Hooking up an Inverter to a 110 Volt Breaker Panel

8 Posts
Jun 17, 2009 08:41 pm
Hooking up an Inverter to a 110 Volt Breaker Panel

I have had a solar system that was functioning well for about 7 years at my cottage. It consisted of a solar panel, some batteries, then an 1750 watt inverter that I plugged directly into a regular 110 household breaker panel. Recently when I started up the system, i heard a very high pitch noise, coming from the inverter. I assumed that was an alarm of some-sorts and quickly shut the system off.

I then went and bought new 1500 watt inverter. When I tried to plug , there was a huge flash emitting from the receptacle and the system was fried.

Any idea why the system did not work. One person tried to tell me that you need a special kind of an inverter to hook up to the house panel, as the negative on the panel is "bonded to ground".

I am not sure what this means, has anyone else had this problem of the inverter blowing up when trying to plug the 110 panel into it and what did they do to correct it. Is a special type of inverter required?

 
Jun 20, 2009 05:19 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Trouble shooting can sometimes be difficult and time consuming even when the trouble shooter is on location. To try and guess the problem over a written forum even more so.
Some inverters have an internal bond and some don't. What does the literature on your 1500 say about it? Could a lightning strike have damaged something else in you home, a load perhaps? Could there be reverse polarity at a receptacle or a dead short?
Its all a lot like being a detective. Sometimes you just have to eliminate all other possibilities, however unlikely, in order to find the culprit. A multimeter is a good tool to have. What you describe sounds like, power from another source finding it way back to the inverter, more than neutral being bonded to ground in more than one place. But there is really no way for me to know this obviously. Could a vdc wire be making contact with a vac wire somewhere? Chess in the dark.

You write that "negative" is bonded to ground in the panel. I associate;
"negative" to the battery vdc, (typically a black wire)
"neutral" to vac and, (typically a white wire)
"ground" to EGC or equipment grounding conductor bonded to a "ground rod" driven into the Earth. (typically bare and or green wire)

 
8 Posts
Jun 20, 2009 02:18 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Thanks Thomas for replying to my post.  I am having a big problem trying to solve this problem as it is at my cottage which is a bit remote and it is hard to find someone who wants to go up  and troubleshoot it.

Now i am being told that perhaps it is not grounded  (the 110 panel).I would like to clarify a bit. I was told by a a handy man that it was neutral bonded to ground and also that the 110 panel was not grounded.

So do I need one with an internal bond to wire to a house

One fellow tells me I need a special inverter that costs $2500, but the original one I had was only about $400 8 years ago , the current replacement for this one is $200. Are their inverters that are not made to be wired to a house 110 system. I am not really sure what to look for,

I have limited experience with electricity and have hired people to do the electrical wiring, they have  told me that there is nothing wrong with the panel  box to the 110 wiring, currently the solar panel charges 12 volt batteries and this also runs a 12v pump which works OK.  So it looks like the Solar panel to batteries are OK and the panel (to the 110 are OK, that leaves only the inverter (and the no ground business) but the old system worked before for many years with the alleged "no ground".

What do you mean power from another source finding its way to the inverter, since there is no other source of power except for the solar panels.

There as a lighting storm , the week of the failure, but I do not understand how that could affect the system now. I assume that a  lightning strike would just fry the current system, but I do not understand how it would affect the new inverter I wish to install.

My apologies for being so vague, as I understand very little about the system.










The biggest problem
 
351 Posts
Jun 21, 2009 06:39 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Mike:

You need to give us the make and model of your 1500W inverter. That will help clear up a number of things.  If you also tell us the make and model of the 1750W inverter, it will make it possible to really tell what the differences are.

Ken
 
8 Posts
Jun 22, 2009 07:02 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Thanks to all. I will be going up tothe cottage on July 1-5, so I will get the details on the inverters and get back to you.

 
25 Posts
Jun 22, 2009 08:39 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Is this cottage also hooked up to a power grid or just solar? It sounds like you just plugged the inverter directly into an already live power outlet, or am I reading this wrong?
 
8 Posts
Jun 22, 2009 10:01 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

No this cottage is not hooked up to the grid. The solar panel and batteries are the only source of power.
 
351 Posts
Jun 23, 2009 03:47 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

I think that we are going to find that Mike's 1500W inverter is an inexpensive half voltage scheme inverter.  And, his 110V panel is grounded, with the neutral bonded to ground in the panel.
So, when he plugged it in, he was pumping 60V into a direct ground. Flash, bang.

Half voltage schemes are a good reason that you should avoid plug in cords (power source) to a distribution panel. Although it is not as dangerous as a cord with male plugs on both ends, it is still a "suicide cord". If you want to use a distribution panel, make sure your inverter has connection terminals for a hard wire scheme.
 
