On 12/9/2011 1:37 AM, Bill Horne wrote:
On 12/8/2011 5:36 AM, David Ryeburn wrote:
This evening I checked the blog of VK1OD, which is always interesting.
The most recent posting there is "A medium priced generator set from
eBay". Worth reading.
http://www.vk1od.net/hardware/genset/index.htm
Another example of getting what you pay for.

Thanks for the link. One part caught my eye:

"Since this generator will be used with multiple appliances
of Class II, the neutral was bonded to the earth conductor
to allow the effective use of a portable RCD device."

... and I'm curious why that would be necessary. Of course, the author
is using 240 Volt, 50 Hz power, but I thought everyone kept neutral and
ground leads separate.

73,

Bill, W1AC

By code Neutral and Ground are bonded in the main service entrance box.

I have heard folks tell of portable generators where that is supposed to
"Cause Problems" however any portable generator or fixed generator
designed to supply power to a stick-build house.. Has got to be able to
deal with that.. Since many times a Generator transfer switch (Every one
I've seen) leaves neutral and ground bonded, and in fact cross
connected.. Only the "HOT" (L-1, L-2) Leads are switched.

--
Nothing adds Excitement like something that is none of your business.

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.1873 / Virus Database: 2102/4669 - Release Date: 12/09/11

In article ,

John Davis wrote:



On 12/9/2011 1:37 AM, Bill Horne wrote:

On 12/8/2011 5:36 AM, David Ryeburn wrote:

This evening I checked the blog of VK1OD, which is always interesting.

The most recent posting there is "A medium priced generator set from

eBay". Worth reading.

http://www.vk1od.net/hardware/genset/index.htm

Another example of getting what you pay for.



Thanks for the link. One part caught my eye:



"Since this generator will be used with multiple appliances

of Class II, the neutral was bonded to the earth conductor

to allow the effective use of a portable RCD device."



... and I'm curious why that would be necessary. Of course, the author

is using 240 Volt, 50 Hz power, but I thought everyone kept neutral and

ground leads separate.



73,



Bill, W1AC



By code Neutral and Ground are bonded in the main service entrance box.



I have heard folks tell of portable generators where that is supposed to

"Cause Problems" however any portable generator or fixed generator

designed to supply power to a stick-build house.. Has got to be able to

deal with that.. Since many times a Generator transfer switch (Every one

I've seen) leaves neutral and ground bonded, and in fact cross

connected.. Only the "HOT" (L-1, L-2) Leads are switched.



Actually, the NEC is very jumbled about exactly how this is supposed to

be setup. Mast Electrical Inspectors, and MANY Electrical Engineers,

still do NOT understand this area of the NEC as Published and Amended,

and it still isn't well understood, even with all the changes and

enhancements over then last TWO Decades. There are TWO basic Definitions

that MUST be understood BEFORE one can effectively communicate, about

the Neutral/Ground Bonding, REQUIREMENTS of the NEC.



1. Separately Derived Power Source

2. Portable Power Source



Once those are understood, then one can have a conversation about how

each can be connected to a Grid Tied Electrical Distribution System,

using a NEC REQUIRED and Approved Power Transfer System.



This section of the NEC is a relatively late addition to the Code, and

mostly was ignored before the Y2K Upgrades for Backup Power Systems. Now

with the number of Backup Power systems installations growing

exponentially, it is getting some PLAY, in the Inspection, and

Engineering, ends of the electrical world. there are some really good

explanations published over in the Generator and Motor Forums on

www.smokstak.com, as well as a good bunch of Resident SmartGuys, that

have MAN-Years of Professional Experience, in the Backup Power

Generation field. Just say'en.... This is NOT for the uninitiated, as

even many of those folks that should know and understand this stuff,

clearly do NOT.... YMMV....



--

Bruce in Alaska add path before the @ for email

On Dec 9, 10:37 pm, John Davis wrote:
On 12/9/2011 1:37 AM, Bill Horne wrote:







On 12/8/2011 5:36 AM, David Ryeburn wrote:
This evening I checked the blog of VK1OD, which is always interesting.
The most recent posting there is "A medium priced generator set from
eBay". Worth reading.
http://www.vk1od.net/hardware/genset/index.htm
Another example of getting what you pay for.

Thanks for the link. One part caught my eye:

"Since this generator will be used with multiple appliances
of Class II, the neutral was bonded to the earth conductor
to allow the effective use of a portable RCD device."

... and I'm curious why that would be necessary. Of course, the author
is using 240 Volt, 50 Hz power, but I thought everyone kept neutral and
ground leads separate.

73,

Bill, W1AC

By code Neutral and Ground are bonded in the main service entrance box.

