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# Electrical Thumb Rules You MUST Follow (1)

Home / Technical Articles / Electrical Thumb Rules You MUST Follow (1)

## Electrical Thumb Rules For:

### Cable Capacity

• For Cu Wire Current Capacity (Up to 30 Sq.mm) = 6X Size of Wire in Sq.mm
Ex. For 2.5 Sq.mm = 6×2.5 = 15 Amp, For 1 Sq.mm = 6×1 = 6 Amp, For 1.5 Sq.mm = 6×1.5 = 9 Amp
• For Cable Current Capacity = 4X Size of Cable in Sq.mm, Ex. For 2.5 Sq.mm = 4×2.5 = 9 Amp.
• Nomenclature for cable Rating = Uo/U
• where Uo = Phase-Ground Voltage, U = Phase-Phase Voltage, Um = Highest Permissible Voltage

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### Current Capacity of Equipment

• 1 Phase Motor draws Current = 7Amp per HP.
• 3 Phase Motor draws Current = 1.25Amp per HP.
• Full Load Current of 3 Phase Motor = HPx1.5
• Full Load Current of 1 Phase Motor = HPx6
• No Load Current of 3 Phase Motor = 30% of FLC
• KW Rating of Motor = HPx0.75
• Full Load Current of equipment = 1.39xKVA (for 3 Phase 415Volt)
• Full Load Current of equipment = 1.74xKw (for 3 Phase 415Volt)

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### Earthing Resistance

• Earthing Resistance for Single Pit = 5Ω, Earthing Grid = 0.5Ω
• As per NEC 1985 Earthing Resistance should be < 5Ω.
• Voltage between Neutral and Earth <= 2 Volt
• Resistance between Neutral and Earth <= 1Ω
• Creepage Distance18 to 22mm/KV (Moderate Polluted Air) or
• Creepage Distance = 25 to 33mm/KV (Highly Polluted Air)

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• Minimum Bending Radius for LT Power Cable = 12 x Dia of Cable.
• Minimum Bending Radius for HT Power Cable = 20 x Dia of Cable.
• Minimum Bending Radius for Control Cable = 10 x Dia of Cable.

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### Insulation Resistance

• Insulation Resistance Value for Rotating Machine = (KV+1) MΩ.
• Insulation Resistance Value for Motor (IS 732) = ((20xVoltage (L-L)) / (1000+ (2xKW)).
• Insulation Resistance Value for Equipment (<1KV) = Minimum 1 MΩ.
• Insulation Resistance Value for Equipment (>1KV) = KV 1 MΩ per 1KV.
• Insulation Resistance Value for Panel = 2 x KV rating of the panel.
• Min Insulation Resistance Value (Domestic) = 50 MΩ / No of Points. (All Electrical Points with Electrical fitting & Plugs). Should be less than 0.5 MΩ
• Min Insulation Resistance Value (Commercial) = 100 MΩ / No of Points. (All Electrical Points without fitting & Plugs).Should be less than 0.5 MΩ.
• Test Voltage (A.C) for Meggering = (2X Name Plate Voltage) +1000
• Test Voltage (D.C) for Meggering = (2X Name Plate Voltage).
• Submersible Pump Take 0.4 KWH of extra Energy at 1 meter drop of Water.

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### Lightning Arrestor

Arrestor have Two Rating:

1. MCOV=Max. Continuous Line to Ground Operating Voltage.
2. Duty Cycle Voltage. (Duty Cycle Voltage > MCOV).

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### Transformer

• Current Rating of Transformer = KVA x 1.4
• Short Circuit Current of T.C /Generator = Current Rating / % Impedance
• No Load Current of Transformer =< 2% of Transformer Rated current
• Capacitor Current (Ic) = KVAR / 1.732xVolt (Phase-Phase)
• Typically the local utility provides transformers rated up to 500kVA For maximum connected load of 99kW,
• Typically the local utility provides transformers rated up to 1250kVA For maximum connected load of 150kW.
• The diversity they would apply to apartments is around 60%
• Maximum HT (11kV) connected load will be around 4.5MVA per circuit.
• 4No. earth pits per transformer (2No. for body and 2No. for neutral earthing),
• Clearances, approx.1000mm around TC allow for transformer movement for replacement.

