Electrical conductors are made of different material. Cooper and Aluminum conductors are the most used in electrical industries. properties of each cable depends on the material it made of. Cables ampacity is one of the important properties electrical engineers and electricians should know.
What exactly is cable ampacity?
Current passing through a cable faces electrcal resistance, and then produces heat. The temperature of the conductor and the insulation around it rises depending on the current value. Here comes the cable ampacity.
Cable ampacity or current carrying capacity is the maximum current that the cable can carry continuously at maximum operating temperature.
Where to find table of ampacity for cables?
Each cables manufacturer has products catalog. This catalog contains data and tables of the cable electrical and physical properties. Voltage drop, Derating factors, short circuit, table of ampacity and more electrical data are in these tables.
One of the most important tables that every one who works with cables needs it regularly is the ampacity or current carrying capacity tables. The table contains current values that every cable can carry.
In the table above we find cable cross section area, in the firs column then resistance and current that each cable size can carry. There are three current values for each cable size. This is because this current value affected by the laying method. Laying the cable in ground, in free air or in duct these are the three methods in the table.
What affects cable ampacity
As mentioned above, Cable laying method is one of some factors which affect current carrying capacity of the cable, Other factors are listed below:
- Conductor material.
- Insulation around the cable. i.e XLPE or PVC. XLPE insulated cables can carry more current than PVC insulated ones.
- Laying method of the cable. i.e in air, underground or in duct.
- Laying in Trefoil or flat formation.
- Temperature of the ambient air.
- Soil thermal resistivity.
- Burial depth underground.
- Duct inner diameter for cables in duct.
- Number of cables in the same laying path.
Cables data, Android app for electricians
Cables tables are used in designing offices and in work site as well. So its important to have cable rating tables on your hands. electrical4uonline engineer advice using CABLE TABLE android app. This app has cables tables and data, like ampacity , Voltage drop, derating and short circuit tables.
The app is 100% free. But it has Ads free paid version, you can switch to it later.
