7 cable management mistakes to avoid | Automation.com

7 cable management mistakes to avoid

7 cable management mistakes to avoid

February 2012

To prevent unnecessary downtime, your cable management system must be correctly specified, designed, and installed.

Simple considerations in the beginning can prevent big problems - such as loss of continuity, insulation damage, mechanical deformation, or EMI problems - later on.

Nowadays, cable carriers can withstand longer travels, faster speeds, and heavier loads than ever before. Such advances in automation technology mean that rules of thumb, such as only filling up to 80% of a cable carrier’s cross section, have become outdated.

For this reason, we’ve put together seven common cable management mistakes and also detailed how you can avoid making them.

Cable management mistakes 

1. Lack of interior separation

Interior separators and shelves are crucial for keeping similar cables and hoses compartmentalized. When no separation is used, cables can cross over one another and become entangled.

The clearance height of a compartment with several cables and hoses next to one another shouldn’t amount to more than one-and-a-half times the largest cable or hose diameter.

Cables with very different diameters should be laid in separate compartments. Cables and hoses with incompatible outer jacket materials should also be separated. (See point number 6 below for more on this.)

The maximum cable or hose diameter corresponds to the inner height of the selected cable carrier, with additional minimum clearance. We recommend leaving a 10% clearance around round electrical cables and a 20% clearance around hydraulic hoses.
Correct cable separation

A correctly separated cable carrier

The faster and more frequently the cable carrier operates, the more important the exact positioning of the cables and hoses inside. For high-speed applications over 1.64 feet per second, or high-cycle applications over 10,000 per year, cables or hoses must not be laid on top of one another without horizontal separation.

2. Unevenly distributed weight

Cables and hoses need to be laid inside a cable carrier so that they can move freely from side to side, without exerting tensile force along the radius.

Unevenly distributed cable weight can result in a cable carrier that is too heavy on one side. This can disrupt movement and cause the cable carrier to tilt, potentially interfering with the work area.

3. Cable carrier overfilled

It’s easy to think, “I’ve got the space, why not fill it?”

However, overfilling a cable carrier can obstruct free cable movement. Cables that do not have room to move will interfere with the movement of the cable carrier.

In addition, if cables become caught on one another and bind together, cable jacket wear can be significantly increased.

There is also more chance of Electromagnetic Interference (EMI) when power cables and data cables are positioned close together.

As a rule, we recommend you space power and data cables as far apart as possible. This is best practice for EMI prevention.
Overfilled cable carrier

An overfilled cable carrier
 
4. Lack of proper strain relief

Without strain relief, you can’t control the length of the cable inside the carrier.

As the cable carrier moves back and forth, the cable will pull into the carrier and bunch up, causing premature system failure. Points outside the carrier, such as the connectors or end termination points, will also absorb all the mechanical force.

Typically, round electrical cables should be secured with strain relief at both ends. In exceptional cases, the cables may be fixed with strain relief at the moving end only.

A gap of 10-30 times the cable diameter between the end of the bend radius and the fixed point is recommended.
Strain relief

Strain relieved cables inside a cable carrier
 
5. Not installing cables along the neutral axis

Correctly strain relieved cables will position in the neutral axis of a cable carrier.

Cables should not be pulled tight against the inner radius or pushed up against the outer radius.

Strain relief should be performed and then checked in both the extended and home position.
Neutral axis

The cable is neither pulled tight against the inner bend radius, nor pushed against the outer radius.
 
6. Dissimilar jacket types placed next to one another

If cable or hose outer jackets have different coefficients of friction (COF) and they rub against one another, the harder, more resilient material will wear down the softer material.

While PUR and TPE outer jackets have similar wear characteristics, and so laying them inside the same compartment is generally not a problem, mixing PVC and PUR jackets is not recommended.

If jacket materials need to be mixed in the same carrier, then ensure the jacket material is rated for cable carrier use. Rubber or thermoset jacket materials tend to have tackier surfaces and will bind inside cable carriers. For this reason, we don't recommend them as an outer-jacket material.

7. Cable carrier length improperly calculated

If the length of the cable carrier is miscalculated, then the full range of movement may be compromised. Pulled or stretched cables can result in conductor breakage.

Here are some equations you should use to properly calculate the length of an igus® Energy Chain® cable carrier (see right).

If the fixed end is located in the center of travel, the cable carrier's length, "LK", is calculated by using half the length of travel and adding the value "K" for the bend radius. Placing the fixed end in the center of travel is the most cost-effective solution, because it requires the shortest cable carrier, cable and hose length.

Due to the wide variety of different applications out there, we highly recommend you take advantage of our free consultation services. Simply provide us with a list of your cable requirements and you’ll receive our recommendations by the end of the next business day.

About igus
igus® develops industry-leading Energy Chain® cable carriers, Chainflex® continuous-flex cables, iglide® plastic bushings, igubal® spherical bearings, and DryLin® linear bearings and linear guides. These seemingly unrelated products are linked together through a belief in making functionally advanced, yet affordable plastic components and assemblies. With plastic bearing experience since 1964, cable carrier experience since 1971 and continuous-flex cable since 1989, igus® provides the right solution from over 80,000 products available from stock. No minimum order required. For more information, contact igus at (800) 521-2747 or visit www.igus.com.

Author bio:
Don Nester - Chainflex® product manager
Don Nester has 12 years experience in the wire and cable industry, specializing in manufacturing, design and applications. Don joined igus® in 2002 as the product manager responsible for all aspects of the Chainflex® continuous-flex cable product line, including sales and product development.

 

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