Earthing

[FadeToScarlet]

 

I don't really do 240v yet, but this looks like a bad idea (on someone else's boat).

[WotEver]

DSC_1287.JPG

 

I don't really do 240v yet, but this looks like a bad idea (on someone else's boat).

That's what happens when you allow a non boat sparks onto a boat.

[Geo]

DSC_1287.JPG

 

I don't really do 240v yet, but this looks like a bad idea (on someone else's boat).

 

No not a bad idea, it is technically correct where using copper pipe. The copper pipe conducts electricity and it is important to make sure it is earthed so that if a mains cable or something connects to it the the trip will operate and stop the possibility of someone getting a shock.

That's what happens when you allow a non boat sparks onto a boat.

 

Oh

[Guest]

Hard to say from the photo, but it may just be equipotential cross bonding of metal pipework.

[FadeToScarlet]

 

No not a bad idea, it is technically correct where using copper pipe. The copper pipe conducts electricity and it is important to make sure it is earthed so that if a mains cable or something connects to it the the trip will operate and stop the possibility of someone getting a shock.

I'll need to trace the other end of the cable, but it looks like it goes to the consumer unit and not an earth point on the hull.

[Geo]

I'll need to trace the other end of the cable, but it looks like it goes to the consumer unit and not an earth point on the hull.

 

I believe it should go to the consumer unit. The only AC earth to the hull should be from the consumer unit.

[Chewbacka]

Depends as to what the other end of the wire is connected to and in how many different places the pipe work is connected to the hull.

[Guest]

Depends as to what the other end of the wire is connected to and in how many different places the pipe work is connected to the hull.

That is how I see it. Without knowing the full system it is hard to comment.

[alan_fincher]

On the available information, this bit looks OK to me, and is probably more correct than boats that have 240 volts, but don't bother with bonding any metal pipework to earth.

 

I also think the earth wire(s) will ideally trace back to the 240v consumer box, but I don't think they ncessarily need to run all the way there. Connecting to earth at any point on the boats 240v wiring would be OK, I think, (but happy to be corrected if there is a good reason why not).

[Guest]

I have only two short pieces of copper pipe on our boat, the purpose of which is to heat the calorifier from the engine. As there is a 240V element in the calorifier, I chose to cross bond the two copper pipes. Some other boats I have seen have a similar arrangement, some don't.

[Geo]

Depends as to what the other end of the wire is connected to and in how many different places the pipe work is connected to the hull.

 

Of course the copper pipe work should not be connected to the hull anywhere otherwise other things come into play. It is likely that the copper pipe was installed after the lining and therefore should not be in contact with the hull.

 

I have seen boats with CU piping not bonded and bonded. To me it should be bonded to the main earth and should not touch the main hull anywhere.

[Geo]

On the available information, this bit looks OK to me, and is probably more correct than boats that have 240 volts, but don't bother with bonding any metal pipework to earth.

 

I also think the earth wire(s) will ideally trace back to the 240v consumer box, but I don't think they ncessarily need to run all the way there. Connecting to earth at any point on the boats 240v wiring would be OK, I think, (but happy to be corrected if there is a good reason why not).

 

I see no problem if the earth is picked up from one of the existing AC earths. Spec wise I think there is a requirement for it to be a certain size, can't remember off the top of my head, but linking to a 2.5mm² earth run I would have thought OK.

[WotEver]

Depends as to what the other end of the wire is connected to and in how many different places the pipe work is connected to the hull.

 

Quite.

Equipotential bonding should be in 4mm² but if the result is more than one connection to the hull then it's quite obviously bad practice.

[nicknorman]

Of course most boats use plastic plumbing and so the pipes don't need earthing! On our boat it is plastic plumbing except for the upstages to the radiators that are short lengths of copper coming up from the floor (just for the looks). These are not bonded and I see no need since there is no hidden mains wiring in the vicinity and anything that is a hazard above floor level (trailing appliance cable etc) is already a hazard and not substantially worsened by possibly touching a pipe. And of course ultimately, an RCD should protect life.

 

If there is predominately copper plumbing then I think it does make sense to Earth it. As has been said, one would want to be sure that this didn't create another Earth path to the hull but I think in general piping isn't connected to the hull and of course if it is, another Earth connection isn't going to enhance safety. A simple meter check to see if the piping is zero resistance to hull or not, would indicate whether it was a good idea to add an Earth bond or not.

