AC disconnects?

[GlennWest]

On an inverter system should one have an AC volt disconnect at inverter out? Don't recall this being mentioned before but all the panels use them.

[Kirk W]

1 hour ago, GlennWest said:

On an inverter system should one have an AC volt disconnect at inverter out?

I'm not sure what you mean, but you should never have both the inverter and another source of 120V power connected to the same circuits at the same time, so if you mean a device to prevent that, the answer is yes. An RV that has an onboard generator always has a transfer device that opens one side before it closes to the other source. This should work the same way. 

[Sehc]

I have two outlets. One is fed by the inverter. A different outlet is fed from a 20 amp 'shore-line'. If you need a transfer switch, there are rotary switches such as these; https://www.bluesea.com/products/category/7/38/Switches/Rotary_Switches?Nominal_Voltage=120

[oldjohnt]

Glenn, (you're obviously already aware of the hazards of incorrectly tying multiple 120 VAC sources) sure, if you like you could install an AC disconnect on an Inverters output controlled however you like if safe and correct, but typically that's all handled by Transfer Switches. If plugged to shore power or a genset is running providing 120 VAC the Inverter isn't typically necessary so would be switched out of the circuit and the ONLY time you need to use your battery and Inverter to provide 120 VAC is when there's no shore or genset power available. While a person could install a disconnect on the Inverters 120 VAC output, there are plenty of alternative designs whereby such may or may not still be required.

I have seen rigs where the dude plugs his RV power cord direct into an Inverter,,,,,,,,,,Where critical circuits are served by a Sub Panel fed by an Inverter,,,,,,,,,,,Where manual or automatic transfer switches select between shore or inverter or genset 120 VAC delivery.

What IS REQUIRED is there be only one Neutral Ground Bond and Inverters can use relays to insure that.

One method I see and like is the Combination Hybrid pass through Inverter Chargers that have their own built in transfer switches.

There are all sorts of methods for connecting Inverters, Gensets, Chargers, Shore Power and safe selective switching and transfer and if an AC disconnect on an Inverters output remains necessary it's an easy install.  

NOTE an Overcurrent Protection device could be installed on an Inverters 120 VAC output to provide overcurrent protection PLUS used as a disconnect method if necessary or desired

      John T

[GlennWest]

Maybe I should have said more. My set up the entire camper will run from the batteries. Inverters hooked directly to main panel. Shore power will charge batteries only. I have a 50 amp main so should I have another before that? All the panels have a 30 amp disconnect. That is why I ask this.

[Barbaraok]

You're running air conditioning off of batteries?

[jcussen]

If your inverters are feeding a panel that includes all your electrical loads, should have a main breaker and breakers for each piece of equipment ie ac's, stove, cooktop, etc.. You can use this main breaker in the panel to secure the rest of the panel. Much like your house, except your inverters are supplying power instead of the grid.

Edited November 10, 2019 by jcussen

[Ray,IN]

1 hour ago, Barbaraok said:

You're running air conditioning off of batteries?

I think Glenn installed a Leaf battery bank with an enormous capacity,  covered the roof with solar.

[GlennWest]

yes, 21k kwh of leaf batteries, two or if needed 3, 4400 watts inverters, clean roof so cover with solar. 

[GlennWest]

3 hours ago, jcussen said:

If your inverters are feeding a panel that includes all your electrical loads, should have a main breaker and breakers for each piece of equipment ie ac's, stove, cooktop, etc.. You can use this main breaker in the panel to secure the rest of the panel. Much like your house, except your inverters are supplying power instead of the grid.

That is what I was thinking but all the panels have those 30 amp disconnects and had me doubting myself.

[oldjohnt]

Glenn, thanks for the updates, now that I better understand your question I can provide more guidance, here goes:

1) The main breakers in your AC distribution panels are well n good HOWEVER they only protect current and loads downstream and after them. They do NOT protect the wiring FROM the Inverter TO the panels. A short there would NOT cause the panels main breaker to trip, that fault current isn't flowing through the main breaker, get it ????

2) Typically an energy source, be it a Genset or an Inverter, have their own built in overcurrent protection to protect the component. I have no idea what kind of overcurrent protection or disconnect methods your Inverter currently has. I would suspect more along the lines of overcurrent protection versus any pure On/Off disconnect.

3) You DO need to protect the conductors FROM the Inverter TO the panels which may ?? be covered by the built in overcurrent protection device currently installed PROVIDED THAT its sized to protect the wire (Inverter to Panel) NOT sized only to protect the device. IE as an example (even if not realistic) if the equipment was protected at 100 amps but you had less then 100 amp rated wire (Inverter to panel) THE WIRE ITSELF ISNT ADEQUATELY PROTECTED. It wouldn't be good engineering to use wire having less ampacity then the Inverter can produce and, hopefully, the Inverter already has all the protection required.

4) Regardless, it wouldn't hurt to install fused disconnects or breakers that could serve as a disconnect method PLUS provide secondary overcurrent protection for the Inverter if you so choose.   A "Fused" Disconnect serves a dual purpose versus a disconnect only.

