This Q & A of the Day is about surge protection devices (SPDs) and their correct installation for solar PV systems. It is answered by SELECT (Theme - Power):
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Question: I've recently been working in South Australia and I've come across surge protection devices for the first time, but I've also seen various ways in which they have been installed:
1) Directly off the load side of the main switch with 6mm via a 32A MCB, then off the load side into surge protection, then off the surge protection unit onto the earth bar with a 6mm earth cable.
2) Directly off the main switch on to surge protection then on to an earth bar.
In a standard installation in South Australia, typically, there is a 6mm earth onto an earth stake.
Now that I'm back in the UK and solar PV is picking up, what is the correct way in which SPDs should be installed, please?
Answer: As this is a fairly new concept in BS 7671:2008, I recommend that you contact the equipment manufacturer for guidance.
However, the most common method in Britain appears to be connecting the surge protection device (SPD) via a three-phase circuit breaker with the SPD in an adjacent enclosure.
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