Earthing the inverter

[nofacey]

If you have shore power going directly into your boat via an extension cord, then you don’t have an isolation transformer or galvanic isolator and your boat is subject to being the sacrificial anode for the whole marina.
If it’s a metal hull, that can be the kiss of death, otherwise, those SS thruhulls (and whatever other underwater metal is grounded together) will be attacked.

Keeping your boat ground isolated from the marina is necessary to protect your boat, (and potentially any kid that dives in the water around it while connected to shore power - google ESD death)

[Ike]

Thanks to coopec43 and Gord May. It's nice to see that someone is still using my website. And this question by the OP is exactly why I wrote the page on The Connection Between Bonding, Grounding and Lightning Protection
https://newboatbuilders.com/pages/electricity14.html

[coopec43]

Originally Posted by nofacey

If you have shore power going directly into your boat via an extension cord, then you don’t have an isolation transformer or galvanic isolator and your boat is subject to being the sacrificial anode for the whole marina.
If it’s a metal hull, that can be the kiss of death, otherwise, those SS thruhulls (and whatever other underwater metal is grounded together) will be attacked.

Keeping your boat ground isolated from the marina is necessary to protect your boat, (and potentially any kid that dives in the water around it while connected to shore power - google ESD death)

Right now I have an extension cord to use shore power to run the fridge/freezer.

I expect the only power used in future on the yacht will be that generated from solar panels

[svmatilda]

When you do ground your inverter make sure the ground conductor and lugs are sized correctly.

Inverter Grounding

I am sure most of us know the high voltage of the AC system presents a shock hazard and can certainly be lethal. The DC system is not normally an electrocution hazard but can provide a lot of current, and so is potentially a source of fire. A suitable ground must be installed between the AC and DC system. During my inverter fitment I noticed in the operating instructions the requirement for grounding connections on both the AC side and DC side of the unit’s case. This grounding can prevent shocks from AC, and fire hazard from DC.

My previous unit only had the smaller AC grounding connection made. A fault in the DC side of the system could provide enough current to overheat the AC grounding conductor (think enough heat to melt insulation and start a fire) without blowing the large DC fuse. Keep in mind the fact that the AC ground is not fused and current will flow through the conductor until it burns out. A high amperage capacity DC grounding path back to the DC system should be made. The conductor size for the ground needs to be of sufficient cross sectional area (bigger is better) to be able to sustain enough current to blow the supply fuse.

The installation instructions for older inverters (as I had previously) typically do not include this precaution, but most newly designed units do. Though looking into some different manufactures install instructions this connection is not addressed in any depth, most only state or draw the connection in on the installation schematic. Due to the fuse size in my inverter we needed a 70 mm2 ground wire for the DC ground.

When using an inverter in the marine environment onboard, tests should be carried out after instalation to make sure the inverters electrical noise isn't enough to compromise reception on VHF frequencies used for radiotelephone, Digital Select Calling,(DSC) and Automatic Identification System (AIS)

[s/v Jedi]

Originally Posted by svmatilda

When you do ground your inverter make sure the ground conductor and lugs are sized correctly.

Inverter Grounding

I am sure most of us know the high voltage of the AC system presents a shock hazard and can certainly be lethal. The DC system is not normally an electrocution hazard but can provide a lot of current, and so is potentially a source of fire. A suitable ground must be installed between the AC and DC system. During my inverter fitment I noticed in the operating instructions the requirement for grounding connections on both the AC side and DC side of the unit’s case. This grounding can prevent shocks from AC, and fire hazard from DC.

My previous unit only had the smaller AC grounding connection made. A fault in the DC side of the system could provide enough current to overheat the AC grounding conductor (think enough heat to melt insulation and start a fire) without blowing the large DC fuse. Keep in mind the fact that the AC ground is not fused and current will flow through the conductor until it burns out. A high amperage capacity DC grounding path back to the DC system should be made. The conductor size for the ground needs to be of sufficient cross sectional area (bigger is better) to be able to sustain enough current to blow the supply fuse.

