Current On Ground

[puckman]

On A 240 Volt 3 Phase 4 Wire Service . Should The Ground Have Current On It? I Took Amp Readings On The 3 Hot Legs And Was
Supprised When I Got A Reading Of About 12 Amps On The Ground Leg.

 

[Jljohnson]

The "grounded" leg of a 120/240 volt system will carry the imbalanced load of the phase conductors on it. Example - A phase= 14A, b phase+14A, C phase= 24 A....Neutral current will be 10 Amps.

 

[al hildenbrand]

There are also other sources of current, on the service grounded conductor, than the unbalance of the load in the building.

The PoCo primary distribution may have its own unbalance returning, in part, to the supply that it came from (think, the substation transformer supplying the local transformer bank).

The unbalance current of other buildings and their loads will have a portion of their current on your 4-wire 3? 120/240 volt service, especially if a metallic water distribution system is common to the different buildings.

 

[puckman]

The Service Is Labeled 3 Phase 240v 4 Wire Delta . Is This 4th Wire A Ground Or A Neutral ? I See They Have A Trans Going From 240v 3 Wire To 208v 4 Wire. A Little Confused.

 

[al hildenbrand]

On the Power Company side of the service disconnect, the "grounded service conductor" is both a neutral and a ground. . .

The building internal equipment grounding conductors and neutrals are tied together at the service disconnect by the "main bonding jumper", where the grounding electrode system tie in as well.