BOTTOM LINE you DO need to protect the wiring FROM Inverter TO Panel as the panels main circuit breaker ONLY protects what's downstream and after. If the Inverter has adequate built in overcurrent protection that can protect the Inverter and the wiring to the panel (See Para 3) fine. If in doubt, given the size of your system, if not already protected a breaker of fused disconnect might be a good safety tool.  

NOTE your Inverter may already have all the overcurrent protection and disconnect method built in, I just cant say from here.

Nuff said for now

John T

[jcussen]

4 hours ago, oldjohnt said:

Glenn, thanks for the updates, now that I better understand your question I can provide more guidance, here goes:

1) The main breakers in your AC distribution panels are well n good HOWEVER they only protect current and loads downstream and after them. They do NOT protect the wiring FROM the Inverter TO the panels. A short there would NOT cause the panels main breaker to trip, that fault current isn't flowing through the main breaker, get it ????

2) Typically an energy source, be it a Genset or an Inverter, have their own built in overcurrent protection to protect the component. I have no idea what kind of overcurrent protection or disconnect methods your Inverter currently has. I would suspect more along the lines of overcurrent protection versus any pure On/Off disconnect.

3) You DO need to protect the conductors FROM the Inverter TO the panels which may ?? be covered by the built in overcurrent protection device currently installed PROVIDED THAT its sized to protect the wire (Inverter to Panel) NOT sized only to protect the device. IE as an example (even if not realistic) if the equipment was protected at 100 amps but you had less then 100 amp rated wire (Inverter to panel) THE WIRE ITSELF ISNT ADEQUATELY PROTECTED. It wouldn't be good engineering to use wire having less ampacity then the Inverter can produce and, hopefully, the Inverter already has all the protection required.

4) Regardless, it wouldn't hurt to install fused disconnects or breakers that could serve as a disconnect method PLUS provide secondary overcurrent protection for the Inverter if you so choose.   A "Fused" Disconnect serves a dual purpose versus a disconnect only.

BOTTOM LINE you DO need to protect the wiring FROM Inverter TO Panel as the panels main circuit breaker ONLY protects what's downstream and after. If the Inverter has adequate built in overcurrent protection that can protect the Inverter and the wiring to the panel (See Para 3) fine. If in doubt, given the size of your system, if not already protected a breaker of fused disconnect might be a good safety tool.  

NOTE your Inverter may already have all the overcurrent protection and disconnect method built in, I just cant say from here.

Nuff said for now

John T

Very interesting John,  have had a bunch of coaches with inverters and inverter/chargers, and have never seen a disconnect or fuse between the inverter output and the main breaker in the panel. I guess some small very cheap walmart cigarette lighter plug inverters may not have any protection, but all the rv ones I have seen have breakers or internal fuses in the inverter on the output. The ones the OP is getting certainly do. But on the other hand, every inverter I have seen, has protection on the input, [12 volts or whatever] so that if the inverter tries to produce more power than it is capable of [a shorted output?], it will blow that fuse. The OP is asking all the right questions and think he will know the right size wiring to run from inverters to breaker boxes. 

 

 

 

 

[GlennWest]

It will be two Magnum MS4448PAE. And if needed 3. Got a price quote of 3400 including shipping for 2.

Edited November 11, 2019 by GlennWest

[oldjohnt]

5 hours ago, jcussen said:

Very interesting John,  have had a bunch of coaches with inverters and inverter/chargers, and have never seen a disconnect or fuse between the inverter output and the main breaker in the panel. I guess some small very cheap walmart cigarette lighter plug inverters may not have any protection, but all the rv ones I have seen have breakers or internal fuses in the inverter on the output. The ones the OP is getting certainly do. But on the other hand, every inverter I have seen, has protection on the input, [12 volts or whatever] so that if the inverter tries to produce more power than it is capable of [a shorted output?], it will blow that fuse

Good thoughts jc, Likewise, I've not seen auxiliary disconnects/protection installed on an Inverters output (don't mean they don't exist) and so long as they have their own internal overcurrent protection such that the device AS WELL AS the output wiring is protected NONE IS REQUIRED. I have no idea what the OP has so I figured no harm educating him.  Indeed, there needs to be protection on the input side to protect the inverter itself. And don't forget, the wiring FROM battery TO Inverters input needs protected which needs to be at the battery.

Nice sparky chatting with you jc

John T  Live from Walmart in Union City TN headed to Jonesboro Arkansas

[jcussen]

On 11/11/2019 at 3:24 AM, GlennWest said:

It will be two Magnum MS4448PAE. And if needed 3. Got a price quote of 3400 including shipping for 2.

Great price, am putting a 5200 watt system on the S&B, with leaf battery packs and need one. Mind telling us where you got that quote?

[GlennWest]

Sent you a pm

[GlennWest]

https://houston.craigslist.org/search/sss?userid=22176076