Generator Earthing

[BD3Bill]

I have bought a 1.6kva suitcase generator so I can do work on our boat ( no hook up at mooring ).

 

Should I use an earth spike on the genny when using power tools on an extension lead ?

 

I am using a plug in RCD between tool & extension socket.

 

And

 

I do plan to use the genny to run a 1 or 1.5kw immersion in the future.

 

The boat has an RCD box but no earth bond to the hull that I can see.

Hence why I haven't connected the genny to the boats mains inlet !!! and have disconnected the existing 240 circuits just to be sure.

 

Do I need to bond to the hull if I use an earth spike on the genny?

 

Where should the hull bond go from…. the RCD box?

 

Plenty of good places on the engine beds for tother end.

 

Cheers

Bill

 

 

 

 

 

 

[BEngo]

An earth spike and an RCD plug are a good idea when using power tools on an extension lead.

 

When using the genny as a shore line the generator earth point ( which should also be bonded to the generator neutral) should be bonded to the hull, (assuming it's not some strange invertor type generator, in which case see the Smartgauge site for an analysis of the various inverter output types and what to do). The hull end can be anywhere though it is good practice to have it next to but separate from the DC negative hull bond.

 

The earth spike is not then essential as the boat hull does that, though it is still a good idea. Do not rely on an earth spike instead of a generator earth/neutral bond to the hull.

 

N

[Justme]

Its not going to run a 1.5kw heater.

[BD3Bill]

Rated 1.6kw and Peak 2kw, I think it will surely?

[BD3Bill]

An earth spike and an RCD plug are a good idea when using power tools on an extension lead.

 

When using the genny as a shore line the generator earth point ( which should also be bonded to the generator neutral) should be bonded to the hull, (assuming it's not some strange invertor type generator, in which case see the Smartgauge site for an analysis of the various inverter output types and what to do). The hull end can be anywhere though it is good practice to have it next to but separate from the DC negative hull bond.

 

The earth spike is not then essential as the boat hull does that, though it is still a good idea. Do not rely on an earth spike instead of a generator earth/neutral bond to the hull.

 

N

 

 

Thanks so much for this, just plain and simple. I had looked long and hard at previous threads and just become confuddled. Fairplay!

 

Cheers Bill

[Justme]

Rated 1.6kw and Peak 2kw, I think it will surely?

 

 

Dont confuse kVa with kW.

 

 

Ok on a heater they are much closer than with other types of device.

[Arthur Brown]

A RCD works by detecting current in one AC live that's NOT in the other AC Live Unless there is a way for that current to go somewhere else than the RCD has nothing to detect and can't work. -So an earth at the generator end (making one core earth referenced) is a good plan. BUT the better plans include being particularly careful with the "In service user inspections" HSE are now saying that 90+% of all appliance failures can be SEEN by a competent USER and equipment should be taken out of service for repair (etc) at this stage not a year+ later at PAT test time.

[smileypete]

Worth having a socket tester, it will show if there's no neutral to earth bond, for further investigation:

 

http://www.ebay.co.uk/itm/NEW-UK-Mains-Test-Power-Plug-In-Trailing-Socket-Tester-Wiring-Safety-Check-13A-/220859602281?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET

 

As mentioned, pressing the RCD test button only checks the integrity of the RCD itself. It does NOT verify a functioning neutral to earth bond which is needed for the RCD to trip in the event of a fault.

 

cheers, Pete.

~smpt~

Edited May 24, 2014 by smileypete

[BD3Bill]

Worth having a socket tester, it will show if there's no neutral to earth bond, for further investigation:

 

http://www.ebay.co.uk/itm/NEW-UK-Mains-Test-Power-Plug-In-Trailing-Socket-Tester-Wiring-Safety-Check-13A-/220859602281?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET

 

As mentioned, pressing the RCD test button only checks the integrity of the RCD itself. It does NOT verify a functioning neutral to earth bond which is needed for the RCD to trip in the event of a fault.

 

cheers, Pete.

~smpt~

 

Hi Pete. Thanks as always, shall get one.

 

Re reading the instruction manual for the genny however ( Briggs & Stratton P2000 with a 12v output as well, so inverter type ) it does actually state in there the neutral is floating.

It's under warranty so I shan't be pulling it apart & fiddling with it.

 

So how the earthing point provided works is beyond me ! Federal law in some countries require it, they go no further in explanation.

 

Interestingly when I turn the genny off with the extension & a tool (stopped) still plugged in the RCD plug does trip, but I guess this is just the current changing as the field in the genny's windings collapses?

 

Cheers Bill

[Ex- Member]

Worth having a socket tester, it will show if there's no neutral to earth bond, for further investigation:

 

http://www.ebay.co.uk/itm/NEW-UK-Mains-Test-Power-Plug-In-Trailing-Socket-Tester-Wiring-Safety-Check-13A-/220859602281?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET

 

As mentioned, pressing the RCD test button only checks the integrity of the RCD itself. It does NOT verify a functioning neutral to earth bond which is needed for the RCD to trip in the event of a fault.

 

cheers, Pete.

