***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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□ Whatare Transient Overvoltages – SURGES . Up to 6.000V. Almost 20 times Mains Supply . [ FAST ] ifnot “ MORE “

Justfor the sake of -&-s . Example .
Direct strike to building. [ Not too worry I have Lighting Protection System . ] WRONG. -&-s . NOT the EQUIPMENT in the BUILDING [ SPD ] may be required .???

 

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Where needed, use [ SPDs ] tested and applied in accordance to BS-EN -61643. Lowvoltage surge - protective devices .

Ifin Doubt . p/289 . Will tell you . BS-EN -61643-11. / BS-EN -61643-21. what direction to go in

BS-EN-62305-1 : General principles .
BS-EN-62305-2 : Riskmanagement .
BS-EN-62305-3 : Physicaldamage & life hazard
BS-EN-62305-4 : Electricaland electronic systems

Transientovervoltages transmitted by the supply distribution system are notsignificantly attenuated downstream in most installations (443.1.1 / Note3)

Section534 key areas – selection of SPDs
SPD in conjunction with RCDs .[ this is where -&-s will be looking g at 2012 ]

(i). SPDs installed before or upstream ofRCD – no tripping problem from overvoltages .
(ii). SPDs installed load side of RCD – nuisance tripping possible .
(iii). RCDs to have immunity to surge currents of 3kA ( 8/20 surge current waveform )
(iv). S Type RCDs meet this requirement

-&-s. There’s a high possibility CSA – Earthing . 534.2.10.
Minimumsize of connecting leads copper (or equivalent):
• 16mm2 for Type 1 SPDs
• 4mm2 for Type 2, 3 SPDs

 

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Fig53.3. p/146 . What the Hell !!!!

( OCPD ) what does it mean ?? : = Overcurrent Protective Device .
( E/I ) what does it mean ?? : Equipment or Installation to be protected against overvoltages . [Main earthing terminal or connecting conductor bar . ]

Example :

534.2.3.5Selection with regard to the prospective fault current and the follow currentinterrupt rating The short-circuit withstand of thecombination SPD and overcurrent protective device (OCPD), as stated by the SPDmanufacturer shall be equal to or higher than the maximum prospective faultcurrent expected at the point of installation.

NOTE 1: The OCPD may be either internal or external to the SPD.

Fault finding, safety precautions and principles Testing,basic principles of circuit protective conductor testing and insulationresistance Electrical symbols and mathematical prefixes. Transformer theory,calculation and practical. Relationship between line and phase voltage in a 3phase system New lighting / surge protection standards BS-EN-62305-1-4 and amendments17[SUP]th[/SUP] Edition wiring regulations

534.2.4Protection against overcurrent and consequences of SPD’s end of life

Protection against SPD short-circuitsis provided by [ OCPDs (see Figures 53.1 and 53.2) which shallbe selected according to the recommended ratings given in the manufacturer’sSPD instructions.

OCPD2 ] may be omitted if the characteristics of [ OCPD1 ] meetthe requirements given in the manufacturer’s instructions.

 

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Section 534 needs to be read fully in conjunction withSection 443 and table 44.3. Three types of SPDs . are

Recognised:

• Type 1 SPD located @ Main switch board
• Type 2 SPD located @ Sub/final distribution boards and consumerunits
• Type 3 SPD located @ Itemsof equipment

 

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• 526.3 . p/131
Every connection shall be accessible for inspection, testing andmaintenance, except for equipment complying with BS-5733 for a maintenance-freeaccessory and marked with the symbol [ MF ] and installed in accordance with themanufacturer’s instructions.

 

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ElectricalInstallation Condition Report ( EICR ).This is a report that will be used for domestic and similar installations up to100A and will include a Condition Report Inspection Schedule.

NOTE: If one or more genuine [ C1 or C2 ] codes are present, this will result in anunsatisfactory Electrical Installation Condition Report being issued. Theoption for further investigation is still available but it is now a tick box onthe inspection schedule.

C1- Danger Present
C2 - Potentially Dangerous

 

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Selectionof Electrical Equipment . p/20

2392-10: Some “ Fundamental Principles “

133.1.1. General . [ Dealing with ] Equipment to complywith standards unless agreed otherwise . [ Exams . -&-s . Part/ P ]
133.1.2.
133.1.3.

