"Occasional" 240v

[solent clown]

We have little need of 240v on a daily basis on our boat, but I do occasionally run a drill or small grinder. To do this I use the spare battery we have on board connected to an RS components 600w inverter. The inverter is a tough "industrial" type designed for use in work vans and suchlike. I am tired of lugging it in and out of lockers, so I am going to fit it properly, and wire the battery into the charge system also.
The inverter itself has no rcd/fuses/breakers etc, just a socket, so my plan is to simply run a plug and lead into a small consumer unit (the type you buy at camping shops or chandlers) and from there just have one double socket for our occasional needs.
I am going to have to pay more atttention to the grounding now I am going to install., AC and DC, any advice/pitfalls. I have done this in many vehicles, but never in a plastic boat.
To recap, small inverter, to be fitted in a very dry locker, feeding a small twin rcd consumer unit and a double socket.
If I bond the earth to the keel am I going to rust away in 30 seconds?
The battery will be linked to the charge system with a manual switch, and charged only when I wish to to so will not be a permanent connection.

 

[ShinyShoe]

If I was wanting permanent sockets I'd install a caravan consumer unit with a caravan type 15a round pin input socket supplying it and the consumer unit supplying the socket(s).

Your input can then be anything you want - your invertor, a generator (because one day 600W will not be enough for the 750W power tool!) or a mains cable (because one day you will be alongside a marina and want all the juice you can get.

If you then run a 13amp plug to the "caravan socket" you are able to ensure never can two supplies be feeding the RCD.

However I dunno about the RCD bit - it needs an earth to work AFAIK. The invertor doesn't have a proper earth... Do you need it or do you just need the RCD earth to be "earthed" to the invertor case? (the invertor will have a point to connect earth too).

In theory earth should not be live so earthing to the sea is not going to increase galvanic corrosion. I'm more worried about when you have a fault you making the sea live and that I might happen to be swimming past!

If the RCD is effectively redundent and you have no intention of using mains power ever (where it would work as the earth would be OK, what will the consumer unit actually achieve for you? 13A plug straight to a twin 13A wall socket (could have RCD if you wanted!!) - you are only missing the fuse. There will be a fuse in the invertor and a over power cut out, and in the 13A plug (drop to 3A) and in your appliance... Only advantage of the consumer unit is it is a flick switch.

 

[solent clown]

Yes, I was planning to make up a lead, 3 pin one end, and socket the other to meet the consumer unit plug.

I was going to run the neutral from the socket back to the body of the inverter where the main external earth point is.
We will never be using shore power. RCDs are a peace of mind thing as Karen is ham fisted, I am thinking if I bond the earths and neutrals the rcds should work, and there is no chance of electrifying the water outside the boat.

 

[coopec]

If you just want it for to "run a drill or small grinder" why don't you you use a 12/18V rechargeable and run it off your battery? When my rechargeable drills, grinders stuff up I don't throw them away as I expect to wire them up and run them off the yacht 12/24V power.

Is there a reason I can't do that?

 

[solent clown]

If I were fitting a consumer unit rather than using say an extension lead occasionally then I would suggest the install should be done properly. Once done it is likely you would want to use shore powers supplies sometimes, so would have more than one source of power. As such then full pole separation of the individual power sources is essential, on both live and neutral e.g a 1 - Off - 2 two pole switch isolator (NB not a 12v battery isolator - must be rated for at least 400volts). Also the neutral from the Inverter should be grounded at the inverter, and before the isolator, ideally inside the inverter casing. Simpler place for the RCD is as a part of the consumer unit, and these are normally the size of two single pole MCBs, so a four MCB unit should provide all your needs.

Full supply isolation also means there is no risk of the supply plug from the inverter having a its prongs live, although I would do away with the 3 pin socket in favour of a more permanent fixed connection to the inverter.

Proper practice is to bond the earth to the boats bonding circuit, which is also normally connected to the -VE negative, but the bonding circuit should not be used as an active negative conductor. If you do then start to use shorepower more frequently then a galvanic isolator in the shorepower Earth line would reduce (but not eliminate) any likelihood of galvanic corrosion.

Thanks for that. You have confirmed how I plan to wire it, with the one exception that we will never be linking in to shore power. It is only a 24ft boat, and we exist happily enough on two tiny 038 batteries to run both engine and house. Heat and light are 12v LED, victorian paraffin lamps, and woollen jumpers.
We do already have a tiny inverter that plugs into the 12v aux sockets to charge phones, laptops. The utility of the larger inverter is purely for occasional power tool use, and I just want to fit it and forget it rather than be rifling through lockers, connecting the leads, running out cables - all the things that give me the excuse to put off those jobs that need doing. :encouragement:

 

[solent clown]

If you just want it for to "run a drill or small grinder" why don't you you use a 12/18V rechargeable and run it off your battery? When my rechargeable drills, grinