Re: Stus-List Inverter to Outlet Via Extension Cord?

[Della Barba, Joe via CnC-List]

I just checked my inverters and they both are "center grounded". They show 60 
volts from hot to ground and 60 volts from neutral to ground. This actually has 
an advantage where if a human gets their hands on a wire and is grounded, they 
only get a 60 volt shock*. My ground faults work with this setup too. The 
disadvantage is any equipment that has any interconnection between neutral and 
ground would cause a dead short. Such a thing should not exist, but sometimes 
it does and no one notices. It isn't good anyway, but you REALLY don't want 
mixed neutrals and grounds on a boat. You end up feeding AC into the water to 
some extent even with good wiring and a lot of AC with bad wiring.
* I suspect that this is not on purpose, but rather an artifact of a push-pull 
design in the inverter that was just easier to do with the center point 
grounded. More expensive inverters designed for hard wiring do not do this.

Joe
Coquina
C 35 MK I

From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of David via 
CnC-List
Sent: Monday, November 28, 2016 17:48
To: cnc-list@cnc-list.com
Cc: David <davidrisc...@msn.com>
Subject: Re: Stus-List Inverter to Outlet Via Extension Cord?


So I know enough to know to be careful and decided to isolate the inverter to 
its own dedicated newly installed plug. Properly wired and chassis grounded as 
well.



Its all we will need.  Thanks for everyone's input.


David F. Risch
(401) 419-4650 (cell)


From: CnC-List 
<cnc-list-boun...@cnc-list.com<mailto:cnc-list-boun...@cnc-list.com>> on behalf 
of Tim Goodyear via CnC-List 
<cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>>
Sent: Monday, October 24, 2016 7:12 PM
To: cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>
Cc: Tim Goodyear; Michael Brown
Subject: Re: Stus-List Inverter to Outlet Via Extension Cord?

Like 'ground' systems, marine systems are required to connect neutral to ground 
at the source of power, whether that is somewhere at the top of the dock for 
shore power, or at the generator or inverter.  One of the most important 
connections at the inverter is from chassis ground to the boat's grounding bus. 
On a marine inverter, there should be a switch that opens the ground to neutral 
connection when it is providing pass-through shore power and closes it when it 
is generating AC power itself.  I presume that the WM 1kW versions have a 
neutral/ground connection within them, but it would be very worth checking!

Tim
Ex-Mojito
Newport, RI

On Oct 24, 2016, at 2:31 PM, Michael Brown via CnC-List 
<cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> wrote:
Hopefully the inverter will come with very clear instructions on how to
handle ground and neutral.

For normal power, ie shore power, this is the US code:

"The National Electrical Code ( NEC ) requires the AC source to have a Neutral 
to ground bond
and that there be only one such bond in the entire AC system."

So only at the distribution panel is there a bond between neutral and ground. 
They should
never be connected together intentionally at the load. This document covers 
grounding and
bonding, may also cure insomnia.

https://www.engineereducators.com/docs/groundingandbonding2-2.pdf

Grounding an AC system is done to limit the effect of a lightning strike, maybe 
an upstream
over voltage fault. Bonding the green wire that comes in a three prong plug ( 
also called a
ground ) to Neutral at the distribution panel is to ensure a low resistance 
return path for
a fault. So if anything happens the desired effect is that a hot to ground 
short will occur
which in turn will cause an over current surge blowing the circuit breakers.

A person can be electrocuted even with a properly installed and grounded AC 
system
without the circuit breakers tripping.

Unless an inverter has some specific design that uses a ground bonding the 
Neutral and
ground together is not going to do much. Check out the last Q from Xantrex 
here:

http://www.xantrex.com/documents/tech-doctor/universal/tech4-universal.pdf

Similarly with an inverter connected to a battery that is not grounded a GFCI 
should
never trip. Theoretically in a floating system the power has to come out of the 
Hot
lead and return in the Neutral. There will never be a ground fault to trip a 
GFCI.
There is no ground.

I suppose an inverter manufacturer could create a third connection back to the
power circuit Neutral that bypasses the GFCI. A short to that wire would cause
an imbalance and trip the GFCI. Then you would be connecting a floating
Neutral to the loads "ground" which may be exactly what the Xantrex article says
not to do.

Michael Brown
Windburn
C 30-1



From: Ron Ricci <rvri...@gmail.com<mailto:rvri...@gmail.com>>

David,

I've followed some of this thread and have a few concerns where some have
mentioned using an inexpensive inverter.

