Hospital and large commercial earthing arrangements

[bigspark17]

Just pondering why hospitals and large commercial sites have many many earth pits sited 1 or 2 meters away from outer walls on corners and on pillars.? Is it to do with lightning protection or are the earthing arrangements tns or tt for these installs.?

 

[snowhead]

Lightning

 

[Simonslimline]

IT earthing? (Hospitals)

 

[ermintrude]

Lightning pits - usually on a 6m structural grid . It's connected to structural steel column in the wall construction.

1 or 2m is to avoid the large concrete pad foundation that the column is sitting on.

 

[telectrix]

and they've already dug the pits to hide their mistakes.

 

[Robson689]

Lightning pits - usually on a 6m structural grid . It's connected to structural steel column in the wall construction.

1 or 2m is to avoid the large concrete pad foundation that the column is sitting on.

They should be every 10, 15 or 20 metres depending on the level of protection

 

[ermintrude]

Depends on design. Majority of projects I've worked on its every other col so yeh 6 to 12m

 

[Robson689]

Depends on design. Majority of projects I've worked on its every other col so yeh 6 to 12m

12 I can understand as it's within a few metres of the highest level of protection (level 1) but 6 makes no sense

 

[ermintrude]

When the ground is horrific or its high risk. Usually just did what ever omega suggested TBH.

 

[davesparks]

12 I can understand as it's within a few metres of the highest level of protection (level 1) but 6 makes no sense

Presumably if the ground conditions are poor it could be to get enough rods in to get the resistance low enough

 

[ermintrude]

When your grouting rods in and it's near impossible to get below 2m ...... Middlesbrough riverside is made of clinker and slag from the steel works.

 

[Robson689]

When the ground is horrific or its high risk. Usually just did what ever omega suggested TBH.

Presumably if the ground conditions are poor it could be to get enough rods in to get the resistance low enough

Does make sense in that situation as the more bonds/down conductors you have, the higher your earth readings can be!