The installation instructions for older inverters (as I had previously) typically do not include this precaution, but most newly designed units do. Though looking into some different manufactures install instructions this connection is not addressed in any depth, most only state or draw the connection in on the installation schematic. Due to the fuse size in my inverter we needed a 70 mm2 ground wire for the DC ground.

When using an inverter in the marine environment onboard, tests should be carried out after instalation to make sure the inverters electrical noise isn't enough to compromise reception on VHF frequencies used for radiotelephone, Digital Select Calling,(DSC) and Automatic Identification System (AIS)

There is a lot of confusion about grounding aboard boats. To make a valid decision, one must first determine if their ship AC ground (where all the outlet ground conductors are connected) has a jumper to DC negative or not. Many older boats and most US boats will have this.

If this is the case, then the inverter chassis ground lug must have a ground wire to that ship AC ground which must be able to carry the current to blow the DC fuse for the inverter. Note that this can be a smaller diameter wire because you must match the ampacity of it with the fuse, while the DC cables are sized for voltage drop.

If you do not have DC negative connected to AC ground then you don’t need this. In that case you want to check with an ohm meter if the inverter chassis is internally connected to the AC ground terminals of the inverter output. If it is, then you don’t need this cable because the inverter output ground replaces it.

The reason that you don’t need a separate chassis ground cable for the second example is that AC does not provide a return path for DC (none of the AC conductors has a galvanic connection to DC negative).

[svmatilda]

Coopec I see your in Australia and I guess you have an AU registered vessel. Keep in mind your set up should be wired to the Australian standard. The AS/NZS 3004.2:2014 standard pertains to electrical installations in boats.

I am sure most people who read these forums will be amazed to find that the Australian/New Zealand Standard does not allow a galvanic isolator to be installed. (yep against the law and should some one die due to fitment of one then trouble awaits)

The other thing to find out for your safety is if the output (AC) of your brand of inverter is isolated from the input (DC). A lot of units on the market are basically aimed at the 4WD market and so the potential for problems on a vessel are manifested in the grounding. For additional safety you should also have a RCD fitted on the output but this may open up another can of worms for you. I do know there are plug in prewired kits with Circuit breaker and RCD combo but I am not sure whether they will work with your unit.

[coopec43]

Thanks for that.(I'll investigate)

The RCD I was planning to use is sold by Altronics.

https://www.altronics.com.au/p/p8143.../?gad_source=1

I'll have to be very careful to ensure three of them can fit side-by-side.

Would you have a problem with these RCDs?

[s/v Jedi]

Originally Posted by svmatilda

I am sure most people who read these forums will be amazed to find that the Australian/New Zealand Standard does not allow a galvanic isolator to be installed. (yep against the law and should some one die due to fitment of one then trouble awaits).

That’s interesting and I can understand reasons for that. I assume they do allow isolation transformers because I see no reasons for not allowing them.

[coopec43]

Originally Posted by svmatilda

Coopec I see your in Australia and I guess you have an AU registered vessel. Keep in mind your set up should be wired to the Australian standard. The AS/NZS 3004.2:2014 standard pertains to electrical installations in boats.

I am sure most people who read these forums will be amazed to find that the Australian/New Zealand Standard does not allow a galvanic isolator to be installed. (yep against the law and should some one die due to fitment of one then trouble awaits)

The other thing to find out for your safety is if the output (AC) of your brand of inverter is isolated from the input (DC). A lot of units on the market are basically aimed at the 4WD market and so the potential for problems on a vessel are manifested in the grounding. For additional safety you should also have a RCD fitted on the output but this may open up another can of worms for you. I do know there are plug in prewired kits with Circuit breaker and RCD combo but I am not sure whether they will work with your unit.

Thanks for your help.

Is this any use in determining the type of inverter/quality I have?

https://www.giandel.com.au/products/ps2000w-24v


https://www.manualslib.com/manual/26...Sine-Wave.html

[RaymondR]

Originally Posted by s/v Jedi

That’s interesting and I can understand reasons for that. I assume they do allow isolation transformers because I see no reasons for not allowing them.