~smpt~

 

 

Hi Pete

 

Out of interest we have this model we bought a good 9 years ago now. I've used it every time i've done anything to the 240v system, but unsure weather it checks earth like the one you posted.

 

http://cpc.farnell.com/1/1/39364-socket-tester-fault-locator-sok32-socket-see.html

Edited May 26, 2014 by Julynian

[blackrose]

 

Hi Pete. Thanks as always, shall get one.

 

Re reading the instruction manual for the genny however ( Briggs & Stratton P2000 with a 12v output as well, so inverter type ) it does actually state in there the neutral is floating.

It's under warranty so I shan't be pulling it apart & fiddling with it.

 

So how the earthing point provided works is beyond me ! Federal law in some countries require it, they go no further in explanation.

 

Interestingly when I turn the genny off with the extension & a tool (stopped) still plugged in the RCD plug does trip, but I guess this is just the current changing as the field in the genny's windings collapses?

 

Cheers Bill

 

Ah, I'm glad we've identified that. I know that most suitcase generators have a floating earth, but it's not wise to assume this when giving advice.

 

The earthing point on your generator is for the earthing the generator chassis.

 

For the RCD on your consumer unit to work the generator or the cable should also be N-E bonded. If you do the latter the cable should be labelled as such and not used for any other purpose than connecting the generator to the boat. If on the other hand you're just using the generator to run power tools and you don't want it to go through the boat then it's best to leave the generator's floating earth as it is, but then if you do connect the floating earth generator to your boat don't expect the RCD to work.

 

The other thing is that high voltages at start-up and shut down of some generators can damage sensitive electrical equipment. I know a bloke who set fire to his expensive combi inverter this way. It shouldn't have happened but it did. I always try to remember to start the generator and then plug the power cable (which is already connected to the boat) into the generator. Then I switch the AC selector switch from Off to Generator. I do the opposite (with dry hands) when I switch the generator off. I don't have a combi and my AC input goes straight to the consumer unit, so perhaps what I'm doing is unnecessary - I just want to protect any connected equipment on my mains ring from high voltages at start-up and shut down. Perhaps someone more knowledgeable can advise?

Edited May 26, 2014 by blackrose

[Arthur Brown]

while the B&S P2000 is an inverter generator, the assumption above that "has also a 12v output" certainly ISN'T an indicator of an inverter generator -I have two big rotating machine alternators that both have "12v" outputs on them -why I don't know as those are NBG for charging due to the low rate and poor voltage control.

[BD3Bill]

Well now, we will all be glad to hear that I have looked at the Smart Gauge site and found a suitable wiring diagram for my use.

 

Thanks again Guys!

[smileypete]

Hi Pete

 

Out of interest we have this model we bought a good 9 years ago now. I've used it every time i've done anything to the 240v system, but unsure weather it checks earth like the one you posted.

 

http://cpc.farnell.com/1/1/39364-socket-tester-fault-locator-sok32-socket-see.html

 

That checks the earth too, that's a good 'un.

 

Interestingly when I turn the genny off with the extension & a tool (stopped) still plugged in the RCD plug does trip, but I guess this is just the current changing as the field in the genny's windings collapses?

 

All the plug in and inline ones do that, if they didn't there's a risk Joe Bloggs public might misinterpret a power cut as an RCD trip and be fiddling with the mower blade when the power comes back on.

 

Anyway if you're just using one or two double insulated (plastic bodied) tools from the genny then running it isolated without RCD capability is fine for short term use.

 

But for running more stuff and particularly through the shoreline socket, it's usually recommended to have neutral to earth bonding in the genny or via a special lead, plus RCD, plus hull earth bond.

 

If you're not confident and absolutely sure of how to make such a lead a good registered sparks should be able to do it for £not much. The lead should be indelibly lablelled something like, 'ONLY use with XXX genny AND RCD protection.'

 

Using the socket tester while the genny is running will give some assurance the earth isn't floating and the neutral-earth bond is OK.

 

Couple of links:

 

http://www.justgenerators.co.uk/pages/FAQ.htm

http://www.hse.gov.uk/foi/internalops/ocs/400-499/oc482_2.htm (bit technical)

 

cheers, Pete.

~smpt~

Edited May 26, 2014 by smileypete

[Ex- Member]

 

That checks the earth too, that's a good 'un.

 

Cheers Pete, a good electrician told me to buy that model when we first started fitting out, so I did. So every time I did anything to the 240v system I would plug it in afterwards to check my handy work wasn't going to electrocute anyone

 

They are really good though especially for the DIYer doing their own 240v

[BD3Bill]

Would anyone agree with the practice of using a plug with a link wire from earth to neutral, in the spare socket, on a generator with two outlets ?

 

This apparently creates the necessary neutral/earth bond needed for a circuit breaker to work on an inverter genny with a floating neutral……. without ripping it to bits and permanently converting it.

