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
Inspector - has responsibilityplaced upon him as to the Safety of the Installation . Visual Inspection )- is Essential to assess the safety of anInstallation before testing takes place .
Verification . All measures by means of which compliance of the electricalinstallation with the relevant requirements of BS-7671 are checked .comprising Inspection . Testing & Certification .
( IR ) Insulation Résistance Testingrequires different test voltages for “Certain Circuits “ indentify what circuit(s) require the following voltages . 250V. 500V . 1000V
Competent. Persons responsible for Inspection & Testing . :19:
Competent person . A person who possesses sufficient technicalknowledge . relevant practical skills & experience for the nature of the electricalwork undertaken & is able at all times to prevent danger & where appropriate. injury to him / herself
Inspection& Testing . of the installation will be your responsible for decidingwhether or not an Installation complies with the Regulations in their Entirety. BS-7671:2008
2392-10: Regulation. 134.1.1. Therefore the person carryingout the Installation . ( p/19 ) – ( p/21 ) Goodworkmanship by Competent persons or Person . Etc
Regulation . 610.5. Inspection & Testing of any Electrical Installation Work mustcomply . ( 156) Regulation . 610.5. The Verification shall be made by a CompetentPerson . First Amendedment . ▼▼▼
Competent person . A person who possesses sufficient technicalknowledge . relevant practical skills & experience for the nature of the electricalwork undertaken & is able at all times to prevent danger & where appropriate. injury to him / herself
ConditionReport Inspection Schedule for Domestic & Similar Premises with up to 100ASupply .
Final Circuit(s)
Identification of conductors ( 514.3.1. ) Cables correctly supported throughout their run ( 522.8.5. ) Condition of insulation of live pars ( 416.1. ) Non-sheathed cables protected by enclosure in conduit . ducting ortrunking ( 521.10.1. ) □ To include the integrity of conduit & trunking systems ( metallic & Plastic )
Adequacy of cables for current-carrying-capacity with regard forthe type & nature of installation ( Section 523 ) Coordination between conductors & overload protectivedevices ( 433.1. : 533.2.1. ) Adequacy of protective devices . type & rated current forfault protection ( 411.3. ) Presence & adequacy of circuit protective conductors ( 411.3.1.1. : 543.1. ) Wiring system(s) appropriate for the type & nature of theinstallation & external influences (Section 522. ) Concealed cables installed in prescribed zones ( see Section D . Extent & Limitations’ ) (522.6.101. ) Concealed cables incorporating earthed armour or sheath . or runwithin earthed wiring system . or otherwise protected against mechanical damagefrom nails . screws & the like . see Section D . Extent & limitations .( 522.6..101 : 522.6.103. ) Provision of additional protection by RCD not exceeding 30mA . □ for all sockets-outlets of rating 20A orless provided for use by ordinary persons unless an exception is permitted ( 411.3.3. ) □ For supply to mobile equipment not exceeding 32A rating for use outdoors (411.3.3. ) □ For cables concealed in walls or partitions ( 522.6.102 : 522.6.103. : Provision of fire barriers . sealing arrangements & protectionagainst thermal effects ( Section 527 ) Band ii cables segregated / separated from band 1 cables ( 528.1. ) Cables segregated / separated from communications cabling ( 528.2. ) Termination of cables at enclosures - indicate extent of samplingin Section D of the report ( Section 526. ) □ Connections soundly made & under no undue strain 526.6. □ No basic insulation of a conductor visible outside enclose ( 526.98 ) □ Connections of live conductors adequately enclosed 526.5 □ Adequately connected at point of entry to enclosure ( glands .bushes etc. ) 522.8.5. Condition of accessories including socket-outlets . switches &joint boxes ( 621.2 – ( iii ) Suitability of accessories for external influences ( 512.2. )
Examples of items requiring Inspection for an ElectricalInstallation Condition Report .
A Visual Inspection shouldfirstly be made of the External Condition of al Electrical Equipment which isNot – Concealed . :19:
Further detailed Inspection . including partial dismantling ofequipment as required . should be carried out as agreed with the personordering the work . ( 612.2. )
State:- Indentify the type of circuit thatwould require the following applied voltages when conducting an Insulation Résistancetest . :19:
i) 250V . ii) 500V . iii) 1000V .
i) SELV / PELV . ii) Systems up to & including 500V . iii) Systems over 500V but under 1000V .
