Transformer bunding requirement?

[BIGEYE]

Under UK rules & regs, is there a requirement to bund fluid filled transformers to contain any insulating fluid leakage? This will be a new transformer installation and the fluid will be Midel. There are other transformers (oil filled) on site and these are not bunded.

TIA

[Besoeker]

Under UK rules & regs, is there a requirement to bund fluid filled transformers to contain any insulating fluid leakage? This will be a new transformer installation and the fluid will be Midel. There are other transformers (oil filled) on site and these are not bunded.

TIA
I can't say I have ever seen an outdoor ONAN transformer with a bund. Conversely, I can't recall seeing an indoor one without.

That's just my experience. It isn't my area so I don't know what the mandatory requirements are.

[wislum]

Hi,
Have just read your posting.
From BS7671-Jan2008 Part 4 Chapter 42 reg 421.5
Where electrical equipment in a single location contains flammable liquid in significant quantity,adequate precautions shall be taken to prevent the spread of liquid,flame and the products of combustion.
Note1 Examples of such precautions are:
a) a retention pit to collect any leakage of liquid and ensure extinction in the event of fire.
b)installation of the equipment in a chamber of adequate fire resistance and the provision of sills or other means of preventing burning liquid escaping.
Note2 Accepted lower limit for a significant quantity is 25 litres
Note3 For quantities of less than 25Litres it is sufficient to take precautions to prevent the escape of liquid.
Note4 Products of combustion of liquid are considered to be smoke and gas.

Therefore in order to comply with regs you should fit a bund. Older Tformers were probably fitted to previous edition of regs standards