Using an inverter that is not int

Re: Stus-List Inverter to Outlet Via Extension Cord?

[David via CnC-List]

So I know enough to know to be careful and decided to isolate the inverter to 
its own dedicated newly installed plug. Properly wired and chassis grounded as 
well.


Its all we will need.  Thanks for everyone's input.


David F. Risch
(401) 419-4650 (cell)



From: CnC-List <cnc-list-boun...@cnc-list.com> on behalf of Tim Goodyear via 
CnC-List <cnc-list@cnc-list.com>
Sent: Monday, October 24, 2016 7:12 PM
To: cnc-list@cnc-list.com
Cc: Tim Goodyear; Michael Brown
Subject: Re: Stus-List Inverter to Outlet Via Extension Cord?

Like 'ground' systems, marine systems are required to connect neutral to ground 
at the source of power, whether that is somewhere at the top of the dock for 
shore power, or at the generator or inverter.  One of the most important 
connections at the inverter is from chassis ground to the boat's grounding bus. 
On a marine inverter, there should be a switch that opens the ground to neutral 
connection when it is providing pass-through shore power and closes it when it 
is generating AC power itself.  I presume that the WM 1kW versions have a 
neutral/ground connection within them, but it would be very worth checking!

Tim
Ex-Mojito
Newport, RI

On Oct 24, 2016, at 2:31 PM, Michael Brown via CnC-List 
<cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> wrote:

Hopefully the inverter will come with very clear instructions on how to
handle ground and neutral.

For normal power, ie shore power, this is the US code:

"The National Electrical Code ( NEC ) requires the AC source to have a Neutral 
to ground bond
and that there be only one such bond in the entire AC system."

So only at the distribution panel is there a bond between neutral and ground. 
They should
never be connected together intentionally at the load. This document covers 
grounding and
bonding, may also cure insomnia.

https://www.engineereducators.com/docs/groundingandbonding2-2.pdf

Grounding an AC system is done to limit the effect of a lightning strike, maybe 
an upstream
over voltage fault. Bonding the green wire that comes in a three prong plug ( 
also called a
ground ) to Neutral at the distribution panel is to ensure a low resistance 
return path for
a fault. So if anything happens the desired effect is that a hot to ground 
short will occur
which in turn will cause an over current surge blowing the circuit breakers.

A person can be electrocuted even with a properly installed and grounded AC 
system
without the circuit breakers tripping.

Unless an inverter has some specific design that uses a ground bonding the 
Neutral and
ground together is not going to do much. Check out the last Q from Xantrex 
here:

http://www.xantrex.com/documents/tech-doctor/universal/tech4-universal.pdf

Similarly with an inverter connected to a battery that is not grounded a GFCI 
should
never trip. Theoretically in a floating system the power has to come out of the 
Hot
lead and return in the Neutral. There will never be a ground fault to trip a 
GFCI.
There is no ground.

I suppose an inverter manufacturer could create a third connection back to the
power circuit Neutral that bypasses the GFCI. A short to that wire would cause
an imbalance and trip the GFCI. Then you would be connecting a floating
Neutral to the loads "ground" which may be exactly what the Xantrex article says
not to do.

Michael Brown
Windburn
C 30-1




From: Ron Ricci <rvri...@gmail.com<mailto:rvri...@gmail.com>>

David,

I've followed some of this thread and have a few concerns where some have
mentioned using an inexpensive inverter.

Using an inverter that is not intended for marine use or not properly
grounded can cause problems.  An inverter can produce short duration spikes
which exceed the insulation rating of most wires.  This becomes an issue in
wet areas and will cause insulation failure.

There are other issues relating to inducing corrosion.  A friend who
coincidentally keeps his boat in RI and is the technical support guru for a
company that sells variable frequency drives (inverters for AC motors) had
to replace his propellers when he used an inverter he bought from Harbor
Freight.  It was probably fine for anything other than marine use.

If the neutral on the inverter is not grounded, the neutral can kill you
regardless of the presence of a GFCI.

Just my thoughts,

Ron Ricci
S/V Patriot
C 37+
Bristol, RI
___

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  
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All Contributions are greatly appreciated!
___

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  
https://www.paypal.me/stumurray

All Contributions are greatly appreciated!

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Michael Brown via CnC-List]

 
 
 Interesting topic considering it does reduce down to connecting three wires
more or less. The executive overview is that hopefully the inverter, circuit 
breaker
panel and GFCI will come with good instructions on how they need to be wired.

