All-in-one MMP system manual says: AC breaker must be installed, but nobody installs it?

[sepiot]

Hi
I have one of these hybrid MMP inverters (see specs below), which I intend to use in an outbuilding that has also access to grid electricity (AC Input). I have seen a few install videos on you tube (including Will Prowse's) and all of them use (half) an extension cord to connect directly into the wall socket for AC Input.
However the manual states:
'CAUTION!! Before connecting to AC input power source, please install a separate AC breaker between
inverter and AC input power source. This will ensure the inverter can be securely disconnected during
maintenance and fully protected from over current of AC input. '

I live in the UK (but this should not make any difference, should it?), and when I suggested connecting directly with an extension cable, I got this answer in a uk forum:
'An inverter cannot be connected via a plug and socket, as if unplugged the pins of the plug will remain live until the inverter detects the loss of AC and shuts down.
If a fault occurs on the AC circuit it's connected to, the protective device will disconnect the AC within the required time, but that circuit will remain energised until the inverter detects the AC loss, which will result in the required disconnection times not being met.
Hard wired into it's own dedicated circuit is the only option.'

Is this true? Was there a misunderstanding on the type of inverter/system? And in any case, why is everybody on you tube ignoring the manual?

Also, there is the matter of grounding the inverter. Manual says:
'GROUNDING INSTRUCTIONS -This inverter/charger should be connected to a permanent grounded
wiring system. Be sure to comply with local requirements and regulation to install this inverter.'

I have seen Will's video about this, and to be honest I don't understand many of the technicalities. I can see how a ground loop could be a big risk, and when asking around, people tell me the best thing would be use the same ground as the main electricity supply/grid, but this has its own logistic challenges, and I'd rather install a separate ground. What are the option? I am happy to get a qualified electrician, but I also think that this does not seem to be a black & white thing, but rather a matter of interpretation, probability, and risk management, applied to each specific case. I have read different opinions from qualified people online about this particular system, so I'd like to have a bit of info before calling an electrician who may have never face this particular set up.

System:

• 4 x 300W solar panels
• MMP (Iconica in UK) Hybrid 3000W 24V pure sine wave inverter
• 6 x 100Ah AGM deep cycle Photonic Universe leisure batteries

 

[Revelation]

As far as Will's videos when he hardwires an electrical plug into the AC side of an inverter there are a couple of things to keep in mind...

#1: The outlet itself is grounded and he uses a three prong plug which has a ground (in the US)
#2: The outlet will, itself, be wired into an AC breaker

 

[Rednecktek]

As far as Will's videos when he hardwires an electrical plug into the AC side of an inverter there are a couple of things to keep in mind...

#1: The outlet itself is grounded and he uses a three prong plug which has a ground (in the US)
#2: The outlet will, itself, be wired into an AC breaker

#3: He's demonstrating in a limited camera angle view.

All the installs I've seen, be them cabins or RV's or such, have always fed the outgoing AC into a breaker in the panel to feed the legs. The power cord is really only an option on some really small portable systems that don't have a breaker box to feed and it just goes straight from the terminals to a power strip.

 

[sepiot]

Aside from my house Circuit breaker panel (which is grounded as per UK regulations), the outbuilding where the inverter is being installed has its own AC breaker 'box'. So the AC outlets in the outbuilding are connected to this AC breaker, which is itself connected to the house AC breaker (and grid), which is grounded as per UK regulations.
So as I understanding it:
#1 Yes, also in the UK
#2 Yes, the AC breaker in the outbuilding
#3 So does my system, justify a hard wired AC breaker, or is it small enough for a extension cord?

 

[Rednecktek]

#3 So does my system, justify a hard wired AC breaker, or is it small enough for a extension cord?

Breakers are cheaper than fires, plus it lets you disconnect the circuit.

So the AC outlets in the outbuilding are connected to this AC breaker, which is itself connected to the house AC breaker (and grid),

Please don't try to feed your breaker panel from the grid AND the AIO at the same time, it's a Very Bad Thing!

 

[mrzed001]

About grounding ... There is only one Earth !
(I know, double meaning ? )
All your equipment's have to be connected to it. Also the Equipotential bonding.

The big question is: does your inverter have a PE-N relay ?
You can test is easily. Connect only PE on AC_in side. Use inverter from battery. AC_out some load.
And now check the Volt values between PE and L. Also between PE and N.
If PE - N is not null (like 100+V) then there is no PE-N relay in the inverter.
You have a floating ground.
Easiest solution is to connect AC_in_N to AC_out_N (common neutral solution).
Much better is with an outer PE-N relay if inverter has a working Dry Contact port (external PE-N relay solution):

Search: 20 results found for "off grid inverter grounding tns"

Manufacturer of Solar Photovoltaics Systems and Premium LED Lights since 2011. We design and develop small and medium scale energy systems for off grid electrification. Buy components online today.

voltaconsolar.com

 

[Zil]

I often see confusion in questions about connecting inverters. An Inverter (.) changes DC into AC current. A Converter (.) changes AC into DC current. AKA a Charger.
Never use an extension cord Male Plug to connect an invertor's AC output into a AC female socket as you find in the wall of a S&B.
There are combination devices that Invert as well as Convert. If the power requirements of the input AC is within the extension cord's capacity plugging into the AC outlet will be protected by the building circuit breaker and earth ground.

