informative “ wecan class this as . Voltage Drop Table (Maximum 3% Lighting / Maximum 5% forother uses when the circuit is supplied from a public Low Voltage DistributionSystem

Calculations)- 3% of 230V = 6.9V ….. 3x 230V ÷ 100 = 6.9V
Calculations)- 5% of 230V = 11.5V ….. 5 x 230V ÷ 100 = 11.5V

If-&-s was to ask you a Question )- What is the Maximum Volt drop on aLighting Circuit ?? 5%

Apprentices. Designer(s) in the Making

Table41.1 - what the Regulations are sayingis )- Maximum Disconnection Time . 2392-10
TN- ( 120V < Uo ≤ 230V ) 0.4 seconds
TT-( 120V < Uo ≤ 230V ) 0.2 seconds ( PS now the catch .411.3.2.2. – Final Circuits’ NOTEXCEEDING 32A ◄◄◄ -&-s . this willgo around
( Final Circuit . is different from Ring Final Circuit (s) still NOTEXCEEDING 32A ◄◄◄ Watch their Wording .

Example)- Maximum Disconnection Times . Permittedby the 17[SUP]th[/SUP] Edition – for A.C. circuits’ of ( Nominal Voltage (Uo) 230V to Earth .
( 0.2s ) ( 0.4s ) ( 1s ) & ( 5s ) → ( 0.4 s being the most common inTN- systems – 0.2s in TT )

Apprentices – Regulations p/35 Symbols used in the Regulations ( Uo – Nominal a.c. rms Voltage to Earth . ( V ) … 41.1 . MaximumDisconnection times .

Designing.
41.2 to 41.5 )- Values for Maximum Earth Fault Loop Impedance ( Zs )
Designing.
41.5)- Providing Maximum Earth Fault Loop Impedance ( Zs ) values for RCD
Designing.
p/103- 52.1 )- Providing maximum operating temperaturesfor type of cable Insulation .
Thermoplastic / 70°C ) Temperature limit ↔ Thermosetting / 90°C ) Temperature limit
90°C) Temperature limit ( b)
Wherea conductor operates at a temperature exceeding 70°C it shall be ascertainedthat the equipment connected to the conductor is suitable for the resulting temperatureat the connection .
Designing.
p/104– 52.2 )- Cable surrounded by Thermal Insulation . O.S.G. P/125 Table 6B
Testing purposes . p/117 – 53.2
Guidanceon the selection of protective ( Isolation & Switching Devices )

BS-EN 61009-1 .. General RCD
BS-EN 61008-1 .. General RCD

BS-EN 61008-1 ( RCCBs ) General
BS-EN 61009-1 ( RCBOs ) General

BS-4293 ( RCCBs ) General
BS-7288 ( SRCDs ) General

BS-EN 61008-1 ( RCCBs ) Delay ( S )
BS-EN 61009-1 ( RCBOs ) Delay ( S )
BS-4293 ( RCCBs ) Delay ( S )

RCD)- 0.5I∆n Test should also be carried out ( Tocheck for Unwanted Tripping )

 

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Apprentices. “ Reasons “

AdditionalProtection . the 17[SUP]th[/SUP] Edition make a good point here ?? ( ADS ) using there Words Additional Protection Ring Final Circuit 30mA = 40mS

Inthe UK they Sell Electrical Equipment ( ghd – HairTongs £ 100 pounds plus ) Theseconversion plugs enable ( 2 – pin ) Europlugs to be connected to a standard UK 13A Socket outlet . inthe UKthey do not have a Fuse in the conversion plugs ( so there relaying on ( ADS )

Made in China – 50 / 60 Hz - 150W
Your Mans an Electrician (this is the second pair of ghd – my good ladyhas came home with the cable insulation has melted away in the middle of thecable ) Yes I can fix them ! right in the bin

 

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2392-10/ Leaning Curve .

Regulation536.2. Selectivity between Overcurrent Protective Devices . MCBs

Discrimination:

Whereselectivity between Overcurrent Protective Devices isnecessary to prevent Danger & where required for proper functioning of theInstallation .
( ManufacturersInstructions shall be taken into Account )

Regulation536.2. – “ Plain English “ Regulations is Demandingt hat .

Discrimination)- relates to all Faults . Short circuits . Faults between Line conductors & or Line to Earth Faults .

Regulation536.3. Selectivity between RCDs

Where selectivity between RCD is necessary to prevent Danger & where required forproper functioning of the Installation .
( ManufacturersInstructions shall be taken into Account )“Plain English “Regulations is Demanding that .

 

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O.S.G.– Table 1A .
Currentdemand to be assumed for points of Utilisation & Current using Equipment .

Allother Stationary Equipment . British Standard rated current . or normal current .
( Consultthe Manufactures & / or the Standard & / or ratingplate )

 

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ExternalEarth Fault Loop Impedance :

Regulation313.1 (iv) – Requires an assessment ofthe ( External Earth Fault Loop Impedance Ze ) of that part of the systemExternal to the Installation .
( from -&-s point of view . The Origin ofthe Installation )

 

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Suitabilityof Supply :

Regulation313.1 (v) – Demands an assessment to bemade of the suitability of the Supply for the requirements of the Installation ( Including MaximumDemand )

 

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Regulation 314.4. – 2392-10 as a Domestic Installer .

Thisis important . Each circuit to be electrically separated & connectedindividually & detached from all other circuits where they terminate in a ConsumerUnit .
Theconnections of each circuit Line(s) & Neutral(s) & Circuit protective conductors ( CPCs ) must follow a logical sequence at theirTermination in the Consumer Unit

One MCB Separate Way .

 

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Importantto recognize that an Overcurrent Protective Device ( MCB ) or a ( RCD ) willnot provide Automatic Disconnection when human contact is made between Two LiveParts only . ( Line & Neutral ) an RCD mayAutomatically disconnect if contact is also made Simultaneously with Earth Parts

Thenwe go down the road of “ Touched Voltage“ 50V

ElectricShock under Fault Conditions is when contact ismade with an Exposed Conductive Parts . ( Metal Enclosures/ Class 1 item of Equipment )
( Whichis not live Under Normal Conditions but which has Become Live under EARTH FAULT CONDITIONS )

 

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Workingmy way around the Regulations :

BS-7671:2008)- References to Accessories .

Regulation132.12 )- All electrical equipment mustbe assessable for operation . Inspection & Testing . ( Fault detection ) Maintenance& Repair
(Definitions ) A device . other than current using equipment . associated withsuch equipment or with the wring of an Installation .
“ PlainEnglish “ An accessoryis an item of electrical equipment that does not use anycurrent . Switches or a Socket outlet .

Regulation 421.7. & 526.5. )- Every termination . connection or jointbetween live conductors including the Neutral conductormust be made in a suitable accessory or enclosure
Regulation530.4.2. )- All Accessories must be fitted toan appropriate mounting box or enclosure .ETC.
Regulation 553.1.6. )- A wallmounted socket outlet must be mounted high enough above a floor or work surfaceto prevent damage to the flexible cord of the plug top

Regulation 553.1.6. )- Do Not Mix this up with Part P .
BS-7671does not give Specific Heights for Accessories .

Ifwe look at the ( Building Regulations )
Accessories must be mountedbetween 450 mm & 1200mm from the finished floor level . ETC.