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Posted By Topic: Unprotected tps

Nov 22 2013 12:22

Can you run a tps cable outside unprotected? For example run a feed to a garage from the roof of the house to the garage on a continary wire not in conduit? Is there a reg saying you can\'t because white tps is not u.v protected? I spoke with an inspector who said it was fine as long as it was high enough but my boss thinks its illegal?

Nov 22 2013 16:28

As always, when anyone says \"you can\'t\"; ask \"why not?\"... and don\'t accept anything less than a specific rule as an answer.

Protection of cables has to be adequate for the particular circumstances. In many cases, TPS is perfectly OK on catenary, and there are conductor ratings in the Tables of AS/NZS 3008 for installation condition exposed to direct sun.

Nov 22 2013 19:28

Thanks for the reply, I have had a look and cant find the table or anything that says it is ok? Any chance you have page number of table @AlecK

Nov 23 2013 17:06

3.5.8 Effect of direct sunlight Current-carrying capacities are given in Tables 15, 20 and 21 for flexible cables and aerial cables exposed to direct sunlight. For other types of cable installed in locations exposed to direct solar radiation it will be necessary to make some provision for the effects of the increased heating. This may be achieved by one of the following means:
(a) Provision of a shield, screen or enclosure which allows for the natural ventilation of the cable.
(b) Reduction of the current-carrying capacity of the cable by an appropriate amount in accordance with the higher air temperature. As a rule-of-thumb alternative to any recommendation from a cable manufacturer, a correction factor obtained from Table 27(1) for a temperature 20°C higher than the ambient air temperature may be applied.
NOTE: For further information on the effects of ultraviolet radiation it is recommended that the cable manufacturer be consulted.

Nov 24 2013 10:32

I\'ve seen TPS that was clipped to the top of a fence that was exposed right down to the bare conductors. Even though modern TPS may have better construction than older TPS, I believe TPS should be protected from UV damage.

Nov 24 2013 13:22

is normal white or circular black TPS UV stable probably not but should state yes or no in Sdocs? think circular is PVC coated on small sizes and certain PVC,c are uv stable but normally would be indicated somewhere......if not then should be protected from NZ,s vicious UV rays and enclosed