 

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Isolation& Switching . 537.1.6.

Ininstallations which include a [ Generator ] which can be used in [ Parallel ] as an additional source of supply . 2012 .
514.15.1. requires thewarning notice - Alternative supplies .

Postedat :
- Originof the installation .
- Meterposition if situated remote from the origin
-at the Consumer unit or Distributionboard to which the alternative or Additional sources are connected .
-at all points of isolation of all sources of supply .

PortableGenerators : 2012. -&-s
Additionalrequirements for protection by Automatic disconnection where the installation& [ GeneratingSet are NOT permanently Fixed ]
551.4.4.
Itis recognised that generators will be used occasionally as a temporary or short term means of supplying electricity.
- Useon a construction site .
-used to supply stalls on street markets .
-external gathering or function attended by the general public . such as acountry show .

O.S.G.- Temporary generators can be divided into two classes . Portable & Mobile .
Regulations. p/32 . ( see Mobileequipment )

Just making a Point . Read between the Line. O.S.G. 2011.
□ PortableGenerators : referenced to the generalmass of the Earth .

BS-7430: 1998 . Where there are extraneous – conductive – parts . or exposed – conductive– parts from other electrical systems present . generator reference earthing .by means of an earth electrode to the general mass of the earth . should beinstalled

Note : thatthis does NOT create a TT – supply arrangements. the supply will be TN-S in form from the generator . the neutral or starpoint being referenced to the general mass of the earth .

● Wherean earth electrode is supplied it will need to be tested by the standard methodusing a [ proprietaryearth electrode résistance tester ]

● Note : that an [ Earth faultloop impedance tester ] cannot be used for this test as the earthelectrode is NOT used as a means of earthing . it is used to reference theportable generator to the general mass of the earth & [ does NOT form partof the Earth Loop ]

Asthe earth electrode is used for reference & NOTas a means of earthing . it’s résistance should . ideally . be less than 200Ω

54.1. if buried generator reference Earthing . & or Bonding conductors should be sized inaccordance with table 54.1. 543.3.1. - 16mm[SUP]2[/SUP][SUP] [/SUP] conductor would generally be adequate for short – term usewhere NO mechanical protection
Just making a Point . Read between the Line. O.S.G. 2011.
□ PortableGenerators : referenced to the generalmass of the Earth .

 

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Usefuljunk : Identification of Conductors .

Table51. p/116
Notes. (3) Only the middle wire of three –wire circuits may be Earthed.

 

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p/398. Condition Report : -&-s . Notes for theperson producing the Report .

Q) What is the reason for issuing this Report .
(3) A) suchas change of occupancy or landlord’s periodic maintenance . 2391-10 .

(1)This Report should only be used for reporting on the condition of an Existing ElectricalInstallation .

(8)Wherever practicable . items classified as “ Danger present “ C1 . shouldbe made safe on discovery . Where this is not practical the owner or usershould be given written notification asa matter of URGENCY . 2391-10

 

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The person ordering the Report .
Wheninitially you are liaising with the [ Client ] regarding carrying out a Periodic Inspection& Test . it is important to establish the following Two Factors .

Extent.
Limitation.

(EICR ) SectionD . p/396 : Extent & Limitations of Inspection & Testing .

Extent : of the electrical installation covered bythis Report .
Agreed Limitations : including the reasons – 634.2.

634.2.
Anydamage . deterioration . defects . dangerous conditions & non-compliancewith the requirements of the regulations . which may give rise to danger .together with any significant limitations of the inspection & testing .including their reasons . shall be Recorded .

 

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2392-10:

Inspection& Testing . is to be carried out in a manner that will [ Ensure ] thesafety of both the Inspector & that of Others . “ Fundamental Principles “ Safety

Mostof the time the Question’s are right in front of our noses . BS-7671:2011 .

Q) On completion of a new installation .the Electrical Installation Certificate would be not signed by the :
i) design engineer.
ii) client . •
iii) person whoconstructed the installation .
iv) inspection &testing engineer .

p/390 : theanswer lies there . ( EIC )

Q) any addition to an existing installationshould . not impair the safety of the existinginstallation :
i) have a similar wiring system to that used inthe existing installation .
ii) be inspected & tested separate from the existinginstallation .
iii) not impair the safety of the existing installation .
iv) have it’s own energy meter separated fromthat of the existing installation .

