ZIP WIRE CABLE DIAMETERS EXPLAINED
One of the most common questions we are asked is "What is the correct cable diameter for a zip wire?"
At ZipWireShop we supply cable diameters which far exceed the safety parameters stated by cable manufacturers.
These safety parameters are somewhat complex but..
The short answer is:
- 6mm diameter is suitable for cable up to 40m in length
- 8mm diameter is suitable for cable from 50m to 60m in length
- 10mm diameter is suitable for cable 70m+
These are the cable diameters that all of our garden (domestic) zip wire kits are based upon.
We only use 7x19 strand galvanised cable which is the ideal specification for zip wire use.
BEWARE: Some zip wire retailers will try to "up-sell" to a cable diameter which is thicker than required by scaremongering you into spending more money with them than is necessary. This is not only a waste of money but also makes the cable harder to tension due to the unnecessary additional weight.
The long answer is based on the Safe Working Load (SWL) of the cable, the weight of the cable plus the weight of the heaviest person who will be using the zip wire.
Safe Working Loads explained:
The Safe Woking Load is usually based on a 10:1 ratio of the Minimum Breaking Load (MBL). The Minimum Breaking Load is the point where the manufacturer states the cable may be at risk of breaking under load. Therefore, it would take 10 times the Safe Working Load for the cable to reach the point where it may be at risk of breaking.
The other thing to consider is that the Minimum Breaking Load is reduced by 20% at the cable clamp positions.
Safe Working Loads of our cables (allowing for 20% reduction of the Minimum Breaking Load):
- 6mm diameter cable has a SWL of 188kg (30 stone)
- 8mm diameter cable has a SWL of 335kg (53 stone)
- 10mm diameter cable has a SWL of 522kg (82 stone)
- The overall weight of a 40m (6mm) cable is 5.5kg.
Therefore, a 40m (6mm) cable can take a maximum rider weight of 28 stone to stay within the Safe Working Load
- The overall weight of a 60m (8mm) cable is 14.6kg.
Therefore, a 60m (8mm) cable can take a maximum rider weight of 50 stone to stay within the Safe Working Load
- The overall weight of a 100m (10mm) cable is 38.1kg.
Therefore, a 100m (10mm) cable can take a maximum rider weight of 76 stone to stay within the Safe Working Load