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Old 22-01-2012, 12:19   #46
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Re: Best Inverter for the Buck

Your AC ground as posted is probably connected to the DC ground bus. Yes this does invite galvanic corrosion but it is much safer. A galvanic isolator should be installed on any boat with shore power - or an isolation transformer.

I don't think a 3 pole switch is required - I doubt you would ever use (or want to use) the inverter when plugged in to the dock.

2 pole or 3 pole this is the quality of switch you would be better off using rather than the one you posted about. AC crossover switches
Less than $30 for what is almost identical to the switch Blue Seas uses in their rotary source selectors. Blue Seas uses Kraus & Naimer switches which are available at comparable prices.
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Old 22-01-2012, 12:39   #47
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There's no problem leaving the AC protective ground connected to both the shore power and inverter ground. What is the problem which is not addressed by that circuit diagram is that the AC ground and neutral should be connected together at the inverter, because the investor is a power source. Some inverter have a ground relay that does this many do not.

Without neutral and ground connected the AC protective earth circuit will do nothing and will offer no protection one shower power is disconnected. if a AC appliance goes "hot" it will not trip fuses.

Dave
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Old 22-01-2012, 12:50   #48
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Re: Best Inverter for the Buck

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Originally Posted by mitiempo View Post
Your AC ground as posted is probably connected to the DC ground bus. Yes this does invite galvanic corrosion but it is much safer. A galvanic isolator should be installed on any boat with shore power - or an isolation transformer.

I don't think a 3 pole switch is required - I doubt you would ever use (or want to use) the inverter when plugged in to the dock.

2 pole or 3 pole this is the quality of switch you would be better off using rather than the one you posted about. AC crossover switches
Less than $30 for what is almost identical to the switch Blue Seas uses in their rotary source selectors. Blue Seas uses Kraus & Naimer switches which are available at comparable prices.
Thanks. Yes, it seems as if the galvanic isolator would be a wise investment. I'm hoping that a 2 pole switch will be adequate given the isolation provided by a galvanic isolator. If true that would provide a high level of safety and freedom from electrolysis. That AC crossover switch referenced by Maine Sail is a great find. I'll definitely look into that. Now I need to find a similar deal on a galvanic isolator You're right I would not be ordinarily using the inverter while plugged into shore except maybe for testing or in the event that shore power failed and the cord was still connected.
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Old 22-01-2012, 12:53   #49
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Re: Best Inverter for the Buck

Also from ABYC A-31 which covers inverters:
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Old 22-01-2012, 12:58   #50
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Re: Best Inverter for the Buck

The 2 pole switch and the galvanic isolator are two separate issues.

Yes you should have a galvanic isolator. It is there to separate the boat's underwater metal items from the shoreside power to prevent electrolysis - and still allow a fault current to pass along the ground wire to shore when required.

The inverter has nothing to do with galvanic corrosion.

For a galvanic isolator at a good price http://www.yandina.com/GalvInfo.htm
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Old 22-01-2012, 15:17   #51
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Re: Best Inverter for the Buck

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The 2 pole switch and the galvanic isolator are two separate issues.

Yes you should have a galvanic isolator. It is there to separate the boat's underwater metal items from the shoreside power to prevent electrolysis - and still allow a fault current to pass along the ground wire to shore when required.

The inverter has nothing to do with galvanic corrosion.

For a galvanic isolator at a good price Galvanic Isolator Data Sheet
Thanks. Correct me if I'm wrong, but I see them as related as follows. The galvanic isolator isolates the shore ground from ship's ground making it possible to use a 2 (vs 3) pole switch which would otherwise direct connect shore ground to ship's ground when using the inverter. As I understand it there is no reason why shore ground should be direct connected to ship's ground while running the inverter. The 2 pole switch allows this to happen in the absence of a galvanic isolator.