MinorElectrical Installation Work Certificate for the replacement of a single protectivedevice where an Electrical Installation Condition Report . has identifieddepartures such as :
i)lack of additional protection by RCD .
ii) maximum loop impedance values exceeded .

&the remedial work would involve .

i) replacing a MCB with an RCBO .
ii)replacing a type C – MCB with a . type B. or replacing a 10A MCB with a 6Adevice .

p/393 : Minor Work Certificate makes provision for allthe required test results for the remedial work described .

requires [ Competent person] to certify that the work does not impair the safetyof the [ Existing installation ] &that the design . construction& inspection &testing of the work complies with BS-7671:2011 .

Recall : p/394 . Minor Electrical Installation Work Certificate– ( MEIWC )
This Certificate has been issued to confirm that theelectrical installation work to which it relates has been . Designed . Constructed. Inspection & Tested. Etc .

-&-s □ Recall : Minor WorkCertificate . is intended to be used for Additions & Alterations toan installation that do not extend to the provisionof a new circuit . ( MEIWC )

( MWC ) it doeshave boxes for - Earth continuity .Insulation résistance : Polarity : RCDtimes .

2392-10: ( MWC ) . Comments on [ Existinginstallation ] including adequacy of Earthing & bonding arrangements. 132.16

Q) Records of inspections & test resultsshould be kept during the life of an installation . this will enable :
i) identification of defective parts .
ii) deterioration to beidentified .
iii) landlords to carry out repairs .
iv) correct selection of equipment .

 

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Conductof the Inspection & Testing . “ BasicPrinciple “

Q) Visual inspection of a new installation mustbe carried out :
i) after completion of the installation .
ii) after testing .
iii) after erection & before testing .
iv)during erection & on completion .

Visualinspection is extremely important & it shouldalways precede testing . [ Thiswill stand you fast on Periodic Testing ]
Thepurpose of the [ Visual inspection ] is to confirm the following aspects of theinstallation :
i) Equipment complies with standards in accordance with the requirements of BS-7671:2011 .
ii)Equipment is correctly selected & erected . in accordance with theRegulations . taking into account manufactures instructions .
iii) not visibly damaged or defective so as toimpair Safety .

Visualinspection : Inspection . 611.1. /611.3.
Initial Verification :
611.1. Inspection shallprecede testing & shallnormally be done with that part of the installation under inspectiondisconnected from the supply .

SmartMeters : The need for meter installersto [ Visually ] check consumer’s electrical equipment adjacent to the electrical intakeequipment .
Inspectors. to check the adequacy of the earthing arrangement before [ Re-energising the installation ] many existing installations are likely to have inadequate oreven non- existent earthing arrangements.

2392-10: I must Stress this : Tightness of the connection of the [ meter tails ] at the main switch in the Consumer Unit . – [ Loose connections ]

2392-10: Q) Which one of the following tests can only be carried out after the supply is connected :
i) prospective faultcurrent . ( PFC )
ii) insulation résistance . ( dead )
iii) polarity . ( dead )
iv) continuity of protective conductors . ( dead)

Q) The commissioning process takes place “ When “ : A) [ After ] an installation has been inspected &tested .
Let’sopen it up .
Q) When should the commissioning process Not take place . After an installation has been inspected &tested .

 

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2392-10:

p/389. Reminder .

NewWork . [ Initial Verification ]

(EIC ) will indicate the responsibility fordesign . construction . inspection & testing .
-&-. to New workor further work on an Existing installation .

Q) The person who tests & signs the ( EIC) for an electrical installation should be: - &-s [ any Certification &Reporting ]
A) Competent person .

Informative.
i): ii) : iii) :

p/389 . (iv) Competent person. will . as appropriate to their function under [ i) : ii) : iii) ]

(T) 632.4. this a must . Chaps :icon_bs:
Defectsor omissions revealed during inspection & testing of the installation workcovered by the [ Certificate ] shall bemade good before the certificate is issued .


2391-10: You have my Undivided Admiration . You chaps. don’t get the recognition that you. deserve .
Approved Electrician . that to me is a BIG patin the Back .

Yourprofessionalism is OUT standing . -&-s do not do you Justice . “ Approved“

 

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2392-10:

632.4. Reminder . before an(EIC) isissued . any defects or omissions must be . made good . -&-s