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### Diesel Generator

• Diesel Generator Set Produces = 3.87 Units (KWH) in 1 Litter of Diesel.
• Requirement Area of Diesel Generator = for 25KW to 48KW = 56 Sq.meter, 100KW = 65 Sq.meter.
• DG less than or equal to 1000kVA must be in a canopy.
• DG greater 1000kVA can either be in a canopy or skid mounted in an acoustically treated room
• DG noise levels to be less than 75dBA at 1 meter.
• DG fuel storage tanks should be a maximum of 990 Litter per unit. Storage tanks above this level will trigger more stringent explosion protection provision.

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### Current Transformer

Nomenclature of CT:

• Ratio: input / output current ratio
• Burden (VA): total burden including pilot wires. (2.5, 5, 10, 15 and 30VA.)
• Class: Accuracy required for operation (Metering: 0.2, 0.5, 1 or 3, Protection: 5, 10, 15, 20, 30).
• Accuracy Limit Factor:
• Nomenclature of CT: Ratio, VA Burden, Accuracy Class, Accuracy Limit Factor.Example: 1600/5, 15VA 5P10  (Ratio: 1600/5, Burden: 15VA, Accuracy Class: 5P, ALF: 10)
• As per IEEE Metering CT: 0.3B0.1 rated Metering CT is accu­rate to 0.3 percent if the connected secondary burden if imped­ance does not exceed 0.1 ohms.
• As per IEEE Relaying (Protection) CT: 2.5C100 Relaying CT is accurate within 2.5 percent if the secondary burden is less than 1.0 ohm (100 volts/100A).

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## Quick Electrical Calculation

 1HP = 0.746KW Star Connection 1KW = 1.36HP Line Voltage = √3 Phase Voltage 1Watt = 0.846 Kla/Hr Line Current = Phase Current 1Watt = 3.41 BTU/Hr Delta Connection 1KWH = 3.6 MJ Line Voltage = Phase Voltage 1Cal = 4.186 J Line Current = √3 Phase Current 1Tone = 3530 BTU 85 Sq.ft Floor Area = 1200 BTU 1Kcal = 4186 Joule 1KWH = 860 Kcal 1Cal = 4.183 Joule

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### Jignesh Parmar

Jignesh Parmar has completed M.Tech (Power System Control), B.E (Electrical). He is member of Institution of Engineers (MIE), India. He has more than 20 years experience in transmission & distribution-energy theft detection and maintenance electrical projects.

1. PP DEY
Jul 18, 2023

THANKS FOR SHARING THE THUMB RULES

Dec 08, 2023

Dear parmar ji,
You are a great person, of Modi vision, make in India, you are making our indian technicals lerning strong.
Thanks for best effort.

2. Paulson John P.
Jun 23, 2023

useful for engineers those who works in projects

3. MK Prakash
Jan 20, 2023

Perfect

4. v prashanth
Dec 03, 2022

NICE AND PRACTICALLY APPLICABLE METHODS INVOLVED ….THANKS

5. ABUL FAJAL
Nov 08, 2022

i learned many things by your post. thank you .

6. RAJESH CHAUHA N
Jun 16, 2022

Dear sir,
how to make calculate , cable size 3cx70 sqmm copper pvc insulated double gi strip armoured,

pl clear this point the conductivity of armour shall not less then 75% of the conductivity of larg core
how many copper strip use for the conductivity maintain.

7. Bipin Kumar Singh
Feb 14, 2022

What would be current carring capacity of cable in 3phase system?

8. Satish Wagh
Feb 01, 2022

Very good info. for all engineers

9. Hitendra Marge
Dec 06, 2021

Dear sir , need overload current carrying capacity for MV cable with trefoil and flat touching condition with different hours.
Generally 1 /2/3/4/6/8/10/12/24 hour run with 60% / 75%/90% & 30% overload condition with respectively above mentioned time durations so please how can calculate in easy format.

10. V Anguchamy
Nov 18, 2021

Need Cable current carrying capacity for 3 Phase Cable

11. Shah
Jan 18, 2021

can we use 2 x 16sq.mm x 4core and 1 x 10sq.mm x 4core power cable instead of 1 x 35sq.mm x 4core cable for the connectivity of Diesel Genset (60 KVA) to ATS panel 20 feet apart.