Short& Simple . -&-s
Locations ) containing a Bathor Shower .
Additional protection for all low voltage ( LV ) circuits by RCD not exceeding 30mA ( 701.411.3.3. ) Where used as a protective measure . requirements for SELV orPELV met . ( 701.4.4.4.5. ) Shaver sockets comply with BS-EN 61558-2-5 . formally BS 3535( 701.512.3. ) Presence of supplementary bonding conductors . unless not requiredby BS-7671:2008 . ( 701.415.2. ) Low voltage ( e.g. 230 volt ) socket-outlets sited at least 3m from zone 1 ( 701.512.3. ) Suitability of equipment for external influences for installedlocation in terms of ( IP ) rating (701.512.2. ) Suitability of equipment for installation in a particular zone . (701.512.3. ) Suitability of current-using equipment for particular positionwithin the location ( 701.55. )
AFundamental principle of ELECTRICAL SAFETYis that NO SINGLE FAULT CONDITION should cause ahazardous situation . Plain English .
Asthe FirstAmendment says .
Definitions . Fault Protection . p/28 . Protection against electric shock under ( Single Fault Conditions)
Note )- for low voltageinstallations . systems & equipment . fault protection generallycorresponds to protection against indirect contact . mainly with regards tofailure of basic insulation . Indirect contact is “ contact of persons orlivestock with exposed-conductive-parts which have become live ( UNDERFAULT CONDITIONS “
Earth electrodes located at such a distance from one another thatthe maximum current likely to flow through one of them does not significantlyaffect the potential of the OTHER(S) .
Current – Using Equipment (Permanently Connected )
• Condition of equipment in terms of ( IP ) rating etc . ( 416.2.) • Equipment does not constitute a fire hazard ( Section 421 ) • Enclosures not damaged / deteriorated so as to impair safety (621.2. (iii)) • Suitability for the environment & external influences (512.2. ) • Security of fixing (134.1.1. ) • Cable entry holes in ceiling above luminaires . sized or sealedso as to restrict the spread of fire .List number & location of luminairesinspected ( Separate page ) • Recessed luminaires ( Down lights )
1) Correct type of lamps fitted . 2) Installed to minimise build-up of heat by use of “ fire rated “fittings . insulation displacement box or similar ( 421.1.1.1. ) 3) No signs of overheatingto surrounding building fabric (559.5.1. ) 4) No signs of overheatingto conductors / terminations ( 526.1. )
TheImpedance of the Earth connection must be low enough to ensure that sufficient currentcan flow through the protective device so that it disconnects the supply quickly( 0.4 sec ) & Voltage on the Earthconnection does not RISE more than( 50V )
RCDsoperate at much lower Fault Currents . ◄◄◄ :19:
Additional protection shall be provided for all circuits of thelocation . by the use of one or more RCDs having the characteristics specified inregulation 415.1.1. Note : see also Regulation 314.1. ( iv ) & 531.2.4. concerningth avoidance of unwanted tripping . p/166
701.411.3.3. Additionalprotection by RCDs
Additional protection shall be provided for all [ low voltagecircuits of the location ] . by the useof one or more RCDs having the characteristics specified in regulation 415.1.1. Note : see also Regulation 314.1. ( iv ) & 531.2.4. concerningthe avoidance of unwanted tripping . p/199
Theonly wording that is changed . 705.415.2.1. ( p/183 ) – ( p/216 )
Note : Where a metal grid isnot laid in the floor a TN-C-S supply is not recommended .
Note : Where a metal gridis not laid in the floor . the use of a PME Earthing facility as the means of Earthing for the electrical installationis not recommended .
Thedifference between the First Amendment & 17[SUP]th[/SUP]Edition
Section 705 : 705.1. Scope :
Theonly wording that is changed .
Rooms . locations & areas for household applications &similar are not covered by this section . p/183 . Note : Section 705 does not cover electric fence installations .Refer to BS-EN 60335-2-76 & BS-EN 6100-1.
Rooms . locations & areas for household applications &similar are not covered by this section . p/216 . Note : Section 705 does not cover electric fence installations .Refer to BS-EN 60335-2-76
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