Until recently we had never had an issue with rats damaging our fibres in our many underground ducts. Over the last few years we have been installing CST armoured fibres because other people have had problems with rodents and also we judged that CST would probably be enough to stop new cables sawing through existing ones when they were drawn in - a problem we have had. Just recently we have had two cases of rat damage with a number of fibres being cut. These were older, unarmoured duct grade cables. Our two pronged plan was to pull in replacement CST armoured cables and try and control the rats. When talking to the rodent control chap though, I got a bit of a surprise. He said that the rats would prefer to gnaw on the armoured cable and would easily cut through the CST armour. Does anyone have any real-world experience of this? Should we be installing SWA armoured? Are there any other actions we should be considering? The rodent control chap suggested sealing up the ends of the ducts in each chamber, not to stop the rats, but to allow us to track them so that we can find where they are getting in to the network.
Might be worth talking to your cable vendor. We were a Brand-Rex shop, and I seem to remember (this was a good while ago):
Basic rodent protection is a glassfibre incorporated in the sheath which rodents find unpleasant to chew. Second stage was CST followed by SWA.
My thoughts: Even CST is considerably more expensive to install, and also have a general preference to not have metallic sheaths on cables if it can be avoided. I wouldn’t want to be going up to SWA as it becomes quite unmanageable.
I think you’re doing alright with CST… others have suggested adding innerduct as extra protection - will fill up those ducts quickly tho!
Will