• ozigi
Jan 20, 2021

2x16mm2 4-core cable which is 2 run of 16mm2 4-core cable is more than enough to connect 60kVA generator to ATS panel
giving that the generator current = 86.6A

• SHIVAPRAKASH
Mar 18, 2021

We Have a powerloom factory…with each one has 330 watts 3 phase induction motor voltage -220 freq-50hz
we have used 4 sq mm for mainline and 2.5sqmm for each motor for 12 motors.
Can We Connect that same 4 sq.mm for another 12 motors or we have to add 4 sq mm wire…Help me with your knowledge

• Prem Singh
Mar 05, 2021

YES.
We bundled conductors instead of single conductors for ac transmission to reduce skin effect.
If you provide two cables 4Cx35 Sq mm for one cable 4Cx35 Sq. mm then the system is sufficient and addition of 4Cx10 Sq mm will make it extra strong.

Dec 12, 2021

Yes you can

12. Sudhakar
Dec 11, 2020

Hi Sir,

In a substation we use different connectors, like, bus support, couplers, body & cap connector etc, I would like to know what each component is rated for with respect to ampacity. How can we calculate that, is there a way to do that.

13. Chandraprakash G
Nov 29, 2020

Excellent and neat write up, keep the great work !!

14. murali nagarajan
Nov 19, 2020

3phase 40A energy meter 17Nos in one apparetment.
How much amps switch rating and transformer is required?

15. saranraj.M
Sep 17, 2020

Typically the local utility provides transformers rated up to 1250kVA For maximum connected load of 150kW.
Power factor*KVA=KW
0.8*1250=1000KW
How it will calculate?

16. Hemant Samal
Jul 16, 2020

Sir, one of my client wants to take connection having his required load 70 KW. In fact I have maximum feeder capacity in the existing panel 100 AMP TPN,MCCB-16 KA. Please suggest me the Feeder specification, so that I can install it in my panel in the spare box. also please eleborate the formula to select.

Nov 26, 2019

Thank you sir. This is very needful to us.

18. Raj kumar
Oct 27, 2019

Sir,

I need to know the load calculations of
2core 1sqmm al ar cable = Amps
1sqmm cu cable = Amps

19. Subhro
Jul 24, 2019

Tor electrical calculation should we take 1HP= 735.5W or 746W

• Anup Kumar
Oct 13, 2020

1HP=746W

20. C P
Jul 15, 2019

Dear sir
Twin core flat aluminium pvc insulated cable when we are supply current one core than earthing second core why ?

21. Abhishek Robinson
Jul 09, 2019

Dear sir

I need your expertise ON TRIPOING OF 220KV EHV transmission line, during lightening.

22. udeerna kV
Jul 08, 2019

Very very nice ..very very useful informations &Calculations..thank u very much

23. V PRASHANTH
Jul 04, 2019

For 4Cx 6sqmm cu at cable, you can go with 4Cx 25 sqmm Al AR XLPE cable. And for 3Cx4sqmm you go with 16sqmm if the length is less than 80 to 100mts.

24. Nanhey lal chauhan
Jan 13, 2019

load calculation of3.5*300 sq mm al. cable

25. Pramod
Dec 31, 2018

For single core house wiring to 1.5 sq. Mm. How much current take ?

26. N Satyanarayana
Nov 16, 2018

2800KW, 12Amps 1 phase AC load and distance between incoming supply source to load point is 1500mtr. Cable laid in under ground and HDPE pipe. now can you please suggest cable size and voltage drop calculation

27. avinash lahane
Oct 31, 2018

How to select ct burden when current 1000A and voltage 433 v for metering and capacitor panel realy operating purpose.

Regards
Avinash Lahane
M-9225305991

28. YECHURI SAI AKHIL KUMAR
Oct 14, 2018

i want to replace 4c*6sqmm copper armed cable with aluminium armed cable can u suggest the thickness of aluminium cable .and also i want to replace 3c*4sq mm copper with aluminium can u please suggest the thicknesses of aluminium cable

29. Samrat sinh Jhala
Sep 13, 2018

How to calculate the full load current of a 3 phase submersible,440V?

30. somasundaram n
Sep 04, 2018

Sir
What are the details of motor installed in washing machine to be found out to select strength of wire ie. 2.5 s.qm or 4.5 sq.m or 1.5 sq.m wire to give power supply?

whether 15 amp.plug and socket can be powered with 1.5 sq.m flexible wire already given for 5 amp socket in the boar or more than 1.5 sq. metre strength wire to be used?

