Good question - but I suppose that it nearly always is black, and I'm not even certain how UV resistant it is.
Kind Regards, John
suspended cable to Detached garage
- Thread starter billm
- Start date
Kind Regards, John
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I just asked a cable shop on eBay and he said SWA is not UV resistant and I should use H07RN-f Rubber cable which I think is the sample I posted a photo of earlier.
So it appears my options are I can either have SWA, with shielded earth protection but is not UV resistant or Rubber cable which is UV resistant but does not have earth shielding !
So, SWA is not an option, then.
Use the rubber and resist the urge to hit it with a spade.
First off the cable should be black, despite the experiments we've been watching, as black is the most UV resistant colour.
BT for example: anything exclusively underground tends to be natural polyethelene, anything expected to be in the sun (aerial cable, clipped to a poleor building etc) has carbon added to the poly, making it black. The white internal cable we see in our houses always had a maximum length to be used outdoors in BT rules.
The silver cable you were shown does sound like SY and is totally unsuitable... The outer sheath will turn yellow/brown very quickly in the sun (Probably start showing in a few days in the sort of weather of the last week) and it will give the appearence of going rusty, depending on - presumably manufacturer - it will either go extremely brittle and crack or go very soft and sticky. If I encountered SY cable used for such a span I'd consider grey T&E to be a significant upgrade !
BT for example: anything exclusively underground tends to be natural polyethelene, anything expected to be in the sun (aerial cable, clipped to a poleor building etc) has carbon added to the poly, making it black. The white internal cable we see in our houses always had a maximum length to be used outdoors in BT rules.
The silver cable you were shown does sound like SY and is totally unsuitable... The outer sheath will turn yellow/brown very quickly in the sun (Probably start showing in a few days in the sort of weather of the last week) and it will give the appearence of going rusty, depending on - presumably manufacturer - it will either go extremely brittle and crack or go very soft and sticky. If I encountered SY cable used for such a span I'd consider grey T&E to be a significant upgrade !
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Eland disagree.
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Thanks - as I said, I didn't know whether or not the sheath of SWA is UV-resistant/stable.
However, that doesn't alter the fact that the sheath is nearly always black (fairly matt black, at that). Considering what I observed in my (very short-term (until the sun became hazy) experiment with black conduit on Tuesday, I imagine that similarly-exposed black SWA would probably have reached well over 60°C after a while - and if one wanted to design with that possibility in mind, a quite substantial de-rating would be necessary.
Kind Regards, John
If its XLPE-insulated, then yes, but so what?
Looking at the maths/physics simplistically, if the ambient temp (i.e. temp of conductors with no current flowing) is 30°C, then that means that the CCC will be that current required to raise the conductor temp by 60°C (taking it to the max of 90°C). If the ambient temp is, as I was suggesting, more than 60°C, that means that less than 30°C temp rise due to current can occur (before one hits the 90°C limit) which, in simplistic terms, means that the CCC would be less than half of what it would be with an ambient temp of 30°C.
We were initially talking about (probably "70°C") PVC-insulated T+E, in which case the situation would be much more dramatic. If the ambient temp (temp of conductors with no current flowing) were >60°C, then the amount of current which could flow through the cable before conductor temp reached 70°C (i.e. "the CCC") would be very small.
Kind Regards, John
Best option is a leather strap. Tie wraps in sunlight become brittle and can snap in wind weather
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Catenary Cable Suspenders
Cable Suspenders are manufactured in leather with a hot dipped galvanised mild steel hook and brass eyelet. Used to support cables on catenary wire system.<br/> **Standards:** BS EN ISO 1461<br/> **Ma
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