cable size selection

Hello kumarnaik

This is a perennial question.

That means it keeps being asked repeatedly here at CR4 Forum.

Use the facility at right: "Search all of CR4", and enter the Search Terms.

Just to start you off, refer here: http://cr4.globalspec.com/thread/11833/power-cable-rating

I used the Search Terms: Cable Table

Trust that assists you.

If you need further help, reply here, with

Kind Regards....

Use a larger cable than the code requires and you will not starve the eqwuipment for power causeing overheating and lowering the usefull life of the equipment.

This is accounted for by derating properly

Sizing a cable is a bit more complicated than simply looking at a table or pulling up a formula. You have to consider the environment the cable sees, you have to consider the load characteristics, motor? computer? Incandescent lamps?... Hire an electrician you cheap SOB and get it done right.

Simple answer! Get a copy of the American "National electric Code'' and it will simplfy your requirements especially since it considers temperature restriction of the type of insulation used.

Please refer to the current edition of the Wiring Regulations, published and maintained by the IEEE.

There are numerous factors that need to be considered:

1. Feeder or branch circuit (different multipliers for derating)
2. ampacity required
3. copper or aluminum
4. ambient temp
5. free air or in a raceway
6. distance (to calculate voltage drop)

Yes, I'm a licensed Journeyman

I forgot. When all variables are calculated refer to Table 310 in the current Nat'l Elec. Code

Sorry wasn't logged in

When we select cable then we calculate these things.

1. Air temperature .

2. Load current ( how many load (current)on this Cable we used ).

3. cable capacity(all company allow cable maximum load capacity)

4. Voltage drop calculations:

5. Running voltage drop.

6. Distance (cable length)

7. cable laying ( under ground or open laying)

8. cable type ( 2 core , 3core,4 core).

these all things calculate then we laying a cable.

Note. All company give a chart where note cable maximun ampere capacity.

how to calulate voltage drop in cable?pls tel me the pormula

Hello again, kumarnaik

There is no single "Magic Formula", except Ohms Law, modified for the particular usage you intend..

There are many variables, as you have been advised above.

Consult the Maker of the cable you intend to use, and use that Maker's Cable charts for the actual type of cable you intend.

Those charts will advise you about deratings too.

Kind Regards....