CABLE TIES VS CLEATS more steel in a cleat than a tie . Therefore , in order to make a direct comparison you need to consider the cross sectional area of the material being used – a calculation based on width , thickness and the number of times it is wrapped round the cables .
Cable ties are typically less than 20mm wide and less than 0.4mm thick and so have a cross sectional area of less than 8mm 2 . If the strap is wrapped round twice we have material with a maximum cross sectional area of 16mm 2 securing the cables . In comparison , a top of the range stainless steel cleat will have a cross sectional area of 100mm 2 .
Harking back to simple physics , the ultimate tensile strength of a material is proportional to its cross sectional area . Therefore , using the information above , and all relevant supporting short circuit test data , if the calculated fault level for a system required the installation of a top of the range cleat every 300mm , it would be unlikely if the cost of the equivalent appropriate number of cable ties was less than the cost of the cleats . And that ’ s before you even take into account the time it would take to install them all .
• The cable tie can be fed through perforations on the ladder rung if they are present .
Of these three methods , both option one and option three introduce significant variables that will have an impact on likely performance during a fault . In both cases a foreign body is being introduced to the loop that contains the cable . As such everything from ladder material to rung profile ; types of hole and sharpness of edges ; and even surface finish and cable diameter can have an impact on the whole arrangement . As such , it ’ s impossible to say that the result of a short-circuit test on a stainless steel cable tie is transferrable to the real world , unless the installation is identical to the testing set-up .
Of course , installation option two is more likely to deliver real life performance that matches short-circuit testing performance for a cable tie . But in this scenario both the cost of the parts required , and the installation time will increase significantly , making it even less competitive when the number of ties to cleats ratio is taken into account .
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THE PRIMARY CONCERN FOR ALL THOSE INVOLVED IN ELECTRICAL CABLE INSTALLATIONS SHOULD BE SAFETY .
Short-circuit testing
The final point to address is short-circuit testing , and in particular the question of whether the data gathered from a test is transferable to a real life installation ?
As far as cable cleats are concerned , the answer is usually yes . This is because , under fault conditions , a cable cleat constrains all the forces generated between the cables . The mounting structure has no influence on the cleat ’ s performance and so it should perform at the level indicated on the short-circuit test certificate .
The situation is nowhere near as cut and dried when it comes to stainless steel cable ties – mainly because of the difference in fixing methods . Typically there are three ways in which a cable tie is used to attach cable to ladder :
• The cable tie can be wrapped around both the cable and the rung .
• The cable tie can be installed using a mounting bracket , which fixes to the rung .
The final decision
What needs to be remembered when considering the respective merits of both stainless steel cable cleats and cable ties is that the primary concern for all those involved in electrical cable installations should be safety .
In order for an electrical installation to be deemed safe , cables need to be restrained in a manner that can withstand the forces they generate , including those generated during a short-circuit .
Yes , both cable ties and cable cleats have their place in the specification picture . And yes , there is a minimal amount of overlap where it is feasible that an installer or specifier could choose one over the other . But it is minimal , and the specification decision shouldn ’ t be made based on misleading claims aimed squarely at undermining the sales of a tried , tested and trusted solution .
Cables need to be restrained in a manner that can withstand the forces they generate .
Cable ties are typically less than 20mm wide and less than 0.4mm thick .
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