At least some of the GFCI are recommended for use in two wire only retrofits.
The requirement is that somewhere at the power source there is a ground.
These units may come with a sticker saying "non grounded outlet". The test
button still works since it jumpers over the sensing circuitry from hot to
neutral, no EGC required.

Maybe this will explain it a lot better:

https://www.nema.org/Products/Documents/NEMA-GFCI-2012-Field-Representative-Presentation.pdf

Check out page 14.

A point I was commenting on was that even with a correctly wired AC system, EGC 
and earth ground
bonded together at the correct location and everything to spec a person can 
still get electrocuted.
It is a safety requirement though more so to help the utility with lightning 
strikes and to ensure the
OCPD ( circuit breaker ) trips if a load shorts out. Tongue in cheek was the 
comment that the ground
path is likely the current return if a person gets a shock. If there is a 
problem with the earth ground
even a GFCI may not help. In a marina or club if all the grounds are correctly 
tied together a persons
safety is dependent on the quality of the worst installation using shore power.

Michael Brown
Windburn
C 30-1


From: Josh Muckley  

"So if the inverter is floating and has no ground you cannot get a ground 
fault shock. If there is a ground wired in you could get a shock but the 
GFCI should trip. Maybe having the GFCI in is a good thing in that if there 
was a defect in the load you would never know it without a ground. With 
it the GFCI would keep tripping letting you know something is wrong." 
 
Michael, As you stated the GFCI is comparing the current on both the hot 
and neutral.  When a difference is sensed it trips the GFCI.  You mentioned 
that without a ground the GFCI won't trip.  2 thoughts come to mind. 
First, without a ground, the GFCI won't trip during a "test".  The 
pushbutton connects a high resistance to the ground prong creating a leak 
path for current so in that case you're completely right the GFCI won't 
trip.  Second, the GFCI is still sensitive to a difference in current 
between hot and neutral.  You can wire a GFCI ungrounded and it will still 
trip during a fault.  You need a leak path.  Most GFCI outlets are 
sensitive to 5mA.  The idea that the inverter is using an ungrounded system 
and as a result, you won't trip the GFCI sounds synonymous with the idea 
that since I'm wearing rubber shoes, standing on carpet, in a wood frame 
house I won't get shocked by the hot.  I can tell you from experience, you 
will get shocked! 
 
All of this discussion about floating AC actually gets me thinking about 
whether or not the GFCI outlet has a disconnect on both the hot and neutral 
lines.  Even if the GFCI trips the neutral prong may still be connected to 
the neutral wire which in a home isn't a problem, but with a floating AC 
system you could still be exposed to voltage.  We had problems similar to 
this while on Navy ships.  The crew had bought generic computer surge 
protectors which all needed replaced with high dollar ones since the 
generic ones only protect the hot terminal. 
 
Josh Muckley 
S/V Sea Hawk 
1989 C 37+ 
Solomons, MD 
 

 

 

___

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  
https://www.paypal.me/stumurray

All Contributions are greatly appreciated!

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Josh Muckley via CnC-List]

"So if the inverter is floating and has no ground you cannot get a ground
fault shock. If there is a ground wired in you could get a shock but the
GFCI should trip. Maybe having the GFCI in is a good thing in that if there
was a defect in the load you would never know it without a ground. With
it the GFCI would keep tripping letting you know something is wrong."

Michael, As you stated the GFCI is comparing the current on both the hot
and neutral.  When a difference is sensed it trips the GFCI.  You mentioned
that without a ground the GFCI won't trip.  2 thoughts come to mind.
First, without a ground, the GFCI won't trip during a "test".  The
pushbutton connects a high resistance to the ground prong creating a leak
path for current so in that case you're completely right the GFCI won't
trip.  Second, the GFCI is still sensitive to a difference in current
between hot and neutral.  You can wire a GFCI ungrounded and it will still
trip during a fault.  You need a leak path.  Most GFCI outlets are
sensitive to 5mA.  The idea that the inverter is using an ungrounded system
and as a result, you won't trip the GFCI sounds synonymous with the idea
that since I'm wearing rubber shoes, standing on carpet, in a wood frame
house I won't get shocked by the hot.  I can tell you from experience, you
will get shocked!

All of this discussion about floating AC actually gets me thinking about
whether or not the GFCI outlet has a disconnect on both the hot and neutral
lines.  Even if the GFCI trips the neutral prong may still be connected to
the neutral wire which in a home isn't a problem, but with a floating AC
system you could still be exposed to voltage.  We had problems similar to
this while on Navy ships.  The crew had bought generic computer surge
protectors which all needed replaced with high dollar ones since the
generic ones only protect the hot terminal.

