Welcome to the Ellis cleat calculator. This tool has been designed to aid in the selection of cable cleats. For any further advice or for a quote please contact us, we are happy to help!

This calculator is designed to provide correctly specified cleat spacings with respect to short circuit conditions. The calculator considers; cable formation, cable size, short circuit current and the installation environment. Further detail on the calculator and other factors that effect cable spacing is provided below the calculator.

The questions asked in this calculator are designed to provide Ellis with the proper information to specify the correct cable cleat for your project. The questions consider cable formation, cable size, short circuit forces and the installation environment only. It should be noted that issues such as cable weight for vertical cable runs, thermo-mechanical forces, extreme environmental conditions (e.g. extreme temperatures, industrial pollutants etc.) and any other non-standard cable installation factors have not been considered. Ellis should be made aware of these issues should they be present for your project.

Peak vs RMS Current

The formula uses peak current, however this is often unavailable with a Root Mean Square (RMS) value given instead. To calculate the peak current from the RMS, IEC 61439-1 Low voltage switchgear and controlgear assemblies is commonly referred to, which uses the following multiples:

10kA < I ≤ 20kA             Multiply by 2

20kA < I ≤ 50kA            Multiply by 2.1

50kA < I                         Multiply by 2.2

Intermediate Straps

The use of intermediate straps are not considered within the calculator. The below table details the straps suitable for each cleat whereby the cleat to strap spacing is the same as the calculated cleat spacing.

FLEXI-STRAP (SD) and PROTECT: VULCAN+, VULCAN+ QUAD, TRIDENT, ALPHA, VARI-CLEAT
FLEXI-STRAP (HD): EMPEROR, COLOSSUS

Fixed Interval Spacing

For fixed interval spacing applications such as cable ladder, the calculated cleat spacing should be rounded down to the closest possible interval. In the example of standard cable ladder which provides a cleat mounting surface every 300mm, should the calculated spacing be 0.8m the spacing to suit cable ladder should be rounded down to 0.6m.

Calculation Assumptions

1. A multiplication factor of 2.2 has been used to convert RMS to peak (based on IEC 61439-1).
2. Spacings given may only be suitable for a category 1 short circuit for certain products. Refer to Ellis to confirm whether category 2 criteria can be applied to the product spacing calculation provided.
3. Spacings for No Bolts Cleat assume a worst case scenario of a stacked formation. Larger spacings can be achieved if the cleat is fastened separately, refer to Ellis for more details.
4. Spacings for the 2F+ clamp assume the strength throughout the range is consistent. In reality it changes considerably and larger spacings may be achievable for larger cleats as the lowest strength has been assumed in this calculator.
5. Ellis have strived to ensure that the results generated by the calculator are accurate and correct at the time of use, it is however recommended to contact Ellis to confirm the calculated spacing is suitable prior to order placement. All calculated spacings are based on the results of short circuit testing to IEC 61914.

Read the full story about the Ellis cable cleat calculator here.