It's never safe to assume logic, rationality or reason on the part of any bureaucracy in Australia.

[coopec43]

Originally Posted by svmatilda

Coopec I see your in Australia and I guess you have an AU registered vessel. Keep in mind your set up should be wired to the Australian standard. The AS/NZS 3004.2:2014 standard pertains to electrical installations in boats.

I am sure most people who read these forums will be amazed to find that the Australian/New Zealand Standard does not allow a galvanic isolator to be installed. (yep against the law and should some one die due to fitment of one then trouble awaits)

The other thing to find out for your safety is if the output (AC) of your brand of inverter is isolated from the input (DC). A lot of units on the market are basically aimed at the 4WD market and so the potential for problems on a vessel are manifested in the grounding. For additional safety you should also have a RCD fitted on the output but this may open up another can of worms for you. I do know there are plug in prewired kits with Circuit breaker and RCD combo but I am not sure whether they will work with your unit.

Thank you for your advice but I am confused when you mention "galvanic insolator"

What is a "galvanic isolator"?

Well I did a bit of research and found a whole lot of manufacturers (incl. Victron) make a little unit called Galvanic isolator




The purpose of these units is to stop corrosion when plugged into shore power

"The issue for boats plugged into shore power is that each one is electrically connected to every other one in the marina via the system's grounding conductor — the green wire. This creates a natural phenomenon known as the galvanic cell"

https://www.boatus.com/expert-advice...tors-explained.

I don't intend having Helen wired for 240V power so I assume I don't have to worry about Gavlanic isolation?

I would assume Galvanic isolation would reduce the effectiveness of grounding. Is that why it has been banned?

Right now I do have shore power coming to my yacht via an extension cord. In the event of an electrical fault in the the fridge/freezer I would hope the marina management have an RCD installed in their power outlet?. But I do have a short extension cord incorporating an RCD so to be on the safe side I should use that?..

Thanks for your advice.

[coopec43]

I came across this article which I found a big help.

The Connection Between Bonding, Grounding And Lightning

https://newboatbuilders.com/pages/electricity14.html

[Fore and Aft]

Coopec 43 I know nothing about inverter quality, but I use the specifications of a Victron Inverter as my gold standard. Your Giandel inverter 24/2000 weighs 4.5kg where the Victron weighs 24/2000 weighs 13kg. I imagine that is why there is a $600 price difference. Someone smarter than me will tell you what's missing.
Cheers

[coopec43]

Originally Posted by Fore and Aft

Coopec 43 I know nothing about inverter quality, but I use the specifications of a Victron Inverter as my gold standard. Your Giandel inverter 24/2000 weighs 4.5kg where the Victron weighs 24/2000 weighs 13kg. I imagine that is why there is a $600 price difference. Someone smarter than me will tell you what's missing.
Cheers

Yes some time ago an old guy with lots of experience said when it come to inverters the heavier the better.

But Giandel make heavy/expensive inverters too. Maybe they make them for 4WD/boats and then there are the ones used by tradesmen? Look at the one below 2000W/4000W 24V $1999. (Mine cost $350)

I know with welders they are rated by the % of time they can be used continuously.I've got a little one that I can easily throw into the boot of the car but you can only weld with it continuously for 3 minutes then you have to give it a rest. Some other young laughed at it when they saw it but who did they turn to when their dune buggy came apart.

[coopec43]

Originally Posted by Fore and Aft

Coopec 43 I know nothing about inverter quality, but I use the specifications of a Victron Inverter as my gold standard. Your Giandel inverter 24/2000 weighs 4.5kg where the Victron weighs 24/2000 weighs 13kg. I imagine that is why there is a $600 price difference. Someone smarter than me will tell you what's missing.
Cheers

The inverter in my house (for the solar panels) is 5600W and is massive. At a guess I'd say it weighs 35KG (The 2500W weighs 21.5KG)

That unit incorporates a MPPT type device which supplies power to the house and exports the remainder to the grid. (Very shortly the same unit will charge an L ion house battery as well)