Current Carrying Capacity of Copper Cables

MAKE A HABIT OF CHECKING EARLIER THREADS.

Craig one more for you .

well, just joined the forum today, checked earlier threads and then put the comment. Being from electronic background, I am nervous hearing different opinions, not that the max current can't be calculated by "Standard Formulae" thought, why to re-invent the wheel.

Go to the RHS- on the box search this forum, type in your query

it wil take app 63A current at a temp of 60 degree

Ability to handle current is the function of application directly, A wire of given cross section can handle much larger current in open air and very low in a thermally insulated area.

for use inside a machine and transformer its normally taken as 3.0 Amps/sq*mm, But as your post say its a cable it should be able to handle 8 to 12Amps/ sq*mm. again depending on surrounding.

Generally when we multiply the given mm.sq with 1.5 it gives us the current carrying capability of the cable, it can varies where u lying the cable on the temperature and location of the cable.

May be you are a space rocket/shuttle designer.

Ashutoshd,

The various answers given already are all "rules of thumb" and valid within the assumptions they are based on for approximate cable size, environment, etc. Unfortunately, all such rules fail if they are applied over a wide range of cable sizes or environments for two basic reasons:

1. As cable size increases or AC frequency increases, more and more of the current is carried on the surface of the conductor -- the so-called "skin effect" -- so AC current carrying capacity begins to more closely correspond with diameter instead of area. This generally gets quite noticeable for cables exceeding 300 mm² and is usually negligible for cables smaller than 10 mm².
2. The applied current heats the cable because of its resistance, so thermal limits imposed by insulation types and environmental conditions can significantly restrict the safe current carrying capacity.

As time passes, you will appreciate more and more how inter-related everything can be.

--JMM

A 16 sq mm cable will carry a current of approx 84 amps. This is dependent on how many cables are running with the subject and the insulation type.

Any good cable manufacturer hand book will give current carrying capacity tables.

But can anybody give the exact formula to calculate the current carrying capacity of any cable having a certain dia except these assumptions??

No formula can be applied, Its subject to what standard you follow,

Just like our clothing,How much we want to cover and expose depends on what we follow.

Hi manzoor,

You can refer to IEE regulations for the standards. However, factors like installation mode, environmental conditions, insulation type, voltage drop limitation and cable materials can make variance to the tabulated values.

For more details on cable sizing theory, send me your email to send you a pdf document.

Regards

Mr.

This is faisal. As i m an electrical engineering student, can u plz send me the table containg current carrying capacity of different conductors & related information and calculation in sizing the conductors and ofcouse thevoltage drop calculation also. On the whole i want to know every information on cables before lying them in conduit.

Thanking you.

faisal.

hi, i am new user for this site and please send the pdf document. my email id is gsundaram@essar.com

regards

sundaram

cupidonly@gmail.com.... this my mail id send me the relevant documents

plz send me cable ratings chat my fmcool75@yahoo.com

what is the standered chart

Slightly less than you need it to carry. Rule of thumb, no matter how little current your application requires, the cable you have on hand is one size too small...

Current carrying capacity of conductors as listed in the National Electrical Code (USA) is figured using an area called: circular mils. It is computed by measuring the diameter of the cable and squaring. Note: 1 inch is equal to 1000 mils. Example: a cable measuring 1/4 inch in diameter would be equal to 250 mils. 250 mils x 250 mils = 62,500 circular mils. Table 8 in chapter 9 of the NEC lists this between a #3 & #2, so you would use the ampacity table for a #3 (smallest). Table 310.16 lists #3 in the 60c column as 85 amps @ 60hz for 3 conductors in a raceway with an ambient temperature of 30c. Higher frequency can mean using larger cables. In free air #3 copper is 120 amps with an ambient temperature of 30c. You have a cable 16 sq mm. Converting to circular mils may be tough. A millimeter is equal to .03937 inches. Remember you need to find the diameter of our cable to use the formulas.

Hi, all

Try this : http://www.trinitycables.co.uk/tech-data4.asp

They quote several examples.

Also do not forget voltage drop per metre of cable at required current,

if it is a short run then it will not be critical but long runs can be.

You can also find all you need from the tables of the IEE Regs 17th edition.

these will give you metric cable sizes.

HELLO

1/ App.82A for normal outdoor PVC sheathed cables applications.

2/ Any cable maker company data sheet give you your demand.

REGARDS

How much AC current a 16 Sq. MM copper cable will carry? Is there any thumb to approximate CS VS. Current Carry capacity

Ans: 1mm sq. cross section area of copper can carry 6 amp of current. in case the cable is made of multi strands then the de-rating has to be applied based on diameter of each strand and no of strand.

Bundle of strand are 2~5, 6~15 and 16~30 then de-rating factor (X amps)to be applied 0.8X, 0.7X and 0.5X respectively

regards,

Hemant