Installing Ethernet cable outdoors

[#1]

Not a cry for help but advice for those who install Ethernet cable. Experience doesn't come cheap, so maybe this might be useful to some-one.

I purchased some purple sheathed CAT 5e cable years ago with an unspecified sheath, but assume it was low density polyethylene. This cable is excellent indoors as it is very flexible and is giving faultless service.

Then the learning: I installed a length at a friends house externally on a south facing wall, so it was getting full sunlight.

The following photos show the effect after about 3/4 years. The outer jacket has rotted away, leaving the inner cores exposed. These obviously use different insulation and the electrical connection was unaffected.

Lesson learnt: If you are running cables externally, use external grade cable.

[#2]

Use trunking, especially if exposed to sun!

I've run various cables round the outside of my house over the years. The degradation of old-school BT cables in the sun (when we had wired phone extensions) was something to behold.

Oddly I've found that standard grey ring-main mains cable (NOT used for power!) last for decades without any protection. I use it for hifi speaker extension wiring in case you wondered. 🤣 It's really good for that, 3 cores for Left, Right and common ground and pretty low resistance.

[#3]

I now understand that mains cable insulation is PVC with anti UV additives. Standard Ethernet and flexible data cables use low density PE. External cable is medium density PE (which is why it’s stiffer) with anti UV additives.

[#4]

LDPE is susceptable to degradation with extensive exposure to UV.

[#5]

@grumble 

I’m fully aware of that, now!

The problem is that when you buy Ethernet cable the jacket material is rarely specified. I wrongly assumed that the only difference between standard and exterior grade cable would be the thickness of the jacket.

The message I am trying to put across to anyone following advice to fit external Ethernet cable is: Either use exterior grade cable or fit a duct, ensuring that no part of standard cable is exposed to direct sunlight.

[#6]

I’ve got an Ethernet cable down to my garage at the far end of the garden using exterior grade. Part clipped just as it comes to the house wall in full sun and part a mixture of buried, under the shed and clipped to the fence inside some 15mm hosepipe for extra physical protection. It’s been there well over 30 years now and still copes fine with 1Gb even though I rather incorrectly use all the pairs to carry 2 links (one for a wifi extender). Even the mice haven’t bothered it though they had a go at the garage wiring in pre-cat days! The right stuff lasts a long time.