 

[Cheap 4-life]

Outlets fail often, I’ve replaced many for customers. I would never use an outlet for an inverter. Hardwiring them is a much better idea. Even simply using the outlet box instead as a junction box is better than using an outlet..

 

[2Vets]

I believe many of Will's videos are for demonstration purposes. Recepticals here in the use are 15 or 20 amps and are already on a breaker in the main panel.
It is best to wire to a breaker, see what size is called for in manual for the particular AIO unit you have. Have the correct wire size for the max input amps also.

If you are talking about output the same applies, run wires to a breaker in the panel you will use from your AIO.

Bonding is the big thing between the 2 with AIO. If connected to AC power then if it does not have the ability to auto flip over to unbonded then you will need to do that. Ground and Neutral are bonded in the US at the meter on the norm or so I've been told. I know my panel is grounded to a grounding rod and the ground and neutral are not bonded.

 

[Cheap 4-life]

I believe many of Will's videos are for demonstration purposes. Recepticals here in the use are 15 or 20 amps and are already on a breaker in the main panel.
It is best to wire to a breaker, see what size is called for in manual for the particular AIO unit you have. Have the correct wire size for the max input amps also.

If you are talking about output the same applies, run wires to a breaker in the panel you will use from your AIO.

Bonding is the big thing between the 2 with AIO. If connected to AC power then if it does not have the ability to auto flip over to unbonded then you will need to do that. Ground and Neutral are bonded in the US at the meter on the norm or so I've been told. I know my panel is grounded to a grounding rod and the ground and neutral are not bonded.

Ground and neutral busbars should always be bonded in the main/first panel after the service drop. Also ground/neutral should be bonded in either the electrical meter or at the weather head but not at the electrical meter and the weather head

 

[2Vets]

Ground and neutral busbars should always be bonded in the main/first panel after the service drop. Also ground/neutral should be bonded in either the electrical meter or at the weather head but not at the electrical meter and the weather head

All I know is when my old home had an upgraded service done, by a friend of mine Business owner Master Electrician and myself. the ground and neutral NOT bonded in the panel but was at the meter, the ground removed from copper water line to new ground rod exterior of home. Over 20 years ago but that was code here then, passed inspection and all.

edit: Oh he did run wiring in from meter to a neutral busbar then a jumper over to the second bus bar. The Ground Neutral from meter base, and Ground from inside all attach at the same ground rod.

 

[sepiot]

Breakers are cheaper than fires, plus it lets you disconnect the circuit.


Please don't try to feed your breaker panel from the grid AND the AIO at the same time, it's a Very Bad Thing!

Sure, the only thing is that I can DIY an extension cord to connect to an existing power outlet, but not sure if I should install an AC breaker myself. Could I use the same cable that feeds the AC outlet and put an AC breaker instead? I'll have to do some research, or just call an electrician...

And not sure what you mean about feeding the AC breaker from both sides? I wouldn't know how to do it anyway. The AC breaker will have to be connected to the grid, otherwise there is not electricity and no point to the AC input on the AIO. And the AC breaker surely is also connected to the inverter's AC input (of course, not the AC Output!). So it is connected to both, but not 'fed' from both, if that's what you meant...

 

[sepiot]

About grounding ... There is only one Earth !
(I know, double meaning ? )
All your equipment's have to be connected to it. Also the Equipotential bonding.

The big question is: does your inverter have a PE-N relay ?
You can test is easily. Connect only PE on AC_in side. Use inverter from battery. AC_out some load.
And now check the Volt values between PE and L. Also between PE and N.
If PE - N is not null (like 100+V) then there is no PE-N relay in the inverter.
You have a floating ground.
Easiest solution is to connect AC_in_N to AC_out_N (common neutral solution).
Much better is with an outer PE-N relay if inverter has a working Dry Contact port (external PE-N relay solution):

Search: 20 results found for "off grid inverter grounding tns"

Manufacturer of Solar Photovoltaics Systems and Premium LED Lights since 2011. We design and develop small and medium scale energy systems for off grid electrification. Buy components online today.

voltaconsolar.com

Thanks for this, but at the moment I don't know the answer to the 'big question', and the system is not at the stage where it can be tested the way you suggest. I'll also need to 'decode' some of the technical stuff you mention. I'll keep it mind though...

 

[sepiot]

I often see confusion in questions about connecting inverters. An Inverter (.) changes DC into AC current. A Converter (.) changes AC into DC current. AKA a Charger.
Never use an extension cord Male Plug to connect an invertor's AC output into a AC female socket as you find in the wall of a S&B.
There are combination devices that Invert as well as Convert. If the power requirements of the input AC is within the extension cord's capacity plugging into the AC outlet will be protected by the building circuit breaker and earth ground.

