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EBox on the wall + ground cable to engine + Ewof = $1500?


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Hi, I have just bought a yacht which has no AC connection. I have been quoted $1500 for mounting a ready made 10A EBox (they do need to change someting inside the box) on the wall plus installing a ground cable plus doing the Ewof. This sounds to much to me. I doubt the labor is more than 1 hour.

 

Is this realistic? Feels too much.

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How long is a piece of string and is it longer if it's green? But if looking at the surface of the story, it does sound a tad rich. I would be suggesting 2 or 3hrs. It takes longer than you think. Will a extension cable be supplied?

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Hmm in reality it's probably about right.  The old sparks costs are mounting up these days, you would be shocked how much the most basic things cost.  However I do think the work seems a tad rich, more around $ 1000-1200 would be about right I think.  Depends what it includes of course. 

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To issue an ewof, you have to be a licenced electrical inspector.

 

For a quote without a prior inspection, worst case scenario has to be expected - boat full of crap, steel decks and bulkheads, no easy access to the only location it will fit etc etc

etc. An install can take quite a while in this case.

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And, while we are here; I like isolating trannies, because I grew up with them.

Stuff keeps running with them even if there is a minor, err, leak.

But they render RCD's redundant as earth no longer has  polarity.

Then we need to drag you into the 21st century ;-)

 A Galvanic Isolator is the better choice. It is small, cheap, light weight and uses no power unless there is a fault.

You still need the RCD no matter if you have a GI or Isolating Tx even. The Dock RCD protects the distribution up to the box on the boat. Then you will have the Earth isolation part and then you have the boat RCD, which protects everyone on board.

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I know my Solar charge controller supposedly does a 2hr equalisation charge at 9am on the 28th day of each month..

You probably want to change that time to closer to Midday. The EC inputs around 16V and at 9AM especially this time of the year, that could be difficult to get out of the Sun. Errr, I assume we are talking about a Solar Reg doing the EC, not AC power.

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Yea I probably need to check the time on it too.. I don’t remember ever setting a time so could be coming on at night time for all I know

Our solar controller does that. Without re-checking the manual, I thought it keeps on trying to do it until it does it, so starting at 9 am is probably logical, in that it keeps on having a crack until it gets enough ergs from the sun to do it, i.e. it does it on the first big enough piece of sun during the day.

 

That said, I don't really rely on the solar giving a descent equalising charge. If I'm that worried about my batteries, I take them home and do it.

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I’ve just had this done, it was about the same amount as you describe, and similar cost.

I saved a little by running all the cables and conduit, cutting holes etc.

 

 

No galvanic isolator- I wrongly assumed it was mandatory, so didn’t question it..

 

Basically I have I one power point for a dehumidifier and a always on battery charger. Nothing else.

This is on a cat (one without a mast) and sterndrives, so corrosion is a big risk, big deal.

 

Should I be asking him about fitting a galvanic isolator? And how much more in involved?

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Absolutely yes Jason, about $5-600 depending on model. Easy to fit. Break the Ground cable just before it goes to the boat lead socket, put in the Galvanic isolator, it has 2 terminals, one for each end on the wire you just cut.

You can do it yourself. Send me a PM if you want a Galvanic isolator price, or ask your marine sparky.

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Not getting nit picky here, if you don't participation and get the it sorted in your head you don't learn.

An RCD relies on a circuit back to source that causes an imbalance in input /output current.

If you do not tie ground to neutral ie with an isolating transformer, the rcd wont work.

If you do then you wasting your time with the IT.

Not quite. An RCBO works like this;

 

An RCBO measures the current on the live and neutral conductors. If they are not equal it suggests there is current leakage to earth, which could potentially mean someone is touching the live conductor of an appliance– the RCBO will break the ciruit or trip.

 

An RCBO also works as an MCB (Minature or Mains Circuit Breaker). In this operation it is designed to interrupt a current overload in a circuit. RCBOs are rated both by the normal current that are expected to carry, and the maximum short-circuit current that they can safely interrupt. A short circuit is an abnormal low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages, for example if a conducting liquid (water, coffee, tea etc) causes a connection between the live and neutral terminals of a plug or appliance.

