Connecting outlets to mobile inverters

[GeorgeF]

In another thread we can read about mobile inverter as per attached screenprint.

In a house not connected to the grid, I can connect an outlet to the (gfci)receptacle of a small cheap 12v 150w MSW junk-toy-mobile-inverter, perhaps also connect a second outlet in another room.

It then enables me, with adequate fusing between the battery and this inverter, to load for example a 25w led TV , some leds and to charge some gadgets, all ac-powered total let's say <= 85w.

No grounding whatsoever needed, the connected outlets also do not need ground and no fuses or mcb's needed between the AC-output of this inverter and the loads.

My question is if every evening the inverter runs <= 6 hours:

Can the above simple setup considered to be safe and does this simple setup in the USA comply with NEC?

[chrisski]

If you’re asking if Sunking’s advice is in compliance with NEC code, then I would say I doubt it. I don’t know though; I’m not an electrician. When I try to access NEC code for my questions, I can’t because its pay to view.

I would not take any advice on whether or not its IAW NEC code off a forum. That is different that Sunking’s answer about whether its safe or not.

The only thing I see wrong about what you’re asking, which I think is, “Can I hardwire a 100 watt inverter to two different 120 volt, 15 amp AC outlets in an off grid situation so I can use them for 85 watts instead of the fulll 1800 watt outlet rating?” Is what happens when someone sees a plug and plugs in his 1700 watt kettle to boil his water. Not sure how that inverter would handle it. THere’s some good videos on YouTUbe of inverters bursting into flames.

I built my system, so I know the limitations and would never do anything like that, but the three other people that use this system always seem to find a new and different way to exceed the limitations. Things like that is why over 150 years of electricity use the NEC code was developed to prevent accidents like that.

[GeorgeF]

It can also be an extension cord with some sockets and not a specific wall-outlet.

BTW, in a small house with no grid connection there will be no appliances of 1000w+ ..

Anyway, according to manual there is an overcurrent protection. It must trip then ....

[GeorgeF]

Ofcourse I understand that most of you are pro's and consider such a cheap mobile msw inverter as "junk".

Im just wondering what is the best and safest way to use such an inverter if you want to load more than one low wattage ac-powered appliances.

[chrisski]

I’d just put a two prong plug or multiple outlet power strip. Just make sure its a very low wattage charger as in not two quick chargers at once. You can have voltage loss even on AC so don’t be surprised if there’s problems on a long run to a different room with this inverter.

[GeorgeF]

I’d just put a two prong plug or multiple outlet power strip. Just make sure its a very low wattage charger as in not two quick chargers at once. You can have voltage loss even on AC so don’t be surprised if there’s problems on a long run to a different room with this inverter.

So, this means that more than 1 ac-powered non-inductive appliances can be "safely" loaded with a cheap msw inverter with one receptacle. As per above example max 85w with a 150w msw inverter or 120w with for example with a 200-300w inverter connected to two outlets.

The cable will be as short as possible to the second outlet, < 2 meter from the 1st outlet.

[SunEagle]

It can also be an extension cord with some sockets and not a specific wall-outlet.

BTW, in a small house with no grid connection there will be no appliances of 1000w+ ..

Anyway, according to manual there is an overcurrent protection. It must trip then ....

IMO all of those small inverters should only use extension cords for each load and not connect to a receptacle.

[chrisski]

So, this means that more than 1 ac-powered non-inductive appliances can be "safely" loaded with a cheap msw inverter with one receptacle.

If you want safe just plug into the inverter. Take no other advice from a stranger who is not an electrician and has never seen the unnamed inverter nor the two loads you are trying to charge.

Is it NEC certified safe? I don’t know but I doubt it. Would I try it? Yes, but I also would read the specs of the inverter and make sure by far that I am well under the load.

Is that safe? I’m not licensed to say so.

[Bala]

I have 600w psw inverter I use in my Ute and caravan. It is an RV type reasonable? quality. I have it only for things I don't have dc chargers for. It has one outlet and I plug in an extension lead and 4 outlet power board and run multiple things off the power board outlets. So yes you can run multiple things off the one outlet.

It is a 600w inverter and I have a 30a breaker on its dc input to limit output. This will prevent anyone overloading the inverter and still give me ample ac wattage for what I need.

It is a floating system so no grounding.

Would it be nec approved, I have no idea.

Is it as safe as possible, in a mobile application possibly. But in a house you could have an inverter set up with grounding and rcd protection like my house is, so that would be a safer option.

[SunEagle]

I have 600w psw inverter I use in my Ute and caravan. It is an RV type reasonable? quality. I have it only for things I don't have dc chargers for. It has one outlet and I plug in an extension lead and 4 outlet power board and run multiple things off the power board outlets. So yes you can run multiple things off the one outlet.

It is a 600w inverter and I have a 30a breaker on its dc input to limit output. This will prevent anyone overloading the inverter and still give me ample ac wattage for what I need.

It is a floating system so no grounding.

Would it be nec approved, I have no idea.

Is it as safe as possible, in a mobile application possibly. But in a house you could have an inverter set up with grounding and rcd protection like my house is, so that would be a safer option.

As long as the wires between the battery and inverter are properly sized and fused (600w / 12v = 50 amps) then you should be ok.

[GeorgeF]

Resumé:
as long as there are adequate wiring & fusing between the battery and inverter , you can load more than 1 non-inductive load with a cheap msw inverter, for example with an extension cord with some AC- sockets.

No grounding whatsoever needed and no fusing at the ac-load side. The inverter has all the protection needed.

After reading other threads here, as far as I understood NEC have no jurisdiction for mobile aplication in for example campers. So using in a house with no grid connection in the USA as per above example and an inspector come to inspect he can not disapprove such a simple setup similar as in a camper. Correct?

[Bala]

Suneagle, yes the cable would handle the 1200w peak of inverter but there is no need or want to draw even what I have fused it at. The only reason I am using this inverter is that it came with the Van otherwise I would have purchased a smaller one. All it has to do is charge a couple of head torches that I dont have DC charge leads for, electric toothbrush and my laptop. The two head torches and toothbrush together are only about 20w maximum and the laptop about 80w.

George F,

I am happy that how I have set up my caravan and use my system it is as safe as can be for a mobile application and never has A/C running while mobile.

I dont know what inverter you have or looking to buy or what you will plug into it. At the end of the day you are still using A/C power that is dangerous.

I certainly cant confirm that what you want to do will be safe or whether NEC have any authority.

[GeorgeF]

George F,

I am happy that how I have set up my caravan and use my system it is as safe as can be for a mobile application and never has A/C running while mobile.

I dont know what inverter you have or looking to buy or what you will plug into it. At the end of the day you are still using A/C power that is dangerous.

I certainly cant confirm that what you want to do will be safe or whether NEC have any authority.

just any non-UL listed 12v inverter <= 300w with overcurrent protection, built-in fan and will trip when overheating, and the receptacle works like gfci enabling to load some non-inductive loads , preferably with built-in switch to turn the inverter on/off.