Step down transformer for isolation on boat.

[Bowdrie]

In an isolation transformer the neutral and ground/green wire are connected together on the secondary side only.
The secondary side now becomes the "Source" of the power", NOT the shore side.
Those two conductors, (secondary side,) are now the "Conductors/Resisters in Parallel" which if there is an imbalance in the flow between hot and neutral will trip the RCD which is installed between the secondary and your AC panel.
You should also have an RCD between the shore power inlet and the isolation device.
Your "shore power" whether it be at the dock, or an extension cord leading to the boat on the hard should have a GFCI breaker also.
At any rate, please use RCDs/GFCIs.

[s/v Jedi]

That said, the NEC also recognizes isolation transformers and even ungrounded networks. This is assuming that hospitals, clean rooms etc. are all conforming to code.

[goboatingnow]

Originally Posted by ItDepends

Jammer,



Thank you for understanding my question and re-articulating it in a more technically coherent form.



I certainly did not mean to suggest that there were inspectors wandering around the boatyards looking for boats not properly grounded. It's just that given a choice, I prefer to follow the codes because they have been refined over the years to consider an awful lot of unusual cases.



I can follow standards very well, and certainly have enough understanding of electricity on a practical and theoretical level to be able to understand all the everyday issues that come up. But I do rely on the standards organizations be it ABYC or NEC to think deeper about those oddball cases that are not normal and can cause unexpected problems.



In general, I find that people who blow off the standards organizations are not really impressing me with their clear thinking. "I know better than all those idiots on the expert committee..." Yeah--maybe...

Yes but the fact is standards organisations and codes are different around the world hence such codes merely represent “ locked in thinking “ I like to review many standards and think through what’s really being attempted. Nec As has ABYC traditionally ignored the safety advantages of whole house or boat 30 mA RCD safety. This is not a good approach.

[goboatingnow]

Originally Posted by Bowdrie

In an isolation transformer the neutral and ground/green wire are connected together on the secondary side only.
The secondary side now becomes the "Source" of the power", NOT the shore side.
Those two conductors, (secondary side,) are now the "Conductors/Resisters in Parallel" which if there is an imbalance in the flow between hot and neutral will trip the RCD which is installed between the secondary and your AC panel.
You should also have an RCD between the shore power inlet and the isolation device.
Your "shore power" whether it be at the dock, or an extension cord leading to the boat on the hard should have a GFCI breaker also.
At any rate, please use RCDs/GFCIs.

Absolutely it’s a huge failing of NEC and ABYC to recognise the values of whole house and whole boat 30mA RCDBO protections. It has lead to the water electro shock issues utterly missing in other parts of the world ( with higher voltages ) and has lead to ABYC bonding practices as a result that encourage underwater corrosion.

[CharlieJ]

@goboatingnow:
Please stop spreading these half truths:

As has ABYC traditionally ignored the safety advantages of whole house or boat 30 mA RCD safety.

ABYC changed the applicable Standard regarding RCDs about 8 years ago. Implementation was delayed one year waiting for US manufactures to manufacture a whole boat RCD (ELCI) that would not nuisance trip.

[s/v Jedi]

Originally Posted by CharlieJ

@goboatingnow:
Please stop spreading these half truths:

ABYC changed the applicable Standard regarding RCDs about 8 years ago. Implementation was delayed one year waiting for US manufactures to manufacture a whole boat RCD (ELCI) that would not nuisance trip.

This is true, but it was about 20 years after the rest of the world. It demonstrates how slow ABYC is and it’s the same with the lithium batteries now. The current guidelines would have been okay 10 years ago and should have been updated for LiFePO4 shortly after, at least 5-6 years ago.
The way they function now is not in the interest of the boat owner, just in the interest of the marine industry and to keep legislators quiet.

[goboatingnow]

Originally Posted by CharlieJ

@goboatingnow:
Please stop spreading these half truths:

ABYC changed the applicable Standard regarding RCDs about 8 years ago. Implementation was delayed one year waiting for US manufactures to manufacture a whole boat RCD (ELCI) that would not nuisance trip.

Yet Europe has such devices on the Market at fractions of “ELCI “prices for two decades previously. Totally a case of “ not invented here “ there was zero need to make “ custom ELCI “ when a whole industry of suitable RCBOs were available and fitted to European boats for decades.

I stand by everything I said. The lack of comprehensive. Rcbo On marina pillars is testimony to the NEC incompetence and exposure of whole groups of swimmers to electro shock risk. A situation almost unheard of in Europe.