Edited December 11, 2016 by nicknorman

[Murflynn]

Nick, why is it good practice to bond copper piping in a house to the earth wire, and not for a boat?

or is that not what you meant?

[nicknorman]

Nick, why is it good practice to bond copper piping in a house to the earth wire, and not for a boat?

or is that not what you meant?

Oops, I made a typo. Should be "does" not "doesn't". Thanks for the heads up. Now edited

[Chewbacka]

I have only two short pieces of copper pipe on our boat, the purpose of which is to heat the calorifier from the engine. As there is a 240V element in the calorifier, I chose to cross bond the two copper pipes. Some other boats I have seen have a similar arrangement, some don't.

Probably on the boats that don't cross bond the short bits of pipe into the calorifier, the calorifier is copper with an immersion heater, so the immersion, calorifier and pipes are all bonded together via the copper calorifier and earthed via the immersion heater earth.

[Guest]

Of course most boats use plastic plumbing and so the pipes don't need earthing! On our boat it is plastic plumbing except for the upstages to the radiators that are short lengths of copper coming up from the floor (just for the looks). These are not bonded and I see no need since there is no hidden mains wiring in the vicinity and anything that is a hazard above floor level (trailing appliance cable etc) is already a hazard and not substantially worsened by possibly touching a pipe. And of course ultimately, an RCD should protect life.

 

If there is predominately copper plumbing then I think it does make sense to Earth it. As has been said, one would want to be sure that this didn't create another Earth path to the hull but I think in general piping isn't connected to the hull and of course if it is, another Earth connection isn't going to enhance safety. A simple meter check to see if the piping is zero resistance to hull or not, would indicate whether it was a good idea to add an Earth bond or not.

Seems reasonable to me.

Probably on the boats that don't cross bond the short bits of pipe into the calorifier, the calorifier is copper with an immersion heater, so the immersion, calorifier and pipes are all bonded together via the copper calorifier and earthed via the immersion heater earth.

I think this is perfectly true, and I just cross bonded because it seemed a good idea at the time. At worst, I don't see it will do any harm.

[Chewbacka]

Seems reasonable to me.

I think this is perfectly true, and I just cross bonded because it seemed a good idea at the time. At worst, I don't see it will do any harm.

Agreed, does no harm at all.

[BWM]

What would be best practice for a gravity heating system fed by a back boiler/solid fuel stove? Reading this thread made me wonder, as the flue would almost certainly make contact with the cabin top (hull).

[RD1]

In a house, equipotential bonding is essential for example, two seperate taps on a wash hand basin, and on a bath, should the hot suddenly become live, for example, a faulty immersion heater with a poor earth, then the hot tap, could be hot in more ways than one, now if the cold is earthed, via the copper piping or earth bonds then grabbing both taps could electrocute someone, straight across the heart, wet hands etc etc... game over.

 

Now, anyone can buy these plastic leak fix push on fittings, BUT, they have probably compromised the earth to any device down line, as the copper to copper pipe has now been insulated.

 

Don't underestimate the importance of earthing and bonding, if in doubt, contact a qualified person, unfortunately not all electricians understand marine wiring. Don't be misled by a Boat Safety Certificate, it does not check any of the mains wiring, they only look at plugs and sockets, to ensure that under no circumstances an accessible pin on a plug is live. They cannot test RCD's either, so if you have one, it might be faulty and not trip at the right current, or within the required time, or not trip at all.

 

Then we have galvanic isolators, when they work they are fine, but if an earth fault occurs that trips an rcd or trips a breaker, or blows a fuse, then the galvanic isolator should be tested, easy enough, but if not done, then the unit might have gone open circuit, and you could loose your safety earth on the boat, which could affect how your rcd might trip.

 

Richard

[nicknorman]

In a house, equipotential bonding is essential for example, two seperate taps on a wash hand basin, and on a bath, should the hot suddenly become live, for example, a faulty immersion heater with a poor earth, then the hot tap, could be hot in more ways than one, now if the cold is earthed, via the copper piping or earth bonds then grabbing both taps could electrocute someone, straight across the heart, wet hands etc etc... game over.

 

Now, anyone can buy these plastic leak fix push on fittings, BUT, they have probably compromised the earth to any device down line, as the copper to copper pipe has now been insulated.

