# grounding neutral

Q

#### Q

Jan 1, 1970
0
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

Q

D

#### Dale Farmer

Jan 1, 1970
0
Q said:
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

Q

The answer is, it depends. The manufacturers data with the thing should
have
some sort of diagram telling you how to connect it up to make a safe and
legal system. Get and follow their directions. The telling you that the
neutral
cannot be grounded makes me deeply suspicious about the quality and safety
of the unit, and I'd have someone who knows their way around inverters better
than I take a look at it.

--Dale

M

#### Mark or Sue

Jan 1, 1970
0
Q said:
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

I don't know if we have enough information to tell. Does this unit have a
grounding pin on its AC power outlets and if so how do they connect
internally to the inverter?. If the output is totally isolated from earth
ground, it is shock safe from ground faults but could be susceptable to
lightning strikes if connected to long wire runs. Since house distribution
systems are grounded (or more correctly must have their neutral and ground
wires bonded together), you will have limited use of this inverter if you
can't determine a way to ground the thing. I don't know why there would be a
difference between ground and neutral in an inverter...just where does
ground go that neutral can't?

B

#### Bill Kaszeta / Photovoltaic Resources

Jan 1, 1970
0
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

Q

I know that the Xantrex Portawattz line can not have the neutral grounded. I
smoked one last week. There is a hard to notice warning in the user
manual that the inverter is not to be connected to a wiring system with
a grounded neutral (grounded neutral is required by the USA National
Electrical Code). I thought that they were trying to avoid a situation with
dual neutral-ground bonds. Turns out that the AC is not isolated from the
DC input and that grounding the neutral when the dc is grounded causes
internal non-warranty damage. Send the unit in with $US 65 and they will replace it. This is also the reason the Portawattz line is not UL listed. Non-listed components should not be used in systems where the NEC applies. After calling/e-mailing all the smaller inverter manufacturers I found that except for the Coleman Powermate (PMP800), all other small inverters have this problem. Even the Coleman is not UL listed. I checked inside the non-functioning unit and there are no obvious burnt components. The basic dc/dc up converter (to 145 vdc) does not work and the integrated circuit associated with this conversion is totally unmarked. Unit is made in China. Therefore, I do not think you can use a low cost inverter as backup, but investigate the Coleman. Outpost.com has the 800W for about$US 70,
but the first unit I bought was dead on arrival.

Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
[email protected]

S

#### Scott Willing

Jan 1, 1970
0
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

Q

Are you talking about the wiring in your house? (I assume so, since no
inverter has an internal connection between AC output and ground.)

Are you entirely off the grid?

If so, you could disconnect neutral from ground at the AC distribution
panel in a pinch, hopefully temporarily. After all, being connected to
ground at the panel is what makes it "neutral" in the first place, and
much of the safety strategy is built around the assumption that this
connection exists. It is not a recipe for instant death or anything
(if it was, all those little car inverters would be slaughtering
people regularly) but I wouldn't leave things that way.

Using your Xantrex (or any non-isolated inverter) with the neutral to
ground connection broken and the DC negative input grounded, the
(former) hot and neutral AC terminals will both be at 60VAC with
respect to ground. So, e.g., the threaded connection of a lamp socket,
which should normally be at ground potential, would have 60VAC on it.
Equipment and circuits that are supposed to be turned off (switches or
panel breakers thrown) would still have 60VAC on their neutral
terminals. Like I said, not exactly instant death scenarios, but
certainly a lot less safe than normal.

FYI the real problem with non-isolated inverters isn't anything to do
with ground per se, the problem is connecting one of the AC output
terminals to one of the DC terminals by any means. It happens when you
ground both DC negative and AC "neutral" as in your house, but even if
you had a battery and your Xantrex inverter sitting apart from the
rest of the world on a rubber mat, and you connected "neutral" to DC
negative (or positive for that matter) with a wire, it would still let
the smoke out. Without isolation (transformer) between input and
output, any connection between the two is a no-no.

So back to the house - another option is to leave the neutral grounded
and lift the DC negative-to-ground connection instead. Then you have a
new twist - AC voltage with respect to ground on the DC terminals, but
hey, only when the inverter is actually running. The DC loads
shouldn't notice. I don't think.

Either solution is suboptimal IMHO, but in a pinch they will work. For
a temporary fix, I'd choose the former, i.e. leave the batts grounded
and lift the neutral.

Last thought - you could buy a honking isolation transformer that will
take the full output of the Xantrex (and then some - it will probably
get a little warm with all those unexpected harmonics) so you can
ground both ends of the inverter/transformer combination properly.
Then you've built yourself a fake Trace DR, with no charger.

Electrically it makes sense, economically it may not. Unless you get a
damn good deal on the iso-trans (not impossible at surplus, ham swap
meets etc.) that solution would be pretty silly compared to just
getting a better inverter with isolation built in.

-=s

M

#### Moebius Velcro

Jan 1, 1970
0
Q said:
I have a 1000 watt Xantrex inverter that I would like to use as a backup to
my 3000 watt Vector. The Vector works fine in my house with standard wiring
which includes a grounded neutral. The Xantrex on the other hand says the
neutral cannot be grounded. I let the smoke out of a smaller inverter when I
plugged it into the house wiring with a grounded neutral.

My question is:

Is it safe to disconnect the neutral from ground?

There ought to be a ground on the system _womewhere_ and any system that
floats is trash.

;B