Loose Cable

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How much Loose Cable do I need for my installation?

This is quite simple but very important. All the cable must be used on the floor and cannot be cut, crossed over or bunched together.

The process below is exactly the same for both the 10W/m loose cable and our 17W/m loose cable.

Firstly work out the total free area where you will be applying the heat. If the cable is to be placed in between joists please minus off the thickness of the joists to ensure an accurate calculation.

Allow a 50mm minimum gap around the perimeter of the room.

How much will I need in a bathroom?

Please see example above.

The free area is 5m² but now we must deduct the area occupied by the unheated gap around the perimeter – let’s call it 0.5m².

The area to work with is 5 – 0.5 = 4.5m².

To calculate the cable spacing multiply the area to work with by 1000 and divide by the cable length.

This installation would suit our 10Cable60 – a 60 metre cable rated at 10W/m and total loading of 600 Watts.

4.5 x 1000 / 60 = 75mm spacing.

How much will I need in a kitchen?

First measure the length and width of the room in meters. An average kitchen is approximately 3m x 4m. Multiply these together, which gives a total of 12m²

Now it is necessary to remove from this total any Kitchen units or other fixed items of furniture that may block the heat. A normal Kitchen unit is 0.6m wide. If the units were along 3m of wall, this would be 0.6m x 3m = 1.8m²

Saying this unit is the only Kitchen furniture in the room, remove this figure from the total room area. 12m² - 1.8m² = 10.2m²

The free area is 10.2m², but now you need to deduct 0.5m² from the edge of the room for the unheated gap – let’s call it 0.3m²

The area to be heated is now 10.2m² - 0.3m² = 9.9m²

To calculate the cable spacing multiply the area to work with by 1000 and divide by the cable length.

For primary heat, this installation would suit our 10Cable40, and 10Cable150 – 40 & 150 metre cables rated at 10W/m and together giving a total loading of 1900 watts.

9.9m² x 1000 / 190 = 52.1mm spacing.

This spacing is important and the installation loading can be estimated from the table provided. Should your calculations arrive at less than 50mm for the 10Watt cable, or 84mm for the 17Watt in screed cable then the cable size is too large, and you should select a different cable size.