Somasundaram N

31. Sushil Kumar
Aug 03, 2018

Dear Sir
Can We use 4mmx4core copper armoured cable for 10HP motor coupled with 60LPM hyraulic pump. Application is for chopping/cutting of scrap sheet after blanking

Jun 26, 2019

pls see size of cable. i think it should be higher. you can follow chart for “current vs size of cable”. also different chart for Cu and Al is there

32. Nilesh
Jul 20, 2018

Can I use 25x2x0.75sqmm twisted,shielded cable instead of 50×0.75sqmm shielded cable?
Application :- I need to transmit 230VAC power from stepper drives to motor.

33. SIVAKUMAR G K
Jun 06, 2018

SIR,
FOR 100 KW SOLAR PLANT CAN I USE 4C*70 SQ.MM(COPPER) TELL ME ITS ENOUGH.FROM ACDB TO EXISTING PANEL

34. Gnanaguru
May 16, 2018

Hi fella,

I came across this website and got lost in wire Vs cable hurricane :) Later in comments I’ve seen cables AKA “bunch of wires” explanation. Where I got stuck is, according to your statement

“Cable Current Capacity = 4X Size of Cable in Sq.mm, Ex. For 6 Sq.mm = 4×6= 24 Amp.”

Yet in the mean time, I’ve witnessed mine sq.mm wire stood against the current capacity of around 28A for nearly 30minutes!!! Its details are Unsheated,Copper made,No. of wires/Wire dia metre=85/.30. So I’m expecting 6xSize in sq.mm instead of 4XSize in sq.mm. So I want you to clearly tell me what does wire Vs cable means?

May 12, 2018

its really helpful i am very thank full to you for your this kind of act.

36. ansari
Mar 30, 2018

hi
finaly i found nice web site to improve my knowledge. i have to know if i communicates RS485 data with 1.5sq mm 2 core twisted wire without sheld and run the wire 60 mtrs what will happen.

37. vignesh
Mar 24, 2018

Here we using the load 3.6Amps and the same we are using the wire 2.5Sq.mm.If it is ok or we need to change.

38. Aniesh Mathew
Mar 18, 2018

Hi,

We have the Main Panel MCCB of 400A 4P and the load is 120kVA. The client has provided raw power using 4 core 95Sqmm Aluminum Armoured cable. Please let me know whether the raw power cable is fine for our load?

Also what is the load 95sqmm can take?

May 12, 2018

Hi,

According to load the cable size is good enough, and the cable can carry up to 220A current which means 120Kw or 140KVA

39. H M Khyruzzaman
Feb 03, 2018

Thanks. Very effective information.
Please give me a clear idea how can I find the contactor rating & over load relay rating for Star-delta Starter. Give me this example for 30kW motor.

Dec 30, 2017

41. Vijay Kumar Job
Dec 18, 2017

Please correct 2.5×4 = 9Amps to = 10Amps.
in cable current capacity thumb rule.

42. Bello Babayo
Dec 12, 2017

Intresting and educative forum for power engineers

43. Benson Barasa
Aug 06, 2017

This forum is indeed amazing quite educative.
Keep up the good work.
Thank you.

44. pn iyengar
Jul 31, 2017

Sir, How do the GEB pole lines are identified for phase , neutral and earthing. Reason for my asking is all the lines ( Either 3 or 5 for single and 3 phase ) are same and there is no distinction. Recently in our street light pole tuble light connection, an electricians has given some wrong connection by joining 2 wires either in phase or in neutral. Because of this many of our street people have lost TV, Fridge, AC, Digital wall clock etc. The GEB officials said that Munipal contractor has done the mistake while rectifying the defect in the pole street light. This is the reason why want to know for easy identification of these Phase, Neutral and Earthing wires of GEB Pole. pls. explain with sketch or drawing for easy understanding.

45. Joseph Puduvala
Jul 02, 2017

Dear Sir,

Would you please advise how can I connect 2 numbers of single phase 3000VA 230V 50 HZ UPS
in Parallel for redundancy… Appreciate your early response

Thanks and regards
Joseph Puduvala

• vinay kumar
Nov 15, 2017

Hi,

These single phase ups can be connect in parallel only when there Output voltage and frequency are same. so please communicate with service provider to set voltage and frequency of both ups on same value and then your can synchronize the ups.

