Hi SPR, with nearly 100 and views and no posts maybe a bit more info as to the layout, size, clearances, reasons why etc etc might provoke a response, you don't give us much to go on? Stu

I have been asked by a Moderator to explain my post. DNO = Distribution Network Operator, this is the private profit making company that owns and runs the local electrical distribution network, all of the LV stuff and some of the HV stuff will be owned & run by them. There are several of them around the UK, possibly one of the largest is WPD. Your DNO is not necessarily the company who you buy your electricity off. LV = Low Voltage, > 50V a.c. or 120V (ripple free) d.c. and < 1000V a.c. or 750 V d.c. between conductors, or 600V a.c. or 900V d.c. between conductors and earth. HV = High Voltage, > LV NG = National Grid, the private profit making organisation that owns and maintains the major electrical infrastructure (i.e. the National Grid). ESQCR = Electricity Safety Quality and Continuity Regulations 2002, as amended. SAP = Senior Authorised Person. This person will be qualified and competent to run and manage the HV infrastructure on your premises if you own such an infrastructure. They should be your first port of call when you have queries about the HV system that you own. You may have more than one, and there may be levels of Seniority. They will be competent and authorised to make HV switching changes, and sign off HV systems as safe etc. 11kV = 11,000V a.c. Sub = Sub-station. “Generally” an enclosure, housing, compound or other controlled access assembly of electrical equipment again “generally” housing a transformer where incoming HV transmission lines are split up into lower voltage out-going lines, which may still be HV or may be LV depending on the details. There are other uses and this is a very sweeping generalisation to be honest. Owned by NG, the DNO, or if you have your own on site HV distribution then owned by your organisation. The owner would generally be responsible for the maintenance & safety.