Do meter box and main breaker box have their own grounds?

[bgdl4]

In a new home construction, I understand the meter box requires a ground wire to a ground rod, but if in a poured concrete basement(footings, walls and slab) where the main breaker box(200 A) is about 60 feet away from the meter in a mechanical room, should the concrete contractor build in a below slab and in wall embedded rebar rod from which a ground strap(?) would penetrate the inside wall to allow a ground connection to the main breaker box?

 

[don_resqcapt19]

If there is 20' or more of 1/2" or larger rebar in a foundation or footing that has direct contact with the earth, that is a concrete encased electrode and is required to be used as part of the building's grounding electrode system.

How are the service conductors getting from the meter to the panel that is 60' away?

 

[bgdl4]

Do meter box and main breaker box have their own grounds?

Hi Don, thanks for getting back to me, so to keep on top of this, if the concrete contractor specifies #6 wire reinforce in walls at 4 foot intervals and 1/2" rebar vertically between footing and walls, would the 20' of rebar condition be wise to include in the quote? I have not seen the quote yet but would appreciate advice selecting between RMC, GMC and IMC encasing the feeder conductors from meter box to main breaker box. The feeder conduit will travel between and through open floor trusses.

 

[don_resqcapt19]

Hi Don, thanks for getting back to me, so to keep on top of this, if the concrete contractor specifies #6 wire reinforce in walls at 4 foot intervals and 1/2" rebar vertically between footing and walls, would the 20' of rebar condition be wise to include in the quote?

Here is what the code says as far as the use of a concrete encased electrode. If what is being installed meets the rules in (1) shown below, you are required to use the rebar as an electrode.

230.52(A)(3) Concrete-Encased Electrode. A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either (1) or (2):

(1) One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (½ in.) in diameter, installed in one continuous 6.0 m (20 ft) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or

(2) Bare copper conductor not smaller than 4 AWG Metallic components shall be encased by at least 50 mm (2 in.) of concrete and shall be located horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth or within vertical foundations or structural components or members that are in direct contact with the earth.

If multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the
grounding electrode system.

Informational Note: Concrete installed with insulation, vapor barriers, films or similar items separating the concrete from the
earth is not considered to be in “direct contact” with the earth.

I have not seen the quote yet but would appreciate advice selecting between RMC, GMC and IMC encasing the feeder conductors from meter box to main breaker box. The feeder conduit will travel between and through open floor trusses.

You will have a problem with that in most jurisdictions. It is a violation of 230.70(A)(1).

230.70(A)(1) Readily Accessible Location. The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.

it is very likely that the AHJ will require an outside service disconnect and not permit that much service conductor inside the building. That would also mean that the all of the grounding electrode conductors would have to be connected at the meter or the outside service disconnect and you will need to install the two ungrounded conductors, the grounded (neutral) conductor and an EGC between the outside service disconnect and the interior panel. The code would permit a metallic conduit to be used as the required EGC.

 

[GoldDigger]

Whatever else you do, AFAIK you are not allowed to use a length of rebar in concrete to provide the EGC connection from one place in the building to another.

 

[bgdl4]

Do meter box and main breaker box have their own grounds?

Hi Don, once again thank you for your help, I should have been more explicit in describing the connection between the meter box and the main breaker box, of course their should be a disconnect just after the meter box since the distance between meter and main breaker box is over 3'. Thanks GoldDigger for your input also.