Power cable Selection

Hello Ehidek,

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i need some one to assist me in getting to know the power cable selection methods through calculation by specifying some known parameters.

The current issue of the "Wiring Regulations", published by the Institution of Electrical Engineers, is a very good place to start.

Hi chaterpilar,

I endorse your view 100 % and consider it a good answer and I record it also.

Regards

Dear Sir

Good job done ! I endorse your views.

Hello ehidek,

The following is an answer I gave for a similar thread in the same forum. If you would have searched you could have read it.Please do a little effort and follow what is advised by other members.

"

Selection of Cable

The selection of suitable cable for any electrical system is the basic job of electrical engineer and a qualifying requirement for carrying out electrical job as per any safety standards. This type of thread is often seen in CR4 and I feel either the people putting up the thread are with out basic technical knowledge or people want a simple answer to attend an interview question. The proper answer to a cable selection or bus bar selection is so elaborate that it needs a minimum of one week's refresher course. Designing any electrical distribution network and electrical switchboard panel is real technical job and not amateur's job as it involves safety of the people operating the system and equipments. Providing a simple formula or calculated figure is improper as the value depend on various parameters. A basic parameters for selection of cable and factors to be considered are listed below .

1. The cable should be rated for the correct voltage rating and size of conductor.
2. The selection of normal current rating will depend on temperature rise on normal conditions. This will depend on :-

(i) The ambient temperature of the location where the cable is laid .

(ii) The type of laying of the cable viz. underground, on cable tray, in air ,in duct etc. each condition has its own de rating factors.

(iii) The type of cable XLPE, PVC, PILC, FRLS etc and material of conductor (Copper, Aluminum). Armored, unarmored

(iv) The type of industry and load chemical, engineering, fixed load , varying load,

(v) The length of cable and depth of lying

(vi) System of back up protection and tripping time delay.

3. Short circuit rating of the conductor

The principle involved here is that the cable selected should withstand the short circuit current with out temperature rise or damage till the time the protective device like fuse ,MCB, MCCB , ACB , OCB, VCB etc. operate to disconnect the faulty system from the mains.

In India we follow the recommendation of IS 3691-1967 Part I, III, III, IV, and V Similar standards are followed in all countries which will provide the required data to select the cable."