Is rebar bonding requires?

[Pushpin]

At a Bulk Storage Facility: Is it required to bond rebar in the slabs? There will be a grounging grid with multiple groung rods. What artical says you must bond rebar?:?

 

[bphgravity]

Check out Section 250.50 of the NEC. Qualified concrete-encased electrodes as identified in Section 250.52 are required to be bonded to the grounding electrode system...

 

[rcarroll]

Start at 250.50 for grounding electrode requirements

 

[Dennis Alwon]

Rebar in the slab? or rebar in the footings?

 

[jghrist]

If the slab has a plastic moisture barrier under it, then it is not in contact with the soil and is not a grounding electrode, so you wouldn't have to bond the rebar.

 

[Dennis Alwon]

If the slab has a plastic moisture barrier under it, then it is not in contact with the soil and is not a grounding electrode, so you wouldn't have to bond the rebar.

A slab with rebar does not need bonding regardless. It is not an electrode.

 

[jumper]

Rebar in the slab? or rebar in the footings?

And is it existing in in an already made/poured footing?

 

[Pushpin]

This is a new installation. I was not planning on using rebar as a grounding electrode, but I have been required in the past to bond rebar to the grounding grid by thr electrical inspector. (Jacksonville Florida)
The slab will be in direct contact with the ground. The same is true with canope footers.

 

[Dennis Alwon]

Not sure where the inspector gets that from but it isn't per nec

 

[curt swartz]

I have never seen a slab for a building that didn't include a footing. I'm guessing the inspector is thinking the same.

 

[Dennis Alwon]

I have never seen a slab for a building that didn't include a footing. I'm guessing the inspector is thinking the same.

There are monolithic pours which include the footing and the slab as one pour but around here that is not done much and if it is there is no rebar in the slab just wire mesh. There are also poured footings then the slab done after the block foundation is finished. Either way the slab does not need bonding.

 

[jghrist]

Why is a concrete slab without a moisture barrier not considered a concrete foundation in direct contact with earth? If it has 20' of 1/2" or larger rebar, shouldn't it be considered a concrete-encased electrode? Where are slab foundations excluded from 250.52?

 

[gndrod]

Slab 101

Slab 101

Why is a concrete slab without a moisture barrier not considered a concrete foundation in direct contact with earth? If it has 20' of 1/2" or larger rebar, shouldn't it be considered a concrete-encased electrode? Where are slab foundations excluded from 250.52?

Slab floors use a grid mesh. The stemwall perimeter or monolithic turned slab 'footers' on natural grade both require rebar in IRC and old UBC codes but may not be a local adopted code.

In new or remodel construction, a continuous #4 rebar will exist for compliant footers. IRCR403.1.3. The UFER ground electrode in footer is "present" for GEC bonding compliance.[250.52(A)(3)]