Posted By George Wedgwood David, a lot depend on the type of switchgear contained and on the prospective fault levels of the installation. Clearly, if oil filled switchgear were used it could pose a significant risk in close proximity to public access. However, it will be more likely as it will be a new sub, that the gear if SF6 filled and reasonable safe unless entry is required to the sub. The type of containment is also important as some new fibreglass containers are little resistance to an explosive failure - but these subs are inherently reliable in the main as probabilistic analysis of historic failures does not show a significant problem. However, if the sub is large and contains oil-filled insulators for example, make sure you stay well away! These can explode violently with little notice and fragments can travel in excess of 50 metres! Even cable joint boxes (found in mopst subs) can explode violently if moisture find its way in. So all in all, you would be best to find a 'quiet corner' to site this in, with a minimum of 10 metre space from public access all the way round it, to be safe. It really needs a technical risk assessment to quantify the detail and the Regional Electricity Company involved should be asked to provide this. It should include security and containment and well as explosion venting details. I hope this helps a bit. Regards, George Wedgwood FIOSH RSP