 

Don't underestimate the importance of earthing and bonding, if in doubt, contact a qualified person, unfortunately not all electricians understand marine wiring. Don't be misled by a Boat Safety Certificate, it does not check any of the mains wiring, they only look at plugs and sockets, to ensure that under no circumstances an accessible pin on a plug is live. They cannot test RCD's either, so if you have one, it might be faulty and not trip at the right current, or within the required time, or not trip at all.

 

Then we have galvanic isolators, when they work they are fine, but if an earth fault occurs that trips an rcd or trips a breaker, or blows a fuse, then the galvanic isolator should be tested, easy enough, but if not done, then the unit might have gone open circuit, and you could loose your safety earth on the boat, which could affect how your rcd might trip.

 

Richard

 

I certainly agree with you if the system is predominately copper as in old houses. But surely in new houses it is predominantly plastic? I recently had this conundrum when I redid our house bathroom from scratch. Although I used mainly plastic piping there were a few bits of copper eg into the back of the shower mixer (for space reasons) and I wasn't sure whether these should be earthed or not. However I decided not, since there was no wiring anywhere near and thus no possibility of that foot or so of copper going live. The rest of the house's plumbing is copper and is earthed. Well rather, it is properly earthed now, the previous "electrician" had just twisted an earth wire around a pipe under the floorboards that might or might not have actually made a good contact onto the old and tarnished copper! I replaced that with a proper clamp/tag. I also fitted an RCD to the bathroom circuit which was not otherwise present in our Victorian house at all. So I'm not sure whether I fully complied with the regs, but one thing is for sure it is a lot safer now than it was!

[Geo]

Then we have galvanic isolators, when they work they are fine, but if an earth fault occurs that trips an rcd or trips a breaker, or blows a fuse, then the galvanic isolator should be tested, easy enough, but if not done, then the unit might have gone open circuit, and you could loose your safety earth on the boat, which could affect how your rcd might trip.

 

Richard

 

I take it you meant to reference this to when on shoreline?

 

I certainly agree with you if the system is predominately copper as in old houses. But surely in new houses it is predominantly plastic? I recently had this conundrum when I redid our house bathroom from scratch. Although I used mainly plastic piping there were a few bits of copper eg into the back of the shower mixer (for space reasons) and I wasn't sure whether these should be earthed or not. However I decided not, since there was no wiring anywhere near and thus no possibility of that foot or so of copper going live. The rest of the house's plumbing is copper and is earthed. Well rather, it is properly earthed now, the previous "electrician" had just twisted an earth wire around a pipe under the floorboards that might or might not have actually made a good contact onto the old and tarnished copper! I replaced that with a proper clamp/tag. I also fitted an RCD to the bathroom circuit which was not otherwise present in our Victorian house at all. So I'm not sure whether I fully complied with the regs, but one thing is for sure it is a lot safer now than it was!

 

In England & Wales you would not have been permitted to change the bathroom wiring or alter the consumer unit. I think it is Part P of the building regs that apply down here and I assume they do not apply up there.

Edited December 11, 2016 by Geo

[FadeToScarlet]

The worry I have is that there might not be another earth point- that the 240v earth is only connected to the pipes, which aren't themselves connected to the hull.

[Guest]

The worry I have is that there might not be another earth point- that the 240v earth is only connected to the pipes, which aren't themselves connected to the hull.

That would need checking.

 

I certainly agree with you if the system is predominately copper as in old houses. But surely in new houses it is predominantly plastic? I recently had this conundrum when I redid our house bathroom from scratch. Although I used mainly plastic piping there were a few bits of copper eg into the back of the shower mixer (for space reasons) and I wasn't sure whether these should be earthed or not. However I decided not, since there was no wiring anywhere near and thus no possibility of that foot or so of copper going live. The rest of the house's plumbing is copper and is earthed. Well rather, it is properly earthed now, the previous "electrician" had just twisted an earth wire around a pipe under the floorboards that might or might not have actually made a good contact onto the old and tarnished copper! I replaced that with a proper clamp/tag. I also fitted an RCD to the bathroom circuit which was not otherwise present in our Victorian house at all. So I'm not sure whether I fully complied with the regs, but one thing is for sure it is a lot safer now than it was!

Hope you are part P registered?

Edited December 11, 2016 by Guest