I don't think this applies here? I was talking about connecting the inverter's AC input, not the output. From some replies heres, it seems clear that an AC breaker is the way to go anyway.
Although actually, I was planning using a female extension cord on the AC output, so that I c an connect regular appliances. Is this a problem too?!!

 

[sepiot]

Outlets fail often, I’ve replaced many for customers. I would never use an outlet for an inverter. Hardwiring them is a much better idea. Even simply using the outlet box instead as a junction box is better than using an outlet..

Ok, I get the message. So the question is, is this a DIY job? I guess as long as I get the breaker with the right specs it should be easy enough? Not sure if I could use the same cable that feeds the wall outlet, and just replace the outlet for the AC breaker? Or would I have to replace the cable as well ?

 

[sepiot]

I believe many of Will's videos are for demonstration purposes. Recepticals here in the use are 15 or 20 amps and are already on a breaker in the main panel.
It is best to wire to a breaker, see what size is called for in manual for the particular AIO unit you have. Have the correct wire size for the max input amps also.

If you are talking about output the same applies, run wires to a breaker in the panel you will use from your AIO.

Bonding is the big thing between the 2 with AIO. If connected to AC power then if it does not have the ability to auto flip over to unbonded then you will need to do that. Ground and Neutral are bonded in the US at the meter on the norm or so I've been told. I know my panel is grounded to a grounding rod and the ground and neutral are not bonded.

This is helpful ,thanks.

The thing is that it is not just Will's videos. I have seen several other installations from different people that use extension cords for both AC input and AC output. Odd!

I would need a 32A AC breaker for the AC input of my system, according to the manual. I thought the AC output would be ok without a breaker (manual says nothing on this, whereas it recommends one on the AC input). I'd need to find out the specs for this one.

As for the cable/wire size, the existing cable to the wall socket can surely cope with any domestic appliance, so should it not be able to equally cope with the inverter's electricity draw? Or do you mean the cable between the AC breaker and the inverter? I'll check the gauge is fit purpose of course.

I'll have to check UK regulations regarding grounding, bonding etc. And it is something I'll surely ask my local electrician eventually...

 

[Bud Martin]

'MMP (Iconica in UK) Hybrid 3000W 24V pure sine wave inverter'
" I would need a 32A AC breaker for the AC input of my system, according to the manual."
Can you provide us the user manual and the spec of the unit?
You are in UK which is 230VAC 50Hz system, so 32A breaker does not sound right for 3000W system.

 

[Steve_S]

I use Dual VAC Input Inverter/Charger (Tier-1 Samlex). 1 AC Line is for Grid Supplied, 2nd AC line is for genset AC.
Each AC Line per spec must have an appropriately sized AC Breaker BEFORE entry to the Inverter.
The AC Line Out also goes to a Breaker and then to the Subpanel feed.
This is all per Manufacturer specs and Samlex is extremely well documented for all scenarios and possibilities.

I have installed several and helped design many systems. These are all Non-Mobile systems. 1st Lesson Learned long long ago, NEVER EVER trust any breakers supplied within equipment, a proper High Quality breaker is the correct solution.

I see the "Extension" cord thing and it makes me shudder, even when it is just for a quick visual, some folks get the wrong idea and believe such is acceptable which it is NOT. Not one single solitary Electrical Inspector would ever allow that to pass in any way. BTW: Some Electrical Inspectors WILL look for input & output breakers between the Inverter/Charger/AIO and will insist on such.

Hope it helps, Good Luck

 

[Cheap 4-life]

Ok, I get the message. So the question is, is this a DIY job? I guess as long as I get the breaker with the right specs it should be easy enough? Not sure if I could use the same cable that feeds the wall outlet, and just replace the outlet for the AC breaker? Or would I have to replace the cable as well ?

You could remove the outlet and put a pass thru cover on it. That will allow the inverters wire to be wire nutted or wago connected inside the outlet box which is now a junction box. I would make sure there’s no other loads that are getting their power from the circuit the inverter is connected to. Most of the time 12gauge is used for outlets (possibly 14gauge) so make sure that’s thick enough for your inverters output.
Just read you need 30+ amps to go thru the inverters wires. You will need at least 10awg wire so you will probably have to run wire from the inverter directly to a 30+ amp breaker. If you havnt done it before than an electrician will assist you

 

[Zil]

I don't think this applies here? I was talking about connecting the inverter's AC input, not the output. From some replies heres, it seems clear that an AC breaker is the way to go anyway.
Although actually, I was planning using a female extension cord on the AC output, so that I c an connect regular appliances. Is this a problem too?!!

Don't hard wire anything into the circuitry of your S&B !
You already have a breaker on the outlet of a S&B if that is what you are plugging the charger into. An additional breaker is not needed but will not exactly hurt. Breakers and fuses protect wires, not equipment. Some devices have internal fuses. Those protect the wires inside the device.
Using an extension cord on the inverter outlet is fine as long as the cord can handle the required power over the distance needed. I do that with my Microwave in the camper.