quote:

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>I recently moved a small building to a ranch where there is no
>electricity service. The building had been connected to the power
>company and has a Service Entrance Panel on it. I want to connect it to
>a 5500 Watts 120/240 Volt Generator. The Generator has a bonded
>neutral. The neutral and ground are bonded at the Service Entrance
>Panel. Because the Generator has a bonded neutral and the Service
>Entrance Panel ground and neutral are bonded, my question is this.
>
>
>How should I connect the generator at the Service Entrance Panel?
>
>
>Since the Generator will be the only power supply I was trying to avoid
>buying a Transfer Switch. I was going to "unbond" the neutral and
>ground at the Service Entrance Panel and connect the 2 power leads,
>neutral and ground from the Generator to the corresponding connections
>on the Service Entrance Panel. Will this work or am I screwing up?
>
>
>Thanks for your help.

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> On 6 Jul 2005 14:44:14 -0700, "MPO" <mpo@usa.com> wrote:
>
>
>
>
>
> If you are in the US, you need to either unbond the ground and neutral
> at the generator (and connect the generator frame to an equipment
> grounding conductor) and use a 2 pole transfer switch OR use a three
> pole transfer switch. Be sure to follow all local codes. Other
> techniques are often discussed in these groups, but they tend to be
> hazardous and perhaps fatal. Do it right. A transfer switch for this
> size generator is only about $100 - 200 at the local home center and
> typically provides a half a dozen branch circuits. The connection
> from the generator to the transfer switch should not use a "suicide
> cord" with a male plug at both ends. Use a female cord "plug" and
> male receptical (recessed) attached to the building for the
> connection. This receptical is often supplied with the transfer
> switch.
>
> Don't forget to start the generator before connecting loads.
>
> Eric Tappert

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>Eric Tappert wrote:
>
>Can you explain why he needs a transfer switch. You could be
>right, but I want to know. He said there is no electric service
>where the building is relocated. So transfer from what?

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>This was how I was planning on connecting the generator except I was
>only going to place a grounding rod at the generator. Can you explain
>why I would also need a grounding rod at the service entrance panel? Is
>this just an extra precaution or a necessity?
>
>Thank you for your help.

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>On 8 Jul 2005 03:05:42 -0700, "MPO" <mpo@usa.com> wrote:
>
>
>
>NEC section 250.32 requires each building that recieves power from a
>feeder (which is your case, as the "service disconnect" is at the
>separately derived source, i.e. the generator) "shall have a grounding
>electrode". Actually, it needs a grounding electrode system per
>section 250.50. I suspect that there is no underground metallic
>piping or structural reinforcement in the footers of the building that
>are accessible, so this really means a ground rod. Actually two
>ground rods unless you can demonstrate the resistance to ground is
>less than 25 Ohms (unlikely in most of the US). There is an exception
>for a single branch circuit, but that doesn't appear to apply here.
>
>The idea behind this is that every building or structure with a power
>entrance should have a local grounding system. In the case of a
>utility feed, the neutral is bonded to this local system. In the case
>of a feeder supply, the equipment grounding conductor only is bonded
>to this system (the neutral is bonded to the equipment grounding
>conductor at the service disconnect means or the first circuit breaker
>from a separately derived source).
>
>Section 250.30 requires a grounding electrode at the generator. A rod
>is OK if there is not a metallic water pipe or structural steel
>available (which is unlikely for a little genny on a pad...).
>
>The applicable sections referenced above are in the 2005 NEC. The
>rules, however, have not changed over the years even though the
>section numbers have due to editorial issues.
>
>If the generator is physically within a few feet of the building, you
>might get the local jurisdiction having authority to allow just one
>grounding electrode system to ground both the premises and the
>generator.
>
>Hope this helps. I would recommend the NEC handbook (available from
>the NFPA) as a good reference in that it contains a lot of
>explainatory information in addition to the entire code.
>
>Eric Tappert
>