Need help with grounding problem [RE-wrenches]

[Jason Fisher]

"That's a mistake.  Keep the grounding system completely separate from the
neutral except for one bonding connection at the service panel."

Not necessarily a mistake. NEC 2002- 250.32(B)(2) allows for the bonding of
the grounded conductor at each building or structure's disconnecting means
provided there are no grounding conductors, metallic conduits, water pipes,
etc. run between the structures. This is really no different that how the
utility deals with this subject from your house to your neighbors (for those
of you on grid!). Your service is 120/240 three-wire with no separate
equipment grounding conductor run back to the pole and so is your neighbors.
They are both fed from the same source, they both have equipment grounding
electrodes, and they both have their neutrals bonded at their services. Back
at the pole, a bond connection is also made between the neutral tap and an
equipment grounding conductor that is typically run down the pole to a
ground rod.

In this case, 600 feet is along way to run a new grounding conductor. Let's
see if you can work something else out first. I'd say the sandy soil is
definitely an area worth looking at. I'd recommend that you add more rods
(10' copper clad ideally), at least one at each guy wire and at least two at
the shed (minimum 6' apart) and that you ensure that all of these are bonded
together into one common system (with buried bare wire). Run all the
equipment grounds to this system and make one bond from the neutral to this
system at the shed.

At the house, make sure this same neutral is not bonded in any other
location other that the common point at the main disconnect. Also ensure
that all the ground points are connected together and that there hasn't been
a change to the system such as a switch from metal to plastic water supply
pipe etc. When in doubt, add two more rods and bond everything together.
Might as well add some Deltas or similar protection on everything for the
heck of it.

If you think about it, an induced surge on a grounded conductor that is not
bonded at the shed and run 600' from it's grounding point would have a long
way to travel before it could dissipate at it's grounding point (at the
house). The inverter may prove to be a lower resistance path in this
instance to carry this surge from a neutral to ground.
The reason not to bond the neutral at the shed would be if there was also an
equipment ground run between the two buildings. In this case there would be
a safety concern in that you would have created a parallel path for current
flow on both the neutral and the equipment grounding conductor.

Hope this helps.

Jason Fisher

Aurora Energy LLC
P.O.Box 3315
Annapolis, MD 21403

voice / fax: 410-268-3684
email: jason at aurora-energy.com


-----Original Message-----
From: Hugh Piggott [mailto:hugh at scoraigwind.co.uk]
Sent: Sunday, July 20, 2003 10:58 AM
To: RE-wrenches at topica.com
Subject: Re: Need help with grounding problem [RE-wrenches]

hi

>  Neutral wire is bonded at
>tower location at one point to ground rod system. ...At the
>residence the circuit
>breaker panel is also grounded to the neutral by
>connecting to the 240' well casing.

That's a mistake.  Keep the grounding system completely separate from
teh neutral except for one bonding connection at the service panel.
--
Hugh

http://www.scoraigwind.co.uk/

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael_welch at sbcglobal.net

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
--^----------------------------------------------------------------