Evaluation Of Conduit Size And Fill Ratio
Once you choose to do the conduit installation method, you need to have a good understanding of how to select an appropriate conduit with required fill. A conduit is the hollow structure made from PVC material which houses a cable at the installation position. Even when doing conduit installation there is a lot of care which need to be observed. Things which may cause mechanical damages to the cable need to be avoided, the number of cable turns and its run length should be regulated. One has to minimize the bend radii of the cables, optimum sidewall pressure should be applied so that the maximum pulling tension in the cable doesn’t become destructive. The fill ratio is the hollowness of a conduit.
Life of a cable relies a lot on the condition of the conduit. The size of the cable will affect which type of conduit to use during installation. Besides, there are other factors which help to evaluate which conduit size is appropriate for a particular function. Below, the factors are discussed:
- Cable configuration
How the cables are configured should give you a guide on what size of conduit to choose. There are three configurations: single, triangular and complex configurations. A single configuration has one cable, that is to mean it requires a little smaller conduit compared to triangular which has three or complex which has four cables.
There are instances when cables are twisted together to form cross overs or when they go around bends. At such cases the cables form what is called a jam. The parameters which affect the jam ratio are the conduit inside diameter and the cables outer diameter. This means that the amount of jam in your conduit will determine its size.
Clearance is the difference in length from the inner part of the conduit to the uppermost part of a cable inside the conduit. A conduit which has more clearance has a wider space between the cable and the conduit. More clearance is appropriate for installations which has more bends or where large cables are to be used. Knowing which type of clearance you need for your installation guides you on the choice of your conduit size.
- Rigidity of the cable
How flexible your cable is will also be a determinant for the conduit size. Cables which are resistant to turning need larger conduits to create room for bending and reduce its chances of resisting the pulling force.
- Required fill
The conduit fill is the total space in a conduit that is occupied by cable(s). Having the knowledge of percentage fill of a cable helps to evaluate the size of a conduit to use. It is therefore recommended that you find out from the manufacturer’s data about the cable fills. Do in-depth consultation on the industrial standards and the relevant codes applied.
Conduits are as important as the cables themselves, they come in different sizes, different features and adaptabilities. It is your task therefore to know particular features of a conduit which will give you the service you need. Always evaluate.
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