 

Oh yes, I have done a lot of reading in the last 4 days folks :0)

 

Haven't found how to wire up a 'magic' hook-up lead though! :0(

 

Cheers Bill

 

( Realise that hulbond/RCD panel still needed)

Edited May 27, 2014 by BD3Bill

[smileypete]

Would anyone agree with the practice of using a plug with a link wire from earth to neutral, in the spare socket, on a generator with two outlets ?

 

Sounds like it's asking to be forgotten, and you're already almost halfway to a earth-neutral bonding lead anyway.

 

Haven't found how to wire up a 'magic' hook-up lead though! :0(

 

It's just a short 16a plug to 16a trailing socket lead with appropriate indelible labelling, and the earth linked to neutral at one end (or both ends for extra reliability, why not...)

 

Probably a good competent reputable experienced boatyard bloke could help you make one. Appropriate labelling could be something like 'WARNING: ONLY use with XXX genny AND RCD protection'

 

cheers, Pete.

~smpt~

Edited May 28, 2014 by smileypete

[BD3Bill]

 

Sounds like it's asking to be forgotten, and you're already almost halfway to a earth-neutral bonding lead anyway.

 

 

It's just a short 16a plug to 16a trailing socket lead with appropriate indelible labelling, and the earth linked to neutral at one end (or both ends for extra reliability, why not...)

 

Probably a good competent reputable experienced boatyard bloke could help you make one. Appropriate labelling could be something like 'WARNING: ONLY use with XXX genny AND RCD protection'

 

cheers, Pete.

~smpt~

 

Thanks Pete, I did suspect as much :0)

 

I have a couple of tame Sparks I know, one of which has experience with boats. One hates to ask them questions without knowing what one is talking about though!

 

The outlets on the Genny are 13 amp (Household) sockets, this doesn't matter though does it. Lead with 13amp plug one end and 16amp socket the other?

 

Cheers Bill

[smileypete]

The outlets on the Genny are 13 amp (Household) sockets, this doesn't matter though does it. Lead with 13amp plug one end and 16amp socket the other?

 

Yeah that's OK, the fuse in the plug will help stop more than 13A being drawn, and the genny should cut out before then anyway. Helps to use one of those less breakable 'tough plugs', something like:

 

http://www.screwfix.com/p/tough-black-plug-13a/68744

 

cheers, Pete.

~smpt~

Edited May 29, 2014 by smileypete

[ditchcrawler]

Would anyone agree with the practice of using a plug with a link wire from earth to neutral, in the spare socket, on a generator with two outlets ?

 

This apparently creates the necessary neutral/earth bond needed for a circuit breaker to work on an inverter genny with a floating neutral……. without ripping it to bits and permanently converting it.

 

Oh yes, I have done a lot of reading in the last 4 days folks :0)

 

Haven't found how to wire up a 'magic' hook-up lead though! :0(

 

Cheers Bill

 

( Realise that hulbond/RCD panel still needed)

What if your genny is center tapped to earth?

[Ex- Member]

 

Yeah that's OK, the fuse in the plug will help stop more than 13A being drawn, and the genny should cut out before then anyway. Helps to use one of those less breakable 'tough plugs', something like:

 

http://www.screwfix.com/p/tough-black-plug-13a/68744

 

cheers, Pete.

~smpt~

 

Good plugs those, we've used the same type but from Denmans electrical.

[by'eck]

What if your genny is center tapped to earth?

 

Good point. If so a N/E strap as mentioned above will put a direct short on a half phase of the AC output .

 

Very important the AC wiring within boat has a strap from earth to hull though. Otherwise the RCD will not offer protection.

[ditchcrawler]

Regardless of whether the hull is strapped or not, if the leakage to earth is above 30 ma the trip will go even if you don't have an earth wire back to the shore supply outlet.

[by'eck]

Regardless of whether the hull is strapped or not, if the leakage to earth is above 30 ma the trip will go even if you don't have an earth wire back to the shore supply outlet.

 

Its true that a functional RCD will trip with a current imbalance in the nominal live and neutral legs irrespective. But your body in contact with the live leg will likely complete a lethal current circuit whilst in contact with the hull as well, hence the need to ensure the hull and AC earth circuit are at same potential with a strap. Otherwise there is an admittedly unlikely situation of receiving a lethal current through your body whilst not exceeding the imbalance trip current. Its all about the RCD tripping before you die!

 

Furthermore a boat plugged into a shore supply should be considered as any other electrical device, and have an earth to its metal casing, the hull in this case, to the benefit of any passer by.

Edited May 30, 2014 by by'eck

[ditchcrawler]

 

Its true that a functional RCD will trip with a current imbalance in the nominal live and neutral legs irrespective. But your body in contact with the live leg will likely complete a lethal current circuit whilst in contact with the hull as well, hence the need to ensure the hull and AC earth circuit are at same potential with a strap. Otherwise there is an admittedly unlikely situation of receiving a lethal current through your body whilst not exceeding the imbalance trip current. Its all about the RCD tripping before you die!

 

Furthermore a boat plugged into a shore supply should be considered as any other electrical device, and have an earth to its metal casing, the hull in this case, to the benefit of any passer by.

So if you stand on a boat that is bonded and you touch a live conductor the 30ma wont flow through you?