Regards

Vinay kumar

46. Arun
Apr 25, 2017

It’s awesome page..I love to visit the page but there are no answers posted for all the questions asked by the Engineers..And I would love to join this group on LinkedIn or FB to gain some knowledge about the EEE.Thank you so much guys for your time and patience.
Anyone please suggest me a book or a site to learn from basics to the core subject of Electrical Engineering including the calculations.
.You guys TC!!

47. akshihs
Apr 21, 2017

Current capacity of aluminium cable

48. Sreenath
Feb 15, 2017

Hi i have a question
we require 100KVA DG as part of the factory setup can anyone explain how much capacity of transformer will be needed, is there a possibility to determine the transformer capacity based on the DG or let me know if you need the machinery list thanks in advance

• vinay kumar
Nov 15, 2017

Hi,

To calculate capacity of Transformer,you have to calculate the load of plant and also consider extension of load in future. then maximum load should be less than 80% of transformer capacity.It does not depend on your D.G availability.

Thanks
Vinay

Mar 11, 2018

In a 3 phase motor we use 10 mm cable one phase taking 40 amp for example how much total current of this motor

49. Rohan Weerarathna
Jan 23, 2017

Can you give motors equations for Induction motors, DC Motors ect.

50. Yogender
Jan 05, 2017

What is equivalent size of cable will be used for earthing of DG sets and Transformer instead of cu /GI strip
Is considered the same cross sectional area or how to calculate

51. Mubbashir
Dec 27, 2016

Esteemed sir

I want to know how to calculate current carrying capacity per square mm Arial bunched cable.

52. Franco George
Dec 22, 2016

Sir, please give details about how to bend an earth cable to be connected to diesel generator of 25 KVA. Give me an idea how to bend it.

53. Muktinath Shil
Dec 16, 2016

Dear Sir,
I want to know what is required AC cable size (in sqmm) for solar on grid 3phase 12.5kW inverter for inverter to ACDB?

• atul
May 11, 2018

4cx16 sqmm Cu.

54. Ravindra Raghuwanshi
Dec 06, 2016

We have infrared lamp resin curing plant & paper dryers. Total load is 330 KW. Connected with neutral and 3 phases i.e.each phase will have a load of 110 kw. Current 500 amp. What should the cable size and 3.5 core or 4 core. We will prefer copper.

55. Rajendra Singh
Oct 07, 2016

how can we have check the copper nd aluminium cable size according to load via formula or trick ?
this is very urgent for me, pls help me sir ASAP.

56. M Ajay
Sep 28, 2016

Dear Sir,

your above mentioned information is very useful.But please mention the load capacity of aluminium cables also..for 30sqmm copper cable we can put a load of 120A??

57. Hasrat ali
Aug 25, 2016

Gd evening sir
Pls told me sir
How will be calculate cable size in mm^2
Pls told me a short trik
For example which size of cable should be use for 2500amp rating braker
Pls sir as soon as possible rply me

58. sujith thankachan
Aug 23, 2016

Thanks a lot sir
this helping me more……..

59. Priyanka Waikar
Aug 15, 2016

i just want solution for this. if i want to pass current of 1600 Ampere so what size of cable should i select?? cable size should in MM^2

Aug 21, 2016

It should be 400 Sq mm

60. shivam
Jun 27, 2016

Sir, can you say that how a dc current of 2.5 amps will flow through a wire of resistance 60 ohms? input is 36 volts 11 ah battery

61. Rholand Forescal
Jun 20, 2016

Sir please tell me why 1hp single phase motor is 7ampere in single phase motor chart in ampere. But if we use the formula in ohms law to get ampere in single phase I = hp / VxExPF we only get only 4.23 ampere when voltage is 230v power factor is 0.9 and i used 0.85 efficiency.. Please teached me how to prove the electrical thumb rules.

62. Isuru
May 31, 2016

what is the difference between “Cu Wire Current Capacity” and Cable “Cable Current Capacity”?

• pawan bhardwaj
Aug 29, 2016

For Cu Wire Current Capacity (Up to 30 Sq.mm) = 6X Size of Wire in Sq.mm
Ex. For 2.5 Sq.mm = 6×2.5 = 15 Amp, For 1 Sq.mm = 6×1 = 6 Amp, For 1.5 Sq.mm = 6×1.5 = 9 Amp
For Cable Current Capacity = 4X Size of Cable in Sq.mm, Ex. For 2.5 Sq.mm = 4×2.5 = 9 Amp.