Josh Muckley
S/V Sea Hawk
1989 C 37+
Solomons, MD

On Oct 24, 2016 7:07 PM, "Michael Brown via CnC-List" 
wrote:

> I think you have it, that is how a GFCI works.
>
> In the case of an inverter that is floating use of a ground is a bit of an
> oxymoron.
>
> The principle is that every electron that comes out of one connection has
> to go
> back to the other connection. If the GFCI is directly connected to the two
> connections
> on the inverter, then two connections to the load the current should
> always be
> the same. There is no other path for the electrons to take.
>
> As Joe points out you should be able to grab either line and stand in a
> puddle
> of water without getting a shock or tripping the GFCI. There is no path
> for the
> current back to the other terminal.
>
> If you add a ground or connect to a ground now there is a second path
> likely to whichever side is deemed the neutral. That connection is to the
> power source and bypasses the GFCI. So if the ground conducts any
> current the flow through the GFCI is not balanced and it will trip.
>
> The ground lead does not have to connect to the GFCI, maybe it does
> but there is no need.
>
> The two UL standards, which may seem a bit strange at first, make sense
> in that they accommodate what may be already in place that the inverter
> is connecting to. In a power failure backup mode to a wired building there
> will be a ground to neutral bond already at the distribution panel if the
> inverter is connecting there. With no utility involved ( off grid ) the
> wiring
> codes may still require a ground and bonding in the inverter.
>
> On a boat I do not know what to recommend. If the loads ( appliances )
> are all three prong, all the outlets are wired with ground and the inverter
> supports a bonded ground and GFCI maybe that is the way to hook it up.
> If the inverter auto switches from battery to shore power then you are
> wired normally when on shore power. If the AC is stand alone or a three
> pole switch completely disconnects when going to shore power wiring
> in a ground and GFCI is not going to hurt. Doesn't help much either.
>
> So if the inverter is floating and has no ground you cannot get a ground
> fault shock. If there is a ground wired in you could get a shock but the
> GFCI should trip. Maybe having the GFCI in is a good thing in that if there
> was a defect in the load you would never know it without a ground. With
> it the GFCI would keep tripping letting you know something is wrong.
>
> Not that there is ever any wiring problems on old sailboats 
>
> Michael Brown
> Windburn
> C 30-1
>
>
> From: Tortuga 
>
> "Similarly with an inverter connected to a battery that is not grounded a
> GFCI should
> never trip. Theoretically in a floating system the power has to come out
> of
> the Hot
> lead and return in the Neutral. There will never be a ground fault to trip
> a GFCI.
> There is no ground."
>
> I'm not an electrician, but my limited understanding is that a Ground
> Fault
> Circuit Interrupter monitors the hot and neutral leads and 

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Tim Goodyear via CnC-List]

Like 'ground' systems, marine systems are required to connect neutral to ground 
at the source of power, whether that is somewhere at the top of the dock for 
shore power, or at the generator or inverter.  One of the most important 
connections at the inverter is from chassis ground to the boat's grounding bus. 
On a marine inverter, there should be a switch that opens the ground to neutral 
connection when it is providing pass-through shore power and closes it when it 
is generating AC power itself.  I presume that the WM 1kW versions have a 
neutral/ground connection within them, but it would be very worth checking!