I have heard folks tell of portable generators where that is supposed to
"Cause Problems" however any portable generator or fixed generator
designed to supply power to a stick-build house.. Has got to be able to
deal with that.. Since many times a Generator transfer switch (Every one
I've seen) leaves neutral and ground bonded, and in fact cross
connected.. Only the "HOT" (L-1, L-2) Leads are switched.

--
Nothing adds Excitement like something that is none of your business.

-----
No virus found in this message.
Checked by AVG -www.avg.com
Version: 2012.0.1873 / Virus Database: 2102/4669 - Release Date: 12/09/11

If the generator is dedicated to backup service, is located outdoors
or in another building, and the utility supply system is Multi
Grounded Neutral (MGN) then the neutral should be bonded to the fame
and to all of the available grounding electrodes required by the
electrical code in use in that locality in the same way a utility
transformer has the neutral bonded to the case and to ground. On new
installations done in an area that is governed by the National
Electric Code (NEC) here in the USA the connection to the building
should include all of the ungrounded conductors, the neutral
conductor, and an Equipment Grounding Conductor that is sized to the
generators overcurrent protective device ampacity. Additionally the
transfer switch should have a sufficient number of poles to transfer
the Neutral Conductor from the utility connection to the generator
with the connection to the utility side of the switch made on the load
side of the "Main Bonding Jumper." I don't know if Multi Grounded
Neutral electrical distribution is used outside of North America so
use extreme caution before applying these techniques elsewhere in the
world. When a portable generator is being used with a cord and plug
connection to the transfer mechanism's generator terminals than it is
not considered necessary to isolate the frame of the generator from
the neutral conductor. If you leave the generator plugged into such
an arrangement most of the time you would be well advised to set it up
with a bonding switch so that it can be closed when in portable use
and open when in standby use. If it is bonded in standby use then it
is a bond on the neutral of the buildings wiring on the load side of
the "Service Disconnecting Means" that is expressly forbidden by the
NEC.

--
Tom Horne

On Dec 9, 10:37 pm, John Davis wrote:
On 12/9/2011 1:37 AM, Bill Horne wrote:







On 12/8/2011 5:36 AM, David Ryeburn wrote:
This evening I checked the blog of VK1OD, which is always interesting.
The most recent posting there is "A medium priced generator set from
eBay". Worth reading.
http://www.vk1od.net/hardware/genset/index.htm
Another example of getting what you pay for.

Thanks for the link. One part caught my eye:

"Since this generator will be used with multiple appliances
of Class II, the neutral was bonded to the earth conductor
to allow the effective use of a portable RCD device."

... and I'm curious why that would be necessary. Of course, the author
is using 240 Volt, 50 Hz power, but I thought everyone kept neutral and
ground leads separate.

73,

Bill, W1AC

By code Neutral and Ground are bonded in the main service entrance box.

I have heard folks tell of portable generators where that is supposed to
"Cause Problems" however any portable generator or fixed generator
designed to supply power to a stick-build house.. Has got to be able to
deal with that.. Since many times a Generator transfer switch (Every one
I've seen) leaves neutral and ground bonded, and in fact cross
connected.. Only the "HOT" (L-1, L-2) Leads are switched.

--
Nothing adds Excitement like something that is none of your business.

-----
No virus found in this message.
Checked by AVG -www.avg.com
Version: 2012.0.1873 / Virus Database: 2102/4669 - Release Date: 12/09/11

The situation that would cause the biggest problem is for the
generators neutral to ground bond becoming the return path to the
utility transformer for fault current or the neutral current should an
open neutral occur between the public utilities transformer and the
Service Disconnecting Means. In either case the wiring between the
transfer mechanism and the generator is unlikely to be capable of
safely carrying the current that would be imposed on it. Since that
wiring will usually be only large enough to carry the generators
output, rather than the Neutral current during Utility operation, if
the generator neutral is not transferred or not bonded to the
Equipment Grounding Conductor (EGC) and the Grounding Electrode
Conductors (EGC), if any, at the generator then the wiring from the
generator to the transfer mechanism would die an ignoble death while
trying to carry a current that is much too large for the size of
conductors in the circuit. With a portable generator you simply
unplug the generator from the wiring that connects it to the transfer
mechanism thus breaking the connection through the under ampacity
wiring of the generator circuit. With an optional standby generator
that will normally remain connected to the transfer mechanism it is
important to remove any bonding jumper between the generator neutral
and the frame of the generator or to have a transfer mechanism that
will transfer the neutral at the same time it transfers the ungrounded
current carrying conductors. Either arrangement will break the path
that fault or neutral current would take through the undersized
generator wiring during utility operation.

--
Tom Horne