Bonding the rebar in any equipment foundation/slab

[TimRo]

Bonding the rebar in any equipment foundation/slab (GSU transformers, HRSG, CTG, etc)to the grounding grid is very clear identified and addressed in IEEE 665 and 142. NEC 2008 is clear in connecting the rebar to the grounding grid. art 250. NESC-2007 is addressing this question in section 9. rule 094. The benefit is not only in having a low grounding resistance, but also a good lightning protection. Can somebody explain why electrical designers do not adhere to this idea, and oppose this. What could go wrong in doing this?

 

[cuky2000]

There are people with concerns to degrade the foundation. Some of the issues had been discussed for years are:

1- Damage to tower footing from the flow of high current fault or lightning creating sudden moisture evaporation that may crack the concrete.

2- Galvanic corrosion with DC current rectified at the concrete rebar interface.

Should be fare to say that some engineers and even utilities are addopting the practice tie the foundation rebar to the grid.

 

[WoodrowJWeen]

I always advocate bonding to the rebar. Certainly a lot more effective than the "magic triangle".