Tim
Ex-Mojito
Newport, RI

> On Oct 24, 2016, at 2:31 PM, Michael Brown via CnC-List 
>  wrote:
> 
> Hopefully the inverter will come with very clear instructions on how to
> handle ground and neutral.
> 
> For normal power, ie shore power, this is the US code:
> 
> "The National Electrical Code ( NEC ) requires the AC source to have a 
> Neutral to ground bond
> and that there be only one such bond in the entire AC system."
> 
> So only at the distribution panel is there a bond between neutral and ground. 
> They should
> never be connected together intentionally at the load. This document covers 
> grounding and
> bonding, may also cure insomnia.
> 
> https://www.engineereducators.com/docs/groundingandbonding2-2.pdf
> 
> Grounding an AC system is done to limit the effect of a lightning strike, 
> maybe an upstream
> over voltage fault. Bonding the green wire that comes in a three prong plug ( 
> also called a
> ground ) to Neutral at the distribution panel is to ensure a low resistance 
> return path for
> a fault. So if anything happens the desired effect is that a hot to ground 
> short will occur
> which in turn will cause an over current surge blowing the circuit breakers.
> 
> A person can be electrocuted even with a properly installed and grounded AC 
> system
> without the circuit breakers tripping.
> 
> Unless an inverter has some specific design that uses a ground bonding the 
> Neutral and
> ground together is not going to do much. Check out the last Q from Xantrex 
> here:
> 
> http://www.xantrex.com/documents/tech-doctor/universal/tech4-universal.pdf
> 
> Similarly with an inverter connected to a battery that is not grounded a GFCI 
> should
> never trip. Theoretically in a floating system the power has to come out of 
> the Hot
> lead and return in the Neutral. There will never be a ground fault to trip a 
> GFCI.
> There is no ground.
> 
> I suppose an inverter manufacturer could create a third connection back to the
> power circuit Neutral that bypasses the GFCI. A short to that wire would cause
> an imbalance and trip the GFCI. Then you would be connecting a floating
> Neutral to the loads "ground" which may be exactly what the Xantrex article 
> says
> not to do.
> 
> Michael Brown
> Windburn
> C 30-1
>  
> 
> 
> 
> From: Ron Ricci  
> 
> David, 
> 
> I've followed some of this thread and have a few concerns where some have 
> mentioned using an inexpensive inverter.   
> 
> Using an inverter that is not intended for marine use or not properly 
> grounded can cause problems.  An inverter can produce short duration spikes 
> which exceed the insulation rating of most wires.  This becomes an issue in 
> wet areas and will cause insulation failure.   
> 
> There are other issues relating to inducing corrosion.  A friend who 
> coincidentally keeps his boat in RI and is the technical support guru for a 
> company that sells variable frequency drives (inverters for AC motors) had 
> to replace his propellers when he used an inverter he bought from Harbor 
> Freight.  It was probably fine for anything other than marine use. 
> 
> If the neutral on the inverter is not grounded, the neutral can kill you 
> regardless of the presence of a GFCI.   
> 
> Just my thoughts, 
> 
> Ron Ricci 
> S/V Patriot 
> C 37+ 
> Bristol, RI 
> ___
> 
> This list is supported by the generous donations of our members. If you wish 
> to make a contribution to offset our costs, please go to:  
> https://www.paypal.me/stumurray
> 
> All Contributions are greatly appreciated!
___

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  
https://www.paypal.me/stumurray

All Contributions are greatly appreciated!

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Michael Brown via CnC-List]

I think you have it, that is how a GFCI works.

In the case of an inverter that is floating use of a ground is a bit of an 
oxymoron.

The principle is that every electron that comes out of one connection has to go
back to the other connection. If the GFCI is directly connected to the two 
connections
on the inverter, then two connections to the load the current should always be
the same. There is no other path for the electrons to take.

As Joe points out you should be able to grab either line and stand in a puddle
of water without getting a shock or tripping the GFCI. There is no path for the
current back to the other terminal.

If you add a ground or connect to a ground now there is a second path
likely to whichever side is deemed the neutral. That connection is to the
power source and bypasses the GFCI. So if the ground conducts any
current the flow through the GFCI is not balanced and it will trip.

The ground lead does not have to connect to the GFCI, maybe it does
but there is no need.

The two UL standards, which may seem a bit strange at first, make sense
in that they accommodate what may be already in place that the inverter
is connecting to. In a power failure backup mode to a wired building there
will be a ground to neutral bond already at the distribution panel if the
inverter is connecting there. With no utility involved ( off grid ) the wiring
codes may still require a ground and bonding in the inverter.

On a boat I do not know what to recommend. If the loads ( appliances )
are all three prong, all the outlets are wired with ground and the inverter
supports a bonded ground and GFCI maybe that is the way to hook it up.
If the inverter auto switches from battery to shore power then you are
wired normally when on shore power. If the AC is stand alone or a three
pole switch completely disconnects when going to shore power wiring
in a ground and GFCI is not going to hurt. Doesn't help much either.

So if the inverter is floating and has no ground you cannot get a ground
fault shock. If there is a ground wired in you could get a shock but the
GFCI should trip. Maybe having the GFCI in is a good thing in that if there
was a defect in the load you would never know it without a ground. With
it the GFCI would keep tripping letting you know something is wrong.

Not that there is ever any wiring problems on old sailboats 

Michael Brown
Windburn
C 30-1



From: Tortuga  

"Similarly with an inverter connected to a battery that is not grounded a 
GFCI should 
never trip. Theoretically in a floating system the power has to come out of 
the Hot 
lead and return in the Neutral. There will never be a ground fault to trip 
a GFCI. 
There is no ground." 
 