63. gurpreet
May 28, 2016

Plz tell me how to calculate size of generator set for a specific submersible pump set i.i for specific hp motor? Thanks alot

64. Swapnendu Sil
May 05, 2016

pls tell me sir what cable needed for 32amp industrial socket and how we can determine if we need aluminium cable or cu cable or need 3 phase or single phase in general?

65. Gopi nath
Feb 24, 2016

Super sir

66. rudramurthy
Dec 17, 2015

7/16 cable size meanes what is the sqmm cable size in 3 phase supply 30kva load

67. Balu B Nair
Dec 07, 2015

wonderful informative portal….!!!

Oct 15, 2015

A perfect compilation. Thanks Jignesh. (Author)

69. shah faisal
Sep 29, 2015

how i find cable for a suitable load like a if load is 23 which cable is-perfect for this load and how i find by formula ?

• MD kashif
Nov 17, 2015

Plz tell me how to tabulate the armoured cable size for a particular load.

70. gurjit
Aug 11, 2015

i am living in FLAT WITH 3 BED ROOMS ONE DRAWING ROOM AND HAVE 5 ACs 2 TR AND WASHING MACHINE INDUCTION COOKER AND MICROWAVE WITH GEYSERS 25 LITERS IN BED ROOMS AND KITCHEN AND THE LOAD GRANTED IS 8KW.
THE EARTHING WIRE FROM MCB BOARD ON FIRST FLOOR TO METER ON GF IS OF 1 MM SQUARE .
IS THIS ENOUGH OR SHOULD I REPLACE WITH HIGHER CAPACITY

• Rehan
Oct 08, 2015

No Its not enough

If you are having a single phase meter use 1 no of 4 sq mm Cu wire
and if you are having a 3 phase meter use 2 nos of 4 sq mm wires

71. ankesh mishra
Aug 02, 2015

Tell me the short cut for calculating load for a flat

72. Deepak Kumar
Jul 06, 2015

Please tell me how to find current rating of the conductor

73. mohan dass
Jul 03, 2015

Can we use 2 run of 25 mm sq instead of 50 mm sq cable of Cu. If yes then tell me full details and If not then tell me also full details.

74. manish chovatia
May 21, 2015

How many distance between transformer and diesel genrator as per ie rules

75. sowmya
May 01, 2015

I have a current transformer with 1 main meter outside the building and a control panel having 5 CT meters with black round coils inside the building. I want to know, A) when current pass through the Transformers, will the current be reduced or be the same and after that B) when current pass through the CT meters with black round coils, will the current be reduced or be the same. C) in the above process will the reading of the main meter be same or different, from the total reading of all the 5 CT meters.

Apr 07, 2015

What is the simple formula for electrical, current , voltage

Apr 07, 2015

Thanks sir u help for electrical problem .

78. omar
Feb 08, 2015

we known low pf increase line current so does it increase kwh reading in metering…but pf varation is related also actually totally in reactive part…so what is the impact of pf in metering.

79. Bassey Friday
Jan 31, 2015

• Etop Inyang
Aug 22, 2015

Is your generator sets for emergency supply or prime supply? For Prime you can load up to 100% and 70% for emergency generator sets.

80. mdmukhter
Jan 03, 2015

I want to take part in to the technical debates and weekly technical discussion.

81. abdelsalam mikky
Dec 22, 2014

How diesel engine frame should be grounded (I think shall be two earthing diagonal points ) according to NFPA 70 (NEC), could you please provide the supporting standard cod of this

• Edvard
Jan 03, 2015

Every Genset has predefined points to ground engine frame. Don’t forget to ground gas reservoir if it exist.

Nov 18, 2014

How to calculate Cable sizes for the Below in thumb rule,
01.Single core cable above 30Sqmm
02.Three phase cable size.
Pls send it with a clear Example

83. rahul
Oct 15, 2014

what is maximum distance between VCB panel and transformer at 11 kv voltage supply using HT cable of size 3cX95sqmm. Is it ok that transformer is installed at 150 meter away from VCB panel.

• ali
Nov 08, 2014

minimum 6 mtrs

84. JOYDEEP KUNDU
Oct 06, 2014

SIR I JUST WANT TO KNOW THAT IN 3PHASE 4 WIRE ELECTRICAL DISTRIBUTION SYSTEM WHY THE RADIUS OF NEUTRAL WIRE IS LESS THAN OTHER WIRE?