Jun 24, 2009 04:16 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

What Ken describes makes sense, although the technology doesn't.
Assuming that its 12/2 with a ground Romex wire from the inverter to the panel, just for clarity, you're saying Ken, that these inexpensive half voltage scheme inverters are sending out half the voltage, 60 vac, on the black wire and the other half of, 60 vac, on the white wire and they come together in the load making the full 120 vac? (Which in Mike's case the white neutral wire is bonded to the bare grounded wire or EGC in his panel and 60 vac went to Earth and everywhere the EGC goes.) Yikes!

Would you tell us, what is the advertised trade name for this technology Ken?
I know there is; true sine wave, modified sine wave, and square wave inverters on the market.
How can someone know if they are buying an inexpensive half voltage scheme inverter?
 
351 Posts
Jun 24, 2009 11:01 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Thomas:

I wish there was an advertised trade name, or a requirement that they be plainly labeled as half voltage. 

Most of these used to be square wave, many are now modified sine wave. One of these days, I imagine they might even creep into the true sine wave. I haven't seen one yet, but they might exist.

Here are the Samlex FAQ's on grounding and bonding inverters. Numbers 10 and 11 are on point.
http://www.samlexamerica.com/customer_support/faq_06.htm

As far as telling them apart, I would treat any inverter that did not have hard wire terminals (receptacles only) as suspect, until proven otherwise.  Many have instructions that say the inverter is not to be wired to a distribution panel, plug in use only.  (But who reads instructions, anyway ??)
The ultimate test is a volt meter.

Ken
« Last Edit: Jun 24, 2009 11:13 pm by ken hall »
 
8 Posts
Jun 30, 2009 07:04 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

The inverter that I tried to install was an Xpower Inverter 1500 by Xantrex. It does not indicate anywhere in the manual that it can or cannot be installed and connected to a panel. The reason I tred it was that I had had a 1750 Watt Statpower inverter working well in this setup for 6 years (The 1750 was designed for an RV,so I figured (wrongly that any old inverter would do).

The system is not grounded as I found out that the electrician did not ground the panel, as the cottage is built on a rock. Would that be the problem, that it is not grounded properly. The old Statpower was never grounded.

I feel it may be something to do with the panel having a 'neutral bonded to ground. I do not fully understand this but I have been told that I could unbond the neutral to ground or bu an inverter with a 'floating neutral'


 
351 Posts
Jul 1, 2009 01:51 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Mike

Look on page viii, in the manual.
The second item under the Equipment Damage Caution.
"Do not connect any AC load that has its neutral conductor connected to ground to the XPower inverter."
The same warning is repeated on page 5-3.

While Xantrex could put that in language that might be clearer to everyone, that clearly indicates that they do not want it connected to a 110v electrical panel.

(not to mention that on page 1-1 they say "The XPower 1500 is a quality inverter designed for recreational vehicle
(RV) and truck applications.".)

Here is the Xantrex FAQ on the subject.
http://www.xantrex.com/support/readfaq.asp?did=253&p=1609


Your 110V system either has a ground or it doesn't. The normal place for it to be grounded is in the panel. The neutral bond is there.  But a ground anywhere on the 110V system (even to a metal water pipe) would make that neutral/ground bond active.  Without a ground somewhere, all you have is a neutral with extra metal in it.

(Whether or not you grounded the inverter chassis is a seperate issue)

Ken

 
10 Posts
Jul 1, 2009 08:34 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

This is all very familiar to me. I went through the same problems,blowing up a number of inverters.They were all Xantrex.First issue was the bonded ground.In a typical grid tie breaker panel,an electrician will put a jumper from the neutral wires (white) to the ground (bare) and connect to a ground rod. To test to see if you have a bonded ground, use an ohm meter and check at an outlet between the ground(round)and the larger (neutral)terminal, if 0 ohms, you have a bonded ground,you will need to remove the jumper. In my current off-grid cabin,I'm using a 1500 watt Xantrex inverter, with a two wire (no ground) connection to the breaker panel. The panel has all ground wires connected to the ground rod, driven in the ground.Works fine, however, that wasn't good enough for me. Next I thought I should ground the negative terminal of the battery, so I connected it to the same ground rod, and bang! another inverter gone. At this point I contacted the support folks at Xantrex. The answer was that they connot support this model of inverter hard wired to a distribution panel. If I require more outlets, use a power bar, distance use extention cords.They do have inverters i.E. TR series that support hard wire applications. So, here are my thoughts. I should remove the connection from the panel to the ground rod. Use a 3-wire connection to the inverter to the panel. In this way, it's the same as a power bar(multiple outlets) and increases distance(extension cords). Next ground the case of the inverter, which in turn grounds the outlet on the inverter as they are connected internally.So the outlets in the cabin, are grounded through the inverter. We think of the cabin, as an RV without any wheels, that the breaker panel is just a power bar with breakers, and the wiring to plugs and lights, just extention cords, I think we should be fine.
 
