Battery VE not bonded to hull

[arreff]

Hello all,

 

Should I be concerned that my narrowboat batteries are not explicitly bonded to the hull?

 

They are bonded to the engine, which in turn has continuity with the hull via the engine mounts though. 

 

Also, where should I bond my ac / inverter casing to? 

 

Many thanks 

[OldGoat]

2 minutes ago, arreff said:

Hello all,

 

Should I be concerned that my narrowboat batteries are not explicitly bonded to the hull?

 

They are bonded to the engine, which in turn has continuity with the hull via the engine mounts though. 

 

Also, where should I bond my ac / inverter casing to? 

 

Many thanks 

Not necesarily bonded via the engine mounts as the mounts usually / often have a shock absorbing compound  which will / might electrocally insulate the engine from the hull.

 

That's wh current practice and 'regulations'  suggest / require a separate earthing point on the hull to which all the other earths are joined. It's this point to which you should  connect your inverter earth to.

 

If that's done properly - then you need to worry less......

[Tony Brooks]

10 minutes ago, arreff said:

Hello all,

 

Should I be concerned that my narrowboat batteries are not explicitly bonded to the hull?

 

They are bonded to the engine, which in turn has continuity with the hull via the engine mounts though. 

 

Also, where should I bond my ac / inverter casing to? 

 

Many thanks 

 

If the engine is flexibly mounted then if you don't want the risk of melted/burned control cables add another 25mm min CCSA cable from the  engine negative point to say a bolt or screw through the engine bed.

 

The AC earth bond is ideally placed close to the DC bond for easy identification but on a separate fixing so that in the unlikely event of a common (DC & AC) fixing becoming detached together with an AC fault you don't put 240V onto the 12V circuits.

[arreff]

Thank you both for your responses

 

So considering I have my bss coming up and currently have neither in place, I will:

- Add two earthing points, probably on the engine bearers.

- attach one to the engine 'earthing point'

- attach the other to the earthing point on the inverter, which is common with the earths in the sockets

 

Should I also be running a cable from the consumer unit earth bus bar? Or is it enough to just use the one provided on the inverter?

 

Thanks again for the speedy and helpful responses 

 

[Tony Brooks]

9 minutes ago, arreff said:

Thank you both for your responses

 

So considering I have my bss coming up and currently have neither in place, I will:

- Add two earthing points, probably on the engine bearers.

- attach one to the engine 'earthing point'

- attach the other to the earthing point on the inverter, which is common with the earths in the sockets

 

Should I also be running a cable from the consumer unit earth bus bar? Or is it enough to just use the one provided on the inverter?

 

Thanks again for the speedy and helpful responses 

 

Not sure what you mean by that, 12V or 240V consume unit? I assume 240V.

As  long as the earth circuit is continuous from inverter/shore power socket to every other outlet then use the one on the inverter but make sure the cable is large enough. As i am not well up on 240V circuits I am not sure what it shoudl be so others will put me right but I suspect 7 sq mm CCSA

[BEngo]

Stick to one earth.  I would use the inverter earth and check that the inverter earth is actually connected to the consumer unit.

 

Ideally the DC negative bond and the 240V earth bond are connected to the same point.  It is also a good idea to label the connection "Safety Electrical Earth  Do Not Remove."  You can do this easily and cheaply by buying a pipe earthing clamp from a DIY shed.  They come with a suitable metal label.

N

Edited August 13, 2020 by BEngo

[arreff]

6 minutes ago, Tony Brooks said:

Not sure what you mean by that, 12V or 240V consume unit? I assume 240V.

As  long as the earth circuit is continuous from inverter/shore power socket to every other outlet then use the one on the inverter but make sure the cable is large enough. As i am not well up on 240V circuits I am not sure what it shoudl be so others will put me right but I suspect 7 sq mm CCSA

Thanks tony, yes I meant the 240v consumer unit. 

5 minutes ago, BEngo said:

Stick to one earth.  I would use the inverter earth and check that the inverter earth is actually connected to the consumer unit.

 

Ideally the DC negative bond and the 240V earth bond are connected to the same point.  It is also a good idea to label the connection "Safety Electrical Earth  Do Not Remove."  You can do this easily and cheaply by buying a pipe earthing clamp from a DIY shed.  They come with a suitable metal label.

N

Thanks for this, I'll take the earths to the same spot and label them. Good tip on the label!

 

 

Cheers all. 

[Murflynn]

13 minutes ago, BEngo said:

Stick to one earth.  I would use the inverter earth and check that the inverter earth is actually connected to the consumer unit.

 

Ideally the DC negative bond and the 240V earth bond are connected to the same point.  It is also a good idea to label the connection "Safety Electrical Earth  Do Not Remove."  You can do this easily and cheaply by buying a pipe earthing clamp from a DIY shed.  They come with a suitable metal label.

N

I read somewhere that the DC and AC earth points on a steel boat should be separate but adjacent, and clearly marked.  I seem to remember that this is because if the earths are on the same stud, there is a risk of the cables being removed without being separated from each other - I can't recall what the hazard would be in that case.   

 

EDIT:   I see that Tony has already pointed this out - he knows, you should follow his advice.

Edited August 13, 2020 by Murflynn

[WotEver]

2 hours ago, BEngo said:

Ideally the DC negative bond and the 240V earth bond are connected to the same point. 

Sorry, but no they shouldn't, for the reasons that Tony B has already explained. Two studs, welded to the engine bearers or other convenient bit of hull, adjacent to each other, is ideal.

2 hours ago, arreff said:

Should I also be running a cable from the consumer unit earth bus bar? Or is it enough to just use the one provided on the inverter?

For simplicity of understanding the system for future owners (or anyone else who might have cause to work on the boat), I always advocate running the earth bonding cable from the consumer unit, just as you would in a building.  The inverter bonding point can be ignored.  However, there's nothing wrong electrically with doing it the way you describe.  Use at least 4mm² cable for the 230V earth bond, and at least 25mm² for the DC negative bond.

[GUMPY]

My bonding point is on one bolt and I believe perfectly safe.

Read below before criticising;

The engine bed is tapped, and all paint removed in that area above and below, the DC-ve is on the underside of the bed with the bolt tightened up. The AC ground is on the topside of the bed with a nut above it. Can anyone explain why this is may not be safe?

 

Edited August 13, 2020 by Loddon

[Tony Brooks]

Sounds fine to me but that is not what most boaters would understand by both bonds being on the same stud.

 

Actually I think it may be better the other way round because the 12V bond may need removing during engine work so it could be while the AC bond would still be in place.

Edited August 13, 2020 by Tony Brooks

[GUMPY]

2 minutes ago, Tony Brooks said:

Sounds fine to me but that is not what most boaters would understand by both bonds being on the same stud.

 

Actually I think it may be better the other way round because the 12V bond may need removing during engine work so it could be while the AC bond would still be in place.

To be honest I cant remember which way round it is and the boat is 250miles away so I couldn't look, I just picked one way at random.

 

 

[RAP]

It would be great to see some examples of how it should be done. Are any pics available? The search facility and Google don’t appear helpful.

 

Thanks.

[GUMPY]

Another musing:

I wonder how many boats there are with welded studs where the ring crimp is held off the engine bed by the weld, thus not making full contact.

[WotEver]

1 hour ago, Loddon said:

The engine bed is tapped, and all paint removed in that area above and below, the DC-ve is on the underside of the bed with the bolt tightened up. The AC ground is on the topside of the bed with a nut above it.

Sounds like a good solution