I'm not an electrician, but my limited understanding is that a Ground Fault 
Circuit Interrupter monitors the hot and neutral leads and interrupts the 
circuit almost instantly if it detects a difference between them. The 
ground lead does not come into it. 
 
The Xantrex Freedom HF 1000 that I mentioned in an earlier post is *UL458* 
-listed. 
 
"The two UL standards differ in how they handle AC system grounding: 
*UL1741*-listed inverters must allow for the neutral-to-ground bond to 
*only* occur at the main AC service panel. *UL458*-listed inverters have 
internal neutral-to-ground switching relays to allow for this bond to occur 
at the inverter if in off-grid mode, OR at the utility power service if it 
is connected to a utility hookup." 
 
Perhaps I'm missing something. 
 
Derek Kennedy 
SV Tortuga, 30 mk1 
Ballantyne's Cove, NS 
___

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  
https://www.paypal.me/stumurray

All Contributions are greatly appreciated!

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Della Barba, Joe via CnC-List]

GFCI outlets compare current in the hot and neutral and trip if it is not the 
same.
If an inverter has no connection at all to ground, i.e. a floating AC system, 
connecting either hot or neutral to ground would have no effect and not trip 
the ground fault. You could, in theory, sit neck deep in water and hold onto 
one of the AC wires and not feel a thing. (DO NOT TRY AT HOME)
The reason shore power works with GCFI outlets is the neutral and ground are 
connected. If you come into contact with a hot wire and your body is grounded 
at all, the current will flow out the hot, through you, and back to ground via 
some other means than the neutral wire. The ground fault senses this and trips. 
Likewise leaks and shorts to a grounded piece of equipment would trip it. Do 
note you can still kill yourself by grabbing hot and neutral.
I have a 300 watt and 1000 watt inverter and can switch between them. Either 
one will trip the ground faults if tested, so they both connect the AC side to 
ground somehow back through the DC negative connection. I need to go test them 
and see exactly how. It could be the standard neutral to ground connection or 
it could be something goofy like the power transistors being grounded at a 
center point and each side of the AC circuit is on one side of a center ground.
Just an FYI, am 99% sure commercial ships got away from grounding issues and 
use floating AC.

Joe
Coquina
C 35 MK I


From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Tortuga via 
CnC-List
Sent: Monday, October 24, 2016 15:49
To: cnc-list@cnc-list.com
Cc: Tortuga <tortugas...@gmail.com>
Subject: Re: Stus-List Inverter to Outlet Via Extension Cord?

"Similarly with an inverter connected to a battery that is not grounded a GFCI 
should
never trip. Theoretically in a floating system the power has to come out of the 
Hot
lead and return in the Neutral. There will never be a ground fault to trip a 
GFCI.
There is no ground."

I'm not an electrician, but my limited understanding is that a Ground Fault 
Circuit Interrupter monitors the hot and neutral leads and interrupts the 
circuit almost instantly if it detects a difference between them. The ground 
lead does not come into it.

The Xantrex Freedom HF 1000 that I mentioned in an earlier post is UL458-listed.

"The two UL standards differ in how they handle AC system grounding: 
UL1741-listed inverters must allow for the neutral-to-ground bond to only occur 
at the main AC service panel. UL458-listed inverters have internal 
neutral-to-ground switching relays to allow for this bond to occur at the 
inverter if in off-grid mode, OR at the utility power service if it is 
connected to a utility hookup."

Perhaps I'm missing something.

Derek Kennedy
SV Tortuga, 30 mk1
Ballantyne's Cove, NS


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Re: Stus-List Inverter to Outlet Via Extension Cord?

[Tortuga via CnC-List]

"Similarly with an inverter connected to a battery that is not grounded a
GFCI should
never trip. Theoretically in a floating system the power has to come out of
the Hot
lead and return in the Neutral. There will never be a ground fault to trip
a GFCI.
There is no ground."

I'm not an electrician, but my limited understanding is that a Ground Fault
Circuit Interrupter monitors the hot and neutral leads and interrupts the
circuit almost instantly if it detects a difference between them. The
ground lead does not come into it.

The Xantrex Freedom HF 1000 that I mentioned in an earlier post is *UL458*
-listed.

"The two UL standards differ in how they handle AC system grounding:
*UL1741*-listed inverters must allow for the neutral-to-ground bond to
*only* occur at the main AC service panel. *UL458*-listed inverters have
internal neutral-to-ground switching relays to allow for this bond to occur
at the inverter if in off-grid mode, OR at the utility power service if it
is connected to a utility hookup."

