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Inverter & Manual Transfer Switch
By Horseman, Section Controls Posted on Thu Jun 02, 2005 at 07:23:12 PM MST
I have a 120V Xantrex 1500W Inverter that I am trying to get to work with a manual transfer switch.

The MTS input is for a 4 wire receptacle (240 volt). I have tied the 2 hot wires together (X and Y poles) to make it 120 volt. I have the neutral (from the transfer switch) to the neutral bus bar in the load center and the ground to the common ground bus bar. I turn off all other power and when I plug into the 3 prong outlet on the inverter the fuses on the inverter blow. I have checked all my load connections and they are correct so I am thinking it is something to do with the ground or neutral. Any ideas greatly appreciated.

Inverter & Manual Transfer Switch | 10 comments (10 topical)

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#1)
by drdongle on Thu Jun 02, 2005 at 01:27:25 PM MST

Are you hooking it up according to the manual, can you post a diagram?
Carpe Vigor, Dr.D

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#4)
by Horseman on Thu Jun 02, 2005 at 02:01:42 PM MST

Yes doing the wiring from the transfer switch according to manual. Lines in to the transfer switch "in" wires (wire nuts), power lines out from switch to the individual breakers and the neutral to the neutral bus bar (load center) and the ground to the ground bus bar.

[ Parent ]

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#2)
by kurt on Thu Jun 02, 2005 at 01:46:17 PM MST

inverters use what is called a hot neutral you have to have a transfer switch that switches both the hot and the neutral. if you just tie all the neutrals together so that the neutral is still connected to earth ground at the breaker box the fuses on the inverter will blow

IRC
just a personal rant carry on.

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#3)
by Horseman on Thu Jun 02, 2005 at 01:57:19 PM MST

Any way around the hot neutral and the regular wiring of the transfer switch? Should I just not connect the neutral to the bus bar?

[ Parent ]

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#5)
by sandovalch on Fri Jun 03, 2005 at 07:05:56 AM MST

Remove the bar connecting the neutral to the ground in your main load center and make shure you have no other ground to earth connection. I have done this and my home runs happily with an inverter for 8 months now.
The neutral from the inverter is not really a neutral. If you take a voltmeter you will se about 55V from the chassis of your inverter to "neutral" and 55V from the chassis to "line". The voltage from "neutral to "line" should be 110V.

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#6)
by Horseman on Fri Jun 03, 2005 at 05:27:37 PM MST

Removing neutral to ground in the main load panel, won't this cause a safety hazard for when I turn on the AC or not? Appreciate everyones comments.

[ Parent ]

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#7)
by sandovalch on Mon Jun 06, 2005 at 04:30:24 PM MST

Sorry to reply so late.
I have done this, otherwise I would not have been able to run my inverter in my house. So far I've had no problem with any of my appliances in the house.
The earth bar remains the same and all the appliances connected to it remain connected to earth. The only thing you are changing is the connection from neutral to ground. In the case of the inverter you have not a neutral but a "live" signal with 55 Volts or so.
I change back from inverter to grid and have had no problems. The only thing you have to keep in mind is, if you do not integrate the whole house to the inverter, you must install a second load panel for all the appliances which will be running from grid. In that panel you'll have the neutral connected to ground.

[ Parent ]

Re: Inverter & Manual Transfer Switch (3.00 / 0) (#8)
by kflack on Sat Sep 17, 2005 at 01:02:02 PM MST

I am thinking of using a Xantrex 100W inverter and hooking it up to power all 110V appliances across my existing home wiring at the time of extended power failures.

My intent was not to use a Transfer switch but to manually turn off the main power breaker and hot wire a standard 110V plug from the inverter across the 2 input phases.

As the main breaker box has all neutrals tied to ground, it appears that this configuration, as described above would not function properly.

Doesn't Canadaina and U.S. wiring codes demand that neutral be tied to ground ?

I.E. Is my only legal option to install a transfer switch and a second power panel with isolated neutrals? Similarily doesn't this also break wiring code standards ?

Note: I have also read about Grid feed power panels where power is fed back onto the grid. Is there no groound connection to neutral in these installations ?

Would this problem be corrected if the inverter Negative battery terminal was grounded therebye establishing a ground reference for the inverter ?

Xamtrex Power Inverter 1000 (3.00 / 0) (#9)
by kflack on Sat Sep 17, 2005 at 04:52:27 PM MST

I have jsut read the entire book on my Xantrex Inverter and there is no mention of itolating the ground and neutral connections.

There is a reference to Ground the Xantrex power inverter box. (Chassis frame)

I also found annother reference on annother post that mentioned this configuration may work as long as there is no ground connected to the xantrex inverter. The risk being it would be floating at a higher potential and could cause a shock if touched.

So now I am really confused....

Next question.... Why are the ground and neutral lines tied together in a home wiring scenario anyways ?

Re: Xamtrex Power Inverter 1000 (Correction) (3.00 / 0) (#10)
by kflack on Sat Sep 17, 2005 at 05:34:23 PM MST

I went to their web site and this is their explanation of the Neutral (Issue)

This FAQ applies to Xpower, PROwatt, Portawattz, Jazz and Xantrex inverters, including the inverters integral to Powerpacks.
Your inverter is designed to have loads plugged directly into it and not be permanently connected to an AC distribution system. The fact that the inverter is not a permanent installation means the US NEC (United States National Electrical Code) doesn't apply, and the NEC is the main place where the requirement resides for single-phase 120Vac or 240Vac systems to have neutral bonded to earth. The US standard for inverters of this sort, UL458, does not have a requirement for a bonded neutral on the output of inverters.
Regarding the voltage that the you are measuring, the ground does not float halfway, rather the neutral is not at 0 volts. The grounding is correct, in that loads plugged in will have their chassis held at the same ground potential as the chassis of the inverter, but the neutral has approximately 60V on it instead of the usual 0V. The impact of that is minimal, since wiring and equipment connected to the neutral side of the circuit are required by safety standards to be treated as if they were at 120Vac. This is because there are many receptacles that are wired backwards or 2-prong plugs that are not polarized. As a result the 60V neutral is not accessible to the user, and any shock hazard presented is mitigated by lack of access.

The main safety agencies, CSA, UL, and ETL, have all approved inverters with this half-voltage on the neutral scheme, and the manuals contain warnings not to AC hardwire any of these inverters.

[ Parent ]

Inverter & Manual Transfer Switch | 10 comments (10 topical)

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