ABYC then tried to overcome NEC limitations by subjecting US boats to bonding systems that had nothing to do with corrosion prevention and everything to do with NEC code limitations.

[CharlieJ]

s/y Jedi

The way they function now is not in the interest of the boat owner, just in the interest of the marine industry and to keep legislators quiet.

You couldn't be more wrong.

[CharlieJ]

@goboatingnow

ABYC then tried to overcome NEC limitations by subjecting US boats to bonding systems that had nothing to do with corrosion prevention and everything to do with NEC code limitations.

That is not the timeline. You could not be more wrong.

[s/v Jedi]

Originally Posted by CharlieJ

s/y Jedi

You couldn't be more wrong.

Really? Why do you only quote a tiny part then? Is that the only part that is wrong in your opinion, while all the rest is correct? That would mean you would have to say I am mostly correct right

So explain how delaying RCBO’s for 20 years and now making it impossible to install an isolation transformer to their guidelines, or using LiFePO4 not to be confused with Lithium-Cobalt etc. is in the interest of the boat owners?

Just explain it.

[CharlieJ]

@Jedi

making it impossible to install an isolation transformer to their guidelines

Again, wrong.

using LiFePO4 not to be confused with Lithium-Cobalt etc

What does this even mean?

Never mind. You know, in retrospect, life is too short to joust with you. Go fight with GBN.

[skipperpete]

To stray slightly off topic, here in Queensland it’s not uncommon to see a single wire AC mains supply from the grid with the neutral ( and ground) being made at the household or town. Near where I am now is such a supply and ground that is on the banks of the Russel river and the local fisherman all have stories about bilge pumps starting up and other electrical issues as they cross the bar into the river. Electric shocks seem quite a common event but injuries to swimmers are not a problem..... folks don’t swim much around here due to the unusually high croc population..... and it’s not recorded whether the crocs get shocks

[Jammer]

Originally Posted by skipperpete

To stray slightly off topic, here in Queensland it’s not uncommon to see a single wire AC mains supply from the grid with the neutral ( and ground) being made at the household or town. Near where I am now is such a supply and ground that is on the banks of the Russel river and the local fisherman all have stories about bilge pumps starting up and other electrical issues as they cross the bar into the river. Electric shocks seem quite a common event but injuries to swimmers are not a problem..... folks don’t swim much around here due to the unusually high croc population..... and it’s not recorded whether the crocs get shocks

SWER utility wiring is an abomination. Civilized places like Queensland can afford to put a second wire on the pole.

[goboatingnow]

Originally Posted by CharlieJ

@goboatingnow

That is not the timeline. You could not be more wrong.

The timeline is irelevant ABYC was 20 years behind ISO , in relation to whole boat RCD. Ii took 20 years to arrive at exactly the same place as European boats albeit subjecting the boat owner to absolutely ridiculous pricing ELCIs. I can buy entirely suitable 30 mA RCDBOs for €15-20 yet a ABYC ELCI runs to multiples of that

However you look at ABYC decided to ignore 20 years of good AC practice elsewhere. When it did get around to it many years too late it dreamt up a ELCI ( a term the AC has deprecated for decades ) spec that is OTT , expensive and unnecessarily.

In the meantime NEC codes relating to marina pillars has equally been negligent

[rgleason]

GBN ans svsagres had good suggestions.
https://diysolarforum.com/threads/sm...21#post-615689

ELCI, you don't need a marine specific one. They're realistically just a ground-fault breaker with a 30mA leakage limit (domestic ones for your bathroom etc... have a 5mA limit). The breaker we used was an ASI NDB1L-32C-32-120V which we purchased from Amazon for $45 Canadian. It's UL Listed, is a double pole breaker, and otherwise meets all the AYBC requirements while costing 1/3 the Blue Sea price. We stuck it in a $15 small DIN electrical box, and we added a couple of Blue Sea 120V LED indicators to give us both "power present" indicators and "reverse polarity" indicator. These were just wired to the breaker and ground lug, and we drilled holes in the DIN box to house the LEDs. ...or Amazon ASI NDB1L-32C-32-120V $34!

That's what we've done. When you open the Lazarette, there's a little breaker box on the aft end, within a few inches of our shorepower inlet. The AC goes there, with the ground conductor taking a loop through our Galvanic Isolator, then goes out to the input on our inverter/charger. It's tight, clean, and puts the main disconnect/reconnect right next to the shorepower connector.

Next we need a good galvanic isolator for a reasonable price.