grounding service conductor size

[transman2]

I have a new underground service going to a transocket and then a 400 amp fused disconnect outside of building. Then I have 2 - 200amp MLO panels that I'm gonna feed with 2 parralel runs of 3/0 copper to each panel in PVC. What size grounding conductor should I use for this application? Also for the ground rod what size grounding electrode conductor should I use. Could you please refer these questions to code section. Thanks.

 

[jumper]

For GEC see T250.66 and 250.66(A) for rods especially.

For EGC see T250.122

 

[augie47]

Before going there, you might need to address the 200 amp MLO panelboards fed by the 400 amp switch.
This is a violation of 408.36 and perhpas 240.21

 

[jumper]

Before going there, you might need to address the 200 amp MLO panelboards fed by the 400 amp switch.
This is a violation of 408.36 and perhpas 240.21

Read so quick, I did not even pay attention to that. Nice catch.

 

[transman2]

Do my MLO's have to have a main in them to be to code.

 

[augie47]

Not necessarily.. read 408.36

 

[jumper]

That or a separate fused disconnect sized for each panel.

 

[kwired]

Outside of the panelboard overcurrent protection issue - clarification of what conductors you are sizing is needed.

The grounded service conductor is typically the neutral conductor from the source to the service disconnecting means.

It only needs to be sized for the maximum load it will carry but can not be smaller than the size of required grounding electrode conductor from table 250.66.

If you are talking about the load side of the service disconnecting means - you do not have to run a grounded conductor if the load does not require one, but otherwise it only needs to be sized to carry maximum load it will carry but not be smaller than the size of required equipment grounding conductor from table 250.122.

See 250.24(C), 215.2(A)(1)

Grounding electrode conductor to a ground rod does not need to be larger than 6 AWG regardless of what value comes from table 250.66 See 250.66(A)

 

[transman2]

Help

Help

AUGIE47 can you contact me at x

 

[kwired]

AUGIE47 can you contact me at x

Send him a PM.

 

[Strife]

Before going there, you might need to address the 200 amp MLO panelboards fed by the 400 amp switch.
This is a violation of 408.36 and perhpas 240.21

I was gonna say the tap rule applies, but then I noticed the MLO.
However that can be easily rectified by adding a main breaker(considering price and labor to install a 400A switch, 60-70 bucks main breakers won't break the bank).

 

[don_resqcapt19]

The EGC from the 400 amp disconnect to the 200 amp panels is sized based on 400 amps and will require a #3 in each raceway. That assumes you find a way to protect the panels at 200 amps, it also assumes that the feeders between the disconnect and the panel comply with one of the "tap" rules.