Perhaps I'm missing something.

Derek Kennedy
SV Tortuga, 30 mk1
Ballantyne's Cove, NS
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Re: Stus-List Inverter to Outlet Via Extension Cord?

[Michael Brown via CnC-List]

Hopefully the inverter will come with very clear instructions on how to
handle ground and neutral.

For normal power, ie shore power, this is the US code:

"The National Electrical Code ( NEC ) requires the AC source to have a Neutral 
to ground bond
and that there be only one such bond in the entire AC system."

So only at the distribution panel is there a bond between neutral and ground. 
They should
never be connected together intentionally at the load. This document covers 
grounding and
bonding, may also cure insomnia.

https://www.engineereducators.com/docs/groundingandbonding2-2.pdf

Grounding an AC system is done to limit the effect of a lightning strike, maybe 
an upstream
over voltage fault. Bonding the green wire that comes in a three prong plug ( 
also called a
ground ) to Neutral at the distribution panel is to ensure a low resistance 
return path for
a fault. So if anything happens the desired effect is that a hot to ground 
short will occur
which in turn will cause an over current surge blowing the circuit breakers.

A person can be electrocuted even with a properly installed and grounded AC 
system
without the circuit breakers tripping.

Unless an inverter has some specific design that uses a ground bonding the 
Neutral and
ground together is not going to do much. Check out the last Q from Xantrex 
here:

http://www.xantrex.com/documents/tech-doctor/universal/tech4-universal.pdf

Similarly with an inverter connected to a battery that is not grounded a GFCI 
should
never trip. Theoretically in a floating system the power has to come out of the 
Hot
lead and return in the Neutral. There will never be a ground fault to trip a 
GFCI.
There is no ground.

I suppose an inverter manufacturer could create a third connection back to the
power circuit Neutral that bypasses the GFCI. A short to that wire would cause
an imbalance and trip the GFCI. Then you would be connecting a floating
Neutral to the loads "ground" which may be exactly what the Xantrex article says
not to do.

Michael Brown
Windburn
C 30-1
 




From: Ron Ricci  

David, 
 
I've followed some of this thread and have a few concerns where some have 
mentioned using an inexpensive inverter.   
 
Using an inverter that is not intended for marine use or not properly 
grounded can cause problems.  An inverter can produce short duration spikes 
which exceed the insulation rating of most wires.  This becomes an issue in 
wet areas and will cause insulation failure.   
 
There are other issues relating to inducing corrosion.  A friend who 
coincidentally keeps his boat in RI and is the technical support guru for a 
company that sells variable frequency drives (inverters for AC motors) had 
to replace his propellers when he used an inverter he bought from Harbor 
Freight.  It was probably fine for anything other than marine use.  
 
If the neutral on the inverter is not grounded, the neutral can kill you 
regardless of the presence of a GFCI.   
 
Just my thoughts, 
 
Ron Ricci 
S/V Patriot 
C 37+ 
Bristol, RI 
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Re: Stus-List Inverter to Outlet Via Extension Cord?

[Della Barba, Joe via CnC-List]

I have a West Marine 1000 Watt inverter that I wired to a few outlets with no 
apparent ill effects. I use a shore power sensing relay I got from West to 
switch them between inverter and shore power. I used a GFCI outlet and it works 
when I test it. I have not tested a neutral>ground leak, maybe I should? The 
relay switches both hot and neutral wires and the green wire stays common.
So far the biggest shock danger I have found with inverters is people assuming 
the shore power cord being disconnected = no AC power anywhere.
(http://www.westmarine.com/buy/kisae-technology--ac-transfer-switches--P014159982?recordNum=18)

Joe
Coquina


-Original Message-
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Ron Ricci 
via CnC-List
Sent: Monday, October 24, 2016 09:20
To: cnc-list@cnc-list.com
Cc: Ron Ricci <rvri...@gmail.com>
Subject: Re: Stus-List Inverter to Outlet Via Extension Cord?

David,

I've followed some of this thread and have a few concerns where some have
mentioned using an inexpensive inverter.  

Using an inverter that is not intended for marine use or not properly
grounded can cause problems.  An inverter can produce short duration spikes
which exceed the insulation rating of most wires.  This becomes an issue in
wet areas and will cause insulation failure.  

There are other issues relating to inducing corrosion.  A friend who
coincidentally keeps his boat in RI and is the technical support guru for a
company that sells variable frequency drives (inverters for AC motors) had
to replace his propellers when he used an inverter he bought from Harbor
Freight.  It was probably fine for anything other than marine use. 

