Hull Earth Bond

[Doorman]

I also restrict my postings to subjects that are within my field of expertise, might I suggest you do the same.

At this point I looked at your avatar and smiled.

[ditchcrawler]

 

That is fine, except that it doesn't show the hull bond

It doesn't show the TV or toaster ether.

[Richard10002]

The boat had the AC hull bond in situ when I bought it at 10 years old in 2011. I added a Sterling inverter charger which has a bolt near the connections that go to the battery which is marked with the earth symbol - this I connected to the earth bar in the consumer unit. There are also earth connections where the shore power comes into the inverter, and where the AC power goes from the inverter to the consumer unit.

 

How would I know if I have a neutral-earth bond?

I hope it's OK to bump my question - I'm sure I'm not the only one wondering how you can tell if you have a neutral-earth bond?

[BEngo]

Disconnect all shore power and switch off the inverter. Put a meter on 250+ volt range across the Neutral and Live terminals. This should read zero( that checks there is no power out of the inverter. Next put a meter on the ohms setting between the inverter neutral and the inverter earth. It will read zero if there is an N-E bond.

 

 

ETA I don't know how your inverter is connected. The suggestions above will work where the inverter is on a flying lead. If you have a changeover switch or relay you'll need to go direct to the inverter output.

N

Edited August 12, 2013 by BEngo

[NoFixedAbode]

 

 

As black adder used to say opinion is divided ... you say do it like you showed everyone else says do it as the OP's drawing.

 

So it Seems!

 

I also restrict my postings to subjects that are within my field of expertise, might I suggest you do the same.

 

You might!

[Richard10002]

Disconnect all shore power and switch off the inverter. Put a meter on 250+ volt range across the Neutral and Live terminals. This should read zero( that checks there is no power out of the inverter. Next put a meter on the ohms setting between the inverter neutral and the inverter earth. It will read zero if there is an N-E bond.ETA I don't know how your inverter is connected. The suggestions above will work where the inverter is on a flying lead. If you have a changeover switch or relay you'll need to go direct to the inverter output.N

Sounds straightforward, and logical

 

I've got a Sterling inverter charger, so no changeover switch. I assume it's automatic in the unit.

[nicknorman]

However with the inverter de-powered, the neutral-earth relay (if one is installed ) may also be open, therefore no NE bond therefore no zero resistance connection. Doesn't mean there is no NE bond with the inverter in operation (depending on the inverter).

 

On the subject of GIs, its a 2 terminal device. One terminal to the shore earth, the other terminal to everything else - sockets and hull earth point.

[jonathanA]

However with the inverter de-powered, the neutral-earth relay (if one is installed ) may also be open, therefore no NE bond therefore no zero resistance connection. Doesn't mean there is no NE bond with the inverter in operation (depending on the inverter).

 

On the subject of GIs, its a 2 terminal device. One terminal to the shore earth, the other terminal to everything else - sockets and hull earth point.

nor does it cover the situation where the inverter is centre tapped to earth..

 

I seem to recall gibbo showing how to test E-N bonding with a simple 240v bulb wired to a 13a plug top, but can't find the article....

 

(or maybe I'm suffering from a faulty memory....)

[Doorman]

 

(or maybe I'm suffering from a faulty memory....)

If I were a light bulb I'd be dim! :-)

[mayalld]

It doesn't show the TV or toaster ether.

 

Yes, but as the point under discussion is "where does the GI sit in relation to the hull earth bond"...

[blackrose]

 

Hi, sorry for sticking my nose in where it is probably not wanted but I believe this position is incorrect for the GI, try this:-

 

Shoreline Socket - RCD/MCB - Sockets

|

GI

|

Hull earth bond

Hope this helps,

 

There's no point in having a GI if you install it like this in my opinion.

[clbrof]

Okay I hope this diagram keeps everyone happy. My initial question was just placement and cable thickness. Nothing about GI, but thanks to those who helped.

 

 

Ill be going with this setup unless any can see anything dangerous (I know the wires on the right are bare....)

Edited August 13, 2013 by clbrof

[Happy Go Lucky]

nor does it cover the situation where the inverter is centre tapped to earth..

 

I seem to recall gibbo showing how to test E-N bonding with a simple 240v bulb wired to a 13a plug top, but can't find the article....

 

(or maybe I'm suffering from a faulty memory....)

 

Have a look at post 7 in http://www.canalworld.net/forums/index.php?showtopic=19060&st=0

[by'eck]

Thats so wrong...

Whilst in theory it may be OK, in practice its very easy to have a fault that will bypass the GI and you will never notice until the hull disolves.

 

The GI must sit between shore power earth and boat/hull ground with no possibility of it being bypassed otherwise its useless.

[GUMPY]

 

The GI must sit between shore power earth and boat/hull ground with no possibility of it being bypassed otherwise its useless.

Should have replied to the one I replied to not me we are saying the same thing

[jonathanA]

 

Have a look at post 7 in http://www.canalworld.net/forums/index.php?showtopic=19060&st=0

 

wow - thanks my memory is better than i thought as I must have stumbled across that old post and remembered the content even if i couldn't find it again.

