I just installed a temp power pole with a temp power box (combination
box with meter, circuit breakers, and 120/240 V receptacles for
providing temporary power to construction site) . I noticed as I was
connecting it, that there was one "bus" bar for the ground wire from
the power company and that there was a separate ground bus bar for the
"true" ground from the ground rod (and the green ground wires from the
receptacles). I also noticed that these two bus bars were not
electrically connected. The ground line (or return line) from the
power company was never really grounded to the box. Is this normal?
I'm tempted to run a bare copper wire between the two "ground" bus
bars, but would like some comments from you electricians out there.
Thanks

wrote in message
...
On 13 Feb 2006 08:35:52 -0800, wrote:

I just installed a temp power pole with a temp power box (combination
box with meter, circuit breakers, and 120/240 V receptacles for
providing temporary power to construction site) . I noticed as I was
connecting it, that there was one "bus" bar for the ground wire from
the power company and that there was a separate ground bus bar for the
"true" ground from the ground rod (and the green ground wires from the
receptacles). I also noticed that these two bus bars were not
electrically connected. The ground line (or return line) from the
power company was never really grounded to the box. Is this normal?
I'm tempted to run a bare copper wire between the two "ground" bus
bars, but would like some comments from you electricians out there.
Thanks


They need to be bonded together.

They are sold unbonded so they you can use it as a main panel or as a
subpanel (in which ground would run back to the main panel before bonding to
neutral)

wrote:
I just installed a temp power pole with a temp power box (combination
box with meter, circuit breakers, and 120/240 V receptacles for
providing temporary power to construction site) . I noticed as I was
connecting it, that there was one "bus" bar for the ground wire from
the power company and that there was a separate ground bus bar for the
"true" ground from the ground rod (and the green ground wires from the
receptacles). I also noticed that these two bus bars were not
electrically connected. The ground line (or return line) from the
power company was never really grounded to the box. Is this normal?
I'm tempted to run a bare copper wire between the two "ground" bus
bars, but would like some comments from you electricians out there.
Thanks

They usually come with a green bond screw to accomplish the bonding;
there is a hole in the neutral bar just for it, but a wire between the
neutral bar and the grounding bar will suffice.

wrote:
I just installed a temp power pole with a temp power box (combination
box with meter, circuit breakers, and 120/240 V receptacles for
providing temporary power to construction site) . I noticed as I was
connecting it, that there was one "bus" bar for the ground wire from
the power company and that there was a separate ground bus bar for the
"true" ground from the ground rod (and the green ground wires from the
receptacles). I also noticed that these two bus bars were not
electrically connected. The ground line (or return line) from the
power company was never really grounded to the box. Is this normal?
I'm tempted to run a bare copper wire between the two "ground" bus
bars, but would like some comments from you electricians out there.
Thanks


Ground and return are not the same thing. And what do you mean by
"true" ground? How did you determine which purpose each bus bar served
and that their purposes were different? Some pre-connections?

--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

Thanks for the responses. Found the "bonding bar" that is supposed to
be installed to ground the neutral from the power company to the box
case. The case is already grounded by the copper wire going to the
ground stake. Thanks again

wrote:
On 14 Feb 2006 05:48:46 -0800, wrote:


Thanks for the responses. Found the "bonding bar" that is supposed to
be installed to ground the neutral from the power company to the box
case. The case is already grounded by the copper wire going to the
ground stake. Thanks again


One thing you need to understand. The "ground" has nothing to do with
clearing a fault (tripping the breaker on a short). All of that
current must go through the bonding jumper and back to the X0
centertap of the transformer. The ground rod is only there to
establish a local reference for the supply, so your tools and the dirt
are at the same potential. Without the bonding jumper your ground rod
is nothing but a worm chaser in a fault.


The "Ground" that comes in from the service and that is also tied to the
water pipes and gas pipes, and the pole in the dirt is a safety
precaution and has to do with lightning protection. It is not normally
part of the circuit as no current flows into the earth, basically unless
its from the sky.

The "ground" you see inside the house which is the 3rd prong is
different. Its actually just a "better" return which is used under
failure conditions. It is also not normally part of the circuit and it
too eventually ties into the earth ground. But its purpose is not
lightning protection.

--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

dnoyeB wrote:
wrote:
On 14 Feb 2006 05:48:46 -0800, wrote:


Thanks for the responses. Found the "bonding bar" that is supposed to
be installed to ground the neutral from the power company to the box
case. The case is already grounded by the copper wire going to the
ground stake. Thanks again


One thing you need to understand. The "ground" has nothing to do with
clearing a fault (tripping the breaker on a short). All of that
current must go through the bonding jumper and back to the X0
centertap of the transformer. The ground rod is only there to
establish a local reference for the supply, so your tools and the dirt
are at the same potential. Without the bonding jumper your ground rod
is nothing but a worm chaser in a fault.


The "Ground" that comes in from the service and that is also tied to the
water pipes and gas pipes, and the pole in the dirt is a safety
precaution and has to do with lightning protection. It is not normally
part of the circuit as no current flows into the earth, basically unless
its from the sky.

The "ground" you see inside the house which is the 3rd prong is
different. Its actually just a "better" return which is used under
failure conditions. It is also not normally part of the circuit and it
too eventually ties into the earth ground. But its purpose is not
lightning protection.

Where is W Tom when ya want ta tim.???