578 Posts
Jul 1, 2009 08:49 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

this is a good thread.  I hear about this all the time.  here are the main points i try to stress to folks

read the manual. seriously. 

  if you intend to use the inverter in a portable manner, then one with plugs is likely fine.

if you intend on having a permanent installation wired to a main service panel, select a "hardwire" inverter preferably listed to UL standard 1741 for renewable energy applications.  follow the NEC and use disconnects and overcurrent protection where necessary, and use conduit to keep prying hands out of places they dont belong.

also, for those implementing a hardwire inverter to an existing building that was wired for AC, make sure there are no multiwire branch circuits in the wiring.  when only providing a 120v source from an inverter, this may cause the neutral to be overloaded.

you may see inverters listed to the UL standard 458.  to the best of my knowledge, this is for mobile applications like recreational vehicles and boats.

hope that helps,

james
altE staff

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Tel: 877.878.4060 x107  or +1.978.562.5858 x107
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8 Posts
Jul 2, 2009 09:29 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Can anyone recommend n  low-priced inverter that would work in this situation. I looked up the TR series inverter and they were $900 each?

Anyone heard of an Floating neutral inverter , if so where could I buy one, I tried googleing it- no luck.

From reading the posts, I could also try Paul"s suggestion of treating the system as an extended power bar.

Unbound the neutral to ground
ground the system through the inverter

and use my xantrex system.

Would that be safe? 
 
578 Posts
Jul 2, 2009 09:36 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

900?

http://www.altestore.com/store/Inverters/Off-Grid-Inverter/1000-to-1999-Watts/Xantrex-TR1512-120-60-InverterCharger/p6671/

which model were you looking for?

james
altE staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 
351 Posts
Jul 2, 2009 07:47 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Mike:

The term floating neutral is often used to describe a system where the neutral is not bonded to ground.  Others also use it to describe two hot leads and a ground, with no neutral.

That is what the half voltage scheme inverter is. 60 volts on the hot, 60 volts on the “neutral”, and the separate ground wire.

The ground supplied by the inverter will probably be at a different ground potential than any other grounded item in the cabin (meaning water pipes or other conductive items with a direct path to earth.).  Between the different ground potentials and having 60V AC on your white wire (and other things that should be “neutral”), don’t be surprised if there are more shocks with this method.

Don’t count on protective devices to work properly.

You will never be able to interface it with a generator, or any other power source. (Other than running them through a charger to your batteries)

If you have fire insurance and the place burns, the insurance may not pay if the non-code system is discovered during the investigation.

Some people may point to a 230V system and say that the two hots and a ground have been used safely for years.  The difference there is the second hot is red and both hots are breaker protected. (And most homeowners are scared to death of 230V, won't get near the plug)
You would be using the whites as hots, without having breakers on them. That could easily start a fire, or cook your inverter.

Keep your panel grounded. It is much safer. Get a proper inverter for your system. 

Ken
 
10 Posts
Jul 3, 2009 10:06 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Just wanted to add a little background.My cabin is in an isolated location, and I must have 'portable" install. Have a problem with people helping themselves to your stuff. Last year they smashed a window and stole the woodstove, took 4 men to carry it in, not sure how many to remove it. Then they came back 2 weeks later and stole a truck load of firewood.The cabin was built with a lot of 2nd hand material, very low cost. So, although a proper hardwired $800 inverter might be the proper way to do it. Sometimes we have to make the best of what we have.
 
351 Posts
Jul 3, 2009 11:49 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

If you have to have plug in capability, I would use an appropriate sized SO cord between the AC panel and the inverter. If you install a 4 prong twist lock plug in the middle of it, you are now plug in capable.

Portability has nothing to do with the idea of unbonding the neutral, and putting 60 volts on it.
 
1 Posts
Jul 18, 2009 04:59 am
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

This thread answers questions that I've had for over a year on an installation that began with an AIMs 1250 inverter and has now progressed to a Xantrex Xpower 1750.  I now see that both of these inverters are of the half-voltage variety with hot neutral.  Amazingly, the AIMs operated for a year hooked to a bonded panel with the residents complaining that it wouldn't power appliances that I knew where within its watt capacity.  Somehow it struggled on with a virtual short between neutral and ground (I guess it had good current protection) and their appliances obviously didn't work too well at 60 volts.

Eventually the AIMS died, and now I've hooked up a Xantrex 1750 in the same config.  Amazingly, it too has not blown, but the residents of the cabin have similar complaints.  Thanks to this thread, and Ken, a light bulb (pun) has just gone on over my head.

Unfortunately, I still don’t think I can afford a hardwired inverter with a proper ground voltage neutral.  Does anyone know of one, even if it’s not a inv/charger combo that’s around $400?
 
8 Posts
Aug 7, 2009 07:36 pm
Re: Hooking up an Inverter to a 110 Volt Breaker Panel

Just a final report on my situation. I have located a "pure sine wave" inverter. It is an Eliminator brand sold by Canadian Tire in Canada for for $180 (on sale from $300). I called the company's 1-800 number and explained my situation and they said it should not be a problem to use it in my situation, that is plugged in to the house panel. I tried it and it now works.

Thanks to all for your advice and help!
 

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