[Richard10002]

Disconnect all shore power and switch off the inverter. Put a meter on 250+ volt range across the Neutral and Live terminals. This should read zero( that checks there is no power out of the inverter. Next put a meter on the ohms setting between the inverter neutral and the inverter earth. It will read zero if there is an N-E bond.ETA I don't know how your inverter is connected. The suggestions above will work where the inverter is on a flying lead. If you have a changeover switch or relay you'll need to go direct to the inverter output.N

OK! I haven't done any of the multimeter tests but it just so happens I bought a cheap plug in tester with lights on the back to tell you a variety of things.

 

Plugged it in to a few mains sockets this morning, when th genny was running via the shore power socket - it goes through the inverter charger, then into a consumer unit with RCD and MCB before supplying the boat 240v supply - the tester showed 2 red lights indicating no earth.

 

Shut down the genny, so nothing via the shore power socket. Left the inverter running,msupplying the boat with 240v and, lo and behold, the tester showed 3 lights, indicating all is well, and there is an earth.

 

So.... It looks like thet is no earth when the genny is running, which kind of suggests there is no route back to the generator negative for the earth. Does this suggest no neutral-earth bond at the genny? How to resolve? Do I connect the earth to neutral in the plug which goes into the genny, or is there some other solution - I probably know enough to be dangerous at the moment, but I'm probably not far from getting it right with a bit of guidance.

[Michael Wooding]

Beware Galvanic Isolators, they are not always doing what you presume they should be. The action of a GI can be completely negated and even reversed (such that it starts to cause corrosion) by simply plugging in a Switched Mode device into the supply. Do I have one if those I hear you ask, most probably you have several, laptop charger, mobile charger, etc., etc.

 

Mike

[Doorman]

Beware Galvanic Isolators, they are not always doing what you presume they should be. The action of a GI can be completely negated and even reversed (such that it starts to cause corrosion) by simply plugging in a Switched Mode device into the supply. Do I have one if those I hear you ask, most probably you have several, laptop charger, mobile charger, etc., etc.

Mike

Gibbo covers this phenomenon on his Smargauge site.

 

Switch mode power supplies create radio frequency interference and that can interfere with TV sets, radios and mobile phones. As CE regulations deem that this interference is not permitted, then it has to be eradicated.

 

To enable this, RFI is directed to ground via a couple of capacitors. "The problem is in order for that to happen, they can cause the galvanic isolator to conduct RFI to ground, so the galvanic isolator is almost permenantly conducting"

 

It is for this reason, that we chose an isolator transformer instead of a galvanic isolator.

Edited August 14, 2013 by Doorman

[ditchcrawler]

Gibbo covers this phenomenon on his Smargauge site.

 

Switch mode power supplies create radio frequency interference and that can interfere with TV sets, radios and mobile phones. As CE regulations deem that this interference is not permitted, then it has to be eradicated.

 

To enable this, RFI is directed to ground via a couple of capacitors. "The problem is in order for that to happen, they can cause the galvanic isolator to conduct RFI to ground, so the galvanic isolator is almost permenantly conducting"

 

It is for this reason, that we chose an isolator transformer instead of a galvanic isolator.

And a lot of people didn't believe him

[jonathanA]

And a lot of people didn't believe him

 

He also goes on to point out that those GI's with status monitors generally have a higher switch on theshold because they have more diodes and can offer better protection against this potential, but by no means certain problem

[Doorman]

And a lot of people didn't believe him

Possibly,

 

But I know who I would prefer to believe when it comes to protecting our hull. I have witnessed many a boat that's equipped with a GI and the hulls have been badly pitted all the same!

[nicknorman]

Possibly,

But I know who I would prefer to believe when it comes to protecting our hull. I have witnessed many a boat that's equipped with a GI and the hulls have been badly pitted all the same!

But... (speaking as someone with a GI!) didn't you have a bit of a pitting issue despite your IT?

[Doorman]

But... (speaking as someone with a GI!) didn't you have a bit of a pitting issue despite your IT?

Yes Nick, we did.

 

And all indications were that it was mill scale (hopefully!). Anything else and I'm sending Mrs Doorman down to Middlewich to get the rapscallion.

 

ETA The boat's coming out next year for its 4 yearly inspection so all will be revealed then.

Edited August 14, 2013 by Doorman

[blackrose]

Beware Galvanic Isolators, they are not always doing what you presume they should be. The action of a GI can be completely negated and even reversed (such that it starts to cause corrosion) by simply plugging in a Switched Mode device into the supply. Do I have one if those I hear you ask, most probably you have several, laptop charger, mobile charger, etc., etc.

 

Mike

 

I tested this a few years ago on my boat with former forum member Chris W. He put a scope acoross my GI while one by one I switched on 2 battery chargers (30 & 40 amp), 2 laptops, various phone chargers, a 240v - 110v step down transformer connected to a stereo system and a few other things.

 

We couldn't force the GI into conduction, but I think my Safeshore GI goes into conduction at 2.4v rather then 1.2v like some other GIs. Also, if you have led status indicators on your GI you will see if a fault condition occurs or the GI is forced in conduction by the RFI of switch-mode appliances

Possibly,

 

But I know who I would prefer to believe when it comes to protecting our hull. I have witnessed many a boat that's equipped with a GI and the hulls have been badly pitted all the same!

 

Pitting isn't always the result of galvanic action.

 

Edit: as I see you discovered yourself.

Edited August 14, 2013 by blackrose