U.V Resistance of Plastic Enclosures
emf would like to warn our customers after enquiries regarding the UV resistance of ABS compared to Polycarbonate.
It is evident when we are asked to replace an ABS enclosure, that this material will not stand up to the harsh UV rays in New Zealand. We have always, and will continue to, recommend Polycarbonate as the best enclosure material to use when installing an enclosure that will be exposed to the elements.
International companies often market ABS as having “excellent UV resistance, ideal for exterior installations” which simply isn’t reflected in their performance in NZ’s sunlight. This has led to many disappointing enclosure failures and deterioration across Australasia. The reason for this is twofold.
Firstly; Many European manufacturers of enclosures think of the Mediterranean as their benchmark for UV levels worldwide. The average Mediterranean UV index over the course of a year is 4-5, compared to 7 – 10 in Australia and New Zealand (Peaking at 12-13 in the summer months).
Secondly; There is the added complexity that solar radiation consists of visible light and thermal radiation, in addition to UV radiation. In fact, less than 10% of all solar radiation is UV, but it is the most significant factor in fading and mechanical weathering. However, other effects of solar radiation are left out from bare UV tests, so even when testing is completed it often doesn’t provide an accurate representation of ‘real-life’ conditions.
There are three scientific reasons why the sun in the Southern Hemisphere is so strong.
- There is less ozone here to block UV rays.
- Earth's orbit takes us closer to the sun during our summer than during the northern summer.
- We have less pollution, or solid particles, in the air that help to deflect UV rays.
This extra strength in the sun has been widely proven to destroy plastics in the southern hemisphere much faster than they would in the north, and this is something that electricians and specifiers need to be aware of when choosing enclosures for demanding environments.
For more information regarding this please read our industry insight on the differences between plastics and our case study on Polycarbonate use in the Hawkes Bay.