isolating transformer

[BruceinSanity]

1 hour ago, WotEver said:

But it would do no real harm if left in place. 

We've left ours in place and rely on it if using a shoreline for just a few days. But when mooring for longer, as in the winter, the Airlink is dug out from under the bed and deployed.

[WotEver]

59 minutes ago, BruceinSanity said:

We've left ours in place and rely on it if using a shoreline for just a few days. But when mooring for longer, as in the winter, the Airlink is dug out from under the bed and deployed.

Sounds like a plan

[Sea Dog]

3 hours ago, WotEver said:

As Robbo stated, it's not just the earth that's broken, so is live and so is neutral. The boat has no reference to the shore/earth at all.

But it would do no real harm if left in place. 

So the earth from the shore supply side is wired to the iron core in the IT whilst the earth on the boat side is connected to neutral of the secondary inside the IT itself, right?

I can see that the GI in that earth line will do no harm whilst the IT is in circuit and be a good thing if the IT is taken out for quick short period connection to shore supply as suggested earlier.  When the IT is connected, how does the E-N bond in the IT fit with the boat's existing AC earth bonding to the hull or with what's going on in clever inverter/chargers? There's still a single hull bonding point, but are there any implications to duplicating the boat side E-N bond?

[WotEver]

2 minutes ago, Sea Dog said:

So the earth from the shore supply side is wired to the iron core in the IT whilst the earth on the boat side is connected to neutral of the secondary inside the IT itself, right?

Spot on. 

3 minutes ago, Sea Dog said:

I can see that the GI in that earth line will do no harm whilst the IT is in circuit and be a good thing if the IT is taken out for quick short period connection to shore supply as suggested earlier.

Absolutely, yes. 

3 minutes ago, Sea Dog said:

When the IT is connected, how does the E-N bond in the IT fit with the boat's existing AC earth bonding to the hull or with what's going on in clever inverter/chargers? There's still a single hull bonding point, but are there any implications to duplicating the boat side E-N bond?

It's electrically exactly the same as if the IT didn't exist.

Shore power earth is bonded to Neutral either at the substation or as it enters the premises, depending on the distribution system, so all you are doing with the N-E bond on an IT, or a generator, or an inverter is replicating an 'ordinary' mains supply. 

If you really want to boggle yourself with what 'earth' is as supplied by the electricity supplier have a read of this: http://electrical.theiet.org/wiring-matters/16/earthing-questions.cfm?type=pdf

[Sea Dog]

12 minutes ago, WotEver said:

It's electrically exactly the same as if the IT didn't exist.

Thanks for that WotEver. I've got a fairly decent grasp of things electrical, and I'm happy with what the grid does with earth connections. I believe there's something in the BSS about a single AC/DC bonding point, so I just thought I'd ask someone who might know off the top of his headnabout that duplication of the E-N bond on the boat side of the IT rather than try to get my own head around it at this time of night!

With an E-N bond already existing in the boat then, the additional E-N bond on the secondary side inside the IT is not strictly necessary but there are no implications of that duplication. Correct?

[WotEver]

3 minutes ago, Sea Dog said:

With an E-N bond already existing in the boat then...

There shouldn't be one. 

The AC earth is bonded to the hull, all sources should be N-E bonded at source, the boat shouldn't have an N-E bond itself. 

[WotEver]

I see what you meant now when you wrote

34 minutes ago, Sea Dog said:

are there any implications to duplicating the boat side E-N bond?

There's no such thing (or shouldn't be) as 'the boat side E-N bond'. 

[Sea Dog]

5 minutes ago, WotEver said:

There's no such thing (or shouldn't be) as 'the boat side E-N bond'. 

Ah, I see I'm labouring under a misapprehension, brought about, I think, by recalling my Mastervolt Combo's ability to make/break that connection automatically if selected in its settings!  So, we'd be introducing a boat side E-N bond as a result of adding the IT, thus replacing the connection to the shoreside earth which the IT has isolated.

[WotEver]

2 minutes ago, Sea Dog said:

So, we'd be introducing a boat side E-N bond as a result of adding the IT, thus replacing the connection to the shoreside earth which the IT has isolated.

Yup. It's making its own little private boat side power station if you like  

What your Mastervolt was doing was creating the Inverter N-E bond as already discussed

Tony

[Sea Dog]

2 minutes ago, WotEver said:

Yup. It's making its own little private boat side power station if you like  

What your Mastervolt was doing was creating the Inverter N-E bond as already discussed

Tony

Excellent, thanks Tony. I was just going to edit that last sentence of mine as I thought I'd not phrased it well, but you cleverly interpreted what I was driving at!