• kalpesh
Aug 06, 2015

Because in 3 phase 4 wire system only unbalance current pass from the nutural so current is never higher then half of the phase current,so purpose of aluminium saving its samller size then phase in power cable of higher size

85. balu
Oct 01, 2014

Dear sir,

Thanks&Regards
Vagh Balu R
7698260140

• Huj
Oct 03, 2014

Dear Jebalu, are ju crazy. There is inernet, no personalities!

86. Arnel
Sep 22, 2014

what is the meaning of 2×6+4 for wire sizing?

87. R Knight
Sep 21, 2014

What do you reckon on SWA 3 phase and Neutral Cable size?

Circuit 1
primary fuses, 16A and 20A = 36A
However, connected load is 9kVA and 3kVA = 17.3A and average consumption is 3kVA and 2kVA respectively, giving ~ 8A

Circuit 2
Primary fuses, 40A, 16A, 16A and 16A = 88A
However, nominal current is 33A, 6A, 8A and 11A, giving ~ 58A

Circuit 2
11kw fan with a 32amp supply

on Cable run of 150m

88. kushvendra tyagi
Sep 17, 2014

If the load requirement is 1200 kva , what kind of independent feeder should be considered , 11th or 33 kv

89. Glenn
Sep 03, 2014

Hi need clarification to choose between 3 core, 3.5 core and 4 core for cable selection application. I know we choose 3.5 core and above in case of unbalanced loads any advice on making selection more clear is greatly appreciated

90. Thuong.nguyen
Jul 12, 2014

1 Phase Motor draws Current = 7Amp per HP.
Full Load Current of 1 Phase Motor = HPx6
I think full load current of 1 phase is too high, for examples, in catalog of manufacture, current of 1 phase motor 4HP only about 12A. Moreover, please clarify why percent of draw current and full load current is small (7/6), as i know that factor is 3/1.( In my country, there used 220V for line voltage and 380V for phase voltage). The same question for 3 phase motor.

Apr 15, 2014

What is the difference between line and phase?

• Ganesh Kaneriya
Jul 18, 2014

line to line voltage means voltage between 2 line
and Phase voltage means voltage between 1 line and neutral

92. neeraj kumar
Apr 06, 2014

thanks 4 d info it was really
help full we all must share
these things so we could get best of
knowledge

93. Joe C.
Dec 25, 2013

Please get in touch with me at [email protected]
Thanks

94. Annu
Oct 28, 2013

Thanks Dear sharing Such valuable data

95. nmr
Oct 03, 2013

sirs, for aluminium cables and wires current carrying was not indicated in the thumb rules.

96. aakifnouman
Sep 02, 2013

Thank You For This and for those u cant understand this is only a thumb rule just to understand and remember

97. sumitfloyd
Sep 02, 2013

On the section current capacity of Equipments, it is written
# 1 Phase Motor draws Current = 7Amp per HP.
# 3 Phase Motor draws Current = 1.25Amp per HP.

I am not quite clear on these points. Please clarify. Does it mean if we have 3HP single phase motor then it will draw 21Amp current throughout its operation or during its starting?

98. kriloter
Aug 28, 2013

These rules could be a little bit tricky unless you don’t know further connections …
Not all of them are aplicable in a different distribution systems worldwide, especially constants like •Current Rating of Transformer = KVA x 1.4, etc.
I suggest author should notice the conditions and input values in which are these rules aplicable and users should modify them according to a specific distribution system.

• alam
Mar 14, 2014

well said mate.!

99. shaijal100
Aug 24, 2013

pls tell me the difference between wire and cable.You mentioned different capacity for cu wire and a cable. You mean cable with aluminium conductor or something else..?Pls tell me..

• kriloter
Aug 28, 2013

cable is bunch of wires :-)

100. manjunatha_pm
Aug 24, 2013

Please give me the solution for below mentioned problem..
Actually in our plant we having two 500 kva DG set and One dg is new one and other one is old …efficiency is different, so when switch on both and synchronizing.. some problem is occurring and i am not able to synchronizing. .. please give any solution for this problem
my mail id is [email protected]

• srinivas subramani
Nov 19, 2013

Dear friend, just find the settings configuration in PCC2100 relay for parameter settings:)

101. ChAliGhafoor
Aug 23, 2013

kindly inform frm where did u get this useful information?