I have a new external steel stair case 5 floors high being erected onto an existing building. The building itself is 6 floors high with very old lightning protection i.e. untested in decades. Do I bond this stair to the MET or consider seperate lightning protection or connect to existing lightning protection and test or ???

Thanks

Does it introduce a potential into the building - I suspect not - so not required to have main equipotential bonding

Is it more than likley a self protecting structure in terms of lightning protection - I would say yes - it's location may also put it into the protection zone offered by a rolling sphere analysis or angle of protection method calculation which would probably confirm the self protection and that it's not a risk structure given its relative location to the building

It will need bonding to existing LPS to prevent side flashing and may need a connection to an electrode if you cannot determine connectivity to any rebar etc in the foundation pad

Existing LPS should be made compliant - at least in the area of the stairway

There should be a single point of common bonding from the Building MET to the LPS system

How far your design needs to go with all that is probably a matter of your appointment document but the technical content is generally as above.

Regards

OMS

-------------------------
Failure is always an option

If memory serves then if your existing lightning protection is up to standard it will generally (30 deg coverage from roof edge) cover the external staircase, I would get in a lightning protection specialist to advise on existing system and whether a link to the staircase is required.

Will the external stairs have any lights on them ?

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."

Just an update really. The stairs had no electriclal equipment installed on it. The LPS guys just connect it to existing LPS.