 

If you have an Isolating Transformer, there should be an RCBO on the feed side from the dock, BEFORE the Isolating Transformer, and ANOTHER on the output. The Shorepower is a Supply, the Isolating Transformer output is also a supply. ALL supplies (Shorepower, Inverter, Genset etc) should have an RCBO.

 

If you have an Isolating Transformer, you dont need a galvanic isolator, as any fault aboard tries to return to source (the Isolating transformer) and it's impossible to have a leak or short back to the dock.

 

I dont quite agree with Wheels on this, IMO an Isolating Transformer is a step above a galvanic isolator, but everyone certainly should have one or other.

 

Any marine sparky installing or maintaining shorepower should be telling you this if you have neither. If they dont, get another sparky!

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Absolutely yes Jason, about $5-600 depending on model. Easy to fit. Break the Ground cable just before it goes to the boat lead socket, put in the Galvanic isolator, it has 2 terminals, one for each end on the wire you just cut.You can do it yourself. Send me a PM if you want a Galvanic isolator price, or ask your marine sparky.

thanks for that -much appreciated, the amount of knowledge you share here is fantastic.

 

stumped as to why it was not suggested to begin with.

I’ll talk to the sparky, and be in touch about pricing of need be.

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Does the 12v dc neutral bus have to be tied to  Trannies secondary 240V N??  :wtf:

Why is that?

 

Yes. Or said another way which makes it more understandable, the AC system ground (which is the Earth wire) needs to be tied to the Boats DC ground (which is the negative). Thus allowing both to be at the same voltage potential and no possible stray voltage between them.

Note, that the Earth after the Isolator (what ever is used) not before.

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Both Tx and GI do a great job at breaking the Earth between Boat and Shore. There no real disadvantages between either in that part.
The downside of the Tx is purely weight and expense. A 2.4Kva would be in the region of 20 to 30Kg and if you go for a flash Victron unit, the box they are in is large and the price can be as much as it's rating, but depends on the make.
One big plus for Cruisers is that Victron have a unit that automatically senses the input voltage and switches between 110V and 230V keeping the output Voltage the same to suit your on board gear. But it is big money.
the plus with the GI is small and weighs a Kg at most.
If you have a little skill, you can also easily make a GI. All they are are some Diodes and a box that has two terminals for the two earth wires. The Diodes must be a type that short when they fail. There are plenty of diagrams available on line. I do find it hard to understand why they retail for so much when there is about $20 dollars in parts inside a box.

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What confused me was the Last RCBO downstream relies on recreating the boat earth back to the secondary 240V AC N

to work.

An important thing to understand with RCD's/GFI's/RCBO's (all the same) or whatever you want to call them is that they actually have nothing to do with the Earth. They are not connected to the Earth in anyway. Earth Monitoring devices are a completely different beast entirely.

The RCD has only Phase and Neutral entering/exiting the device. Because the current flowing through the device is AC, the current should be equal on both P & N. Should a leakage to earth take place, an imbalance (because the Earth is tied to Neutral) between the P & N is detected. Once that imbalance reaches 30mA, it triggers the circuit and the breaker is disconnected.

The role of the Earth/Ground wire is to take any current back to the supply point, being the switchboard where the N and E are tied together. So should a fault occur (like a current flowing through someone from Phase to Earth) there would be a current on that Earth wire. But in reality, the RCD does not actually detect that Earth wire current.

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Lateral, re read your post, specifically the part I copied/pasted. The RCD does not recreate any earth. That was what I am referring to. They monitor current difference on the conductors, " Nothing to do with the Earth" means they do not have a direct to earthy connection. The Earth wire does not screw into a terminal on the back of the RCD in otherwords. If you read all of my post, I went into that and the why. I am not sure how to make that much clearer.
And no, it makes no difference if the Neutral before the RCD is tied to Earth or not. mThe isolator, being TX or GI lifts the Earth. The Earth is made once again at the Boats switch board, but of course, nothing to do with thew shore powers Earth. Apart from safety issues, there does not even have to be an Earth on the shore power system for the on the boat system to work. Just as long as the Earth and Neutral are tied at the Switchboard. The Earth allows a path for current to flow to a Zero point, being the Neutral/Earth termination. If that zero point is not created, the current differential in the phase/nuetral lines would not be accurate and could be potentially lethal even if the RCD did not trip.

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