Thanks for the link. The nice thing about that particular galvanic isolator is that it allows for two 30 amp circuits. Turns out I have a second 30 Amp service that services two heat pumps. Normally, we don't have it connected, but this gives us protection on those few occasions.
Pete
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Old 22-01-2012, 16:44   #52
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Re: Best Inverter for the Buck

Unless you are going to use the inverter at the dock, there is not an issue. At the dock when plugged in to shore power there would be no reason to ever run the inverter as far as I can see. And when away from the dock the shore ground doesn't exist.
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Old 22-01-2012, 17:05   #53
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Quote:
Originally Posted by mitiempo
Unless you are going to use the inverter at the dock, there is not an issue. At the dock when plugged in to shore power there would be no reason to ever run the inverter as far as I can see. And when away from the dock the shore ground doesn't exist.
Yes that just leaves the neutral AC earth issue. , simply relay/contactor would sort that.
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Old 22-01-2012, 17:05   #54
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Re: Best Inverter for the Buck

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Originally Posted by mitiempo View Post
Unless you are going to use the inverter at the dock, there is not an issue. At the dock when plugged in to shore power there would be no reason to ever run the inverter as far as I can see. And when away from the dock the shore ground doesn't exist.
Thanks for confirming that. Let me suggest one example. We lose shore power and, therefore, decide to run inverter until it's restored. Naturally, we leave the cord connected while waiting for power to be restored. Turns out the galvanic isolator plays a key role in combination with a rotary selector switch recommended on another forum:
AC cross over switch

The fact that the galvanic isolator you referenced can handle both my 30 Amp services is a nice bonus.
Pete
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Old 22-01-2012, 17:19   #55
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Re: Best Inverter for the Buck

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Yes that just leaves the neutral AC earth issue. , simply relay/contactor would sort that.
The problem, of course, is preventing a situation where neutral is simultaneously tied to ground in two places (eg, on shore and at output of inverter). Isn't that solved by the rotary switch referenced above?
Pete
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Old 22-01-2012, 17:32   #56
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Re: Best Inverter for the Buck

Same switch I recommended in post 46 of this thread and a good value.

It is a 2 pole switch.
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Old 22-01-2012, 17:58   #57
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Re: Best Inverter for the Buck

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Same switch I recommended in post 46 of this thread and a good value.

It is a 2 pole switch.
Thanks and sorry I missed that. Looks like both your galvanic isolator and 2 pole switch recommendations will work well and at very reasonable price. Now I just need to settle on my pure sine wave (standalone) inverter. My favorite (at least on paper) is:
Pure Sine Wave Inverters, Modified Sine Wave Inverters, Battery Chargers, Solar Panels, Solar Charge Controllers

The specs look great although I have read that these are often exaggerated. It does seem that Samlex has a very wide variety of inverters which suggests they are a serious outfit rather than some newcomer. I would love to get some real world experience about this brand.
Pete
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Old 22-01-2012, 18:06   #58
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Re: Best Inverter for the Buck

It is not the wide range of products so much as that it appears that they make the inverters themselves.

The electronics industry is full of companies that sell products sourced offshore with different labels.
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Old 22-01-2012, 18:11   #59
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Quote:
Originally Posted by prroots
The problem, of course, is preventing a situation where neutral is simultaneously tied to ground in two places (eg, on shore and at output of inverter). Isn't that solved by the rotary switch referenced above?
Pete
It could be but I think we're up to 4 poles now,
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Old 22-01-2012, 18:17   #60
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Re: Best Inverter for the Buck

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It is not the wide range of products so much as that it appears that they make the inverters themselves.

The electronics industry is full of companies that sell products sourced offshore with different labels.
Good point. I did call them and they told me that their inverters are made by Cotex. Samlex is the sole North American distributor of Cotex products if I recall correctly.

BTW, my second favorite is the Aims PWRI150012S:
1500 Watt Pure Sine Power Inverter 12 Volt - AimsPower

At least one other poster highly recommends Aims. I prefer the Samlex based upon its higher efficiency, lower standby current, higher surge rating, and double the warranty for starters.
Pete
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