If the neutral on the inverter is not grounded, the neutral can kill you
regardless of the presence of a GFCI.  

Just my thoughts,

Ron Ricci
S/V Patriot
C 37+
Bristol, RI



 

 David via CnC-List <cnc-list@cnc-list.com> wrote: 
We have minimal inverter needs and would like to wire the 1000w inverter
directly to a dedicated outlet.  It does not have power outputs but two
receptacles for plugs.


I believe I can wire an extension cord to a outlet (assuming adequately
rated and quality components), but I would like to know of any pitfalls that
others may have found.


Thanks in advance.


David F. Risch
(401) 419-4650 (cell)



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make a contribution to offset our costs, please go to:  
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___

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make a contribution to offset our costs, please go to:  
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All Contributions are greatly appreciated!

Re: Stus-List Inverter to Outlet Via Extension Cord?

[Ron Ricci via CnC-List]

David,

I've followed some of this thread and have a few concerns where some have
mentioned using an inexpensive inverter.  

Using an inverter that is not intended for marine use or not properly
grounded can cause problems.  An inverter can produce short duration spikes
which exceed the insulation rating of most wires.  This becomes an issue in
wet areas and will cause insulation failure.  

There are other issues relating to inducing corrosion.  A friend who
coincidentally keeps his boat in RI and is the technical support guru for a
company that sells variable frequency drives (inverters for AC motors) had
to replace his propellers when he used an inverter he bought from Harbor
Freight.  It was probably fine for anything other than marine use. 

If the neutral on the inverter is not grounded, the neutral can kill you
regardless of the presence of a GFCI.  

Just my thoughts,

Ron Ricci
S/V Patriot
C 37+
Bristol, RI



 

 David via CnC-List  wrote: 
We have minimal inverter needs and would like to wire the 1000w inverter
directly to a dedicated outlet.  It does not have power outputs but two
receptacles for plugs.


I believe I can wire an extension cord to a outlet (assuming adequately
rated and quality components), but I would like to know of any pitfalls that
others may have found.


Thanks in advance.


David F. Risch
(401) 419-4650 (cell)



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make a contribution to offset our costs, please go to:  
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Re: Stus-List Inverter to Outlet Via Extension Cord?

[Steve Thomas via CnC-List]

Your basic "modified sine" cheap inverter has two hot connections, neither of 
which can be connected to ground. There is no "neutral". So long as you 
understand this, then ok. What it means is that if you connect to a single 
outlet as you describe, or to a string of outlets, what would otherwise be the 
neutral must not connect to the ground anywhere. Ever. 

Steve Thomas
C MKIII
Port Stanley, ON 

 David via CnC-List  wrote: 
We have minimal inverter needs and would like to wire the 1000w inverter 
directly to a dedicated outlet.  It does not have power outputs but two 
receptacles for plugs.


I believe I can wire an extension cord to a outlet (assuming adequately rated 
and quality components), but I would like to know of any pitfalls that others 
may have found.


Thanks in advance.


David F. Risch
(401) 419-4650 (cell)


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make a contribution to offset our costs, please go to:  
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Re: Stus-List Inverter to Outlet Via Extension Cord?

[Tim Goodyear via CnC-List]

Use a GFCI outlet at the least.

> On Oct 23, 2016, at 2:24 PM, David via CnC-List  wrote:
> 
> We have minimal inverter needs and would like to wire the 1000w inverter 
> directly to a dedicated outlet.  It does not have power outputs but two 
> receptacles for plugs.  
> 
> 
> I believe I can wire an extension cord to a outlet (assuming adequately rated 
> and quality components), but I would like to know of any pitfalls that others 
> may have found.
> 
> 
> Thanks in advance.
> 
> David F. Risch
> (401) 419-4650 (cell)
> ___
> 
> This list is supported by the generous donations of our members. If you wish 
> to make a contribution to offset our costs, please go to:  
> https://www.paypal.me/stumurray
> 
> All Contributions are greatly appreciated!
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Stus-List Inverter to Outlet Via Extension Cord?

[David via CnC-List]

We have minimal inverter needs and would like to wire the 1000w inverter 
directly to a dedicated outlet.  It does not have power outputs but two 
receptacles for plugs.


I believe I can wire an extension cord to a outlet (assuming adequately rated 
and quality components), but I would like to know of any pitfalls that others 
may have found.


Thanks in advance.


David F. Risch
(401) 419-4650 (cell)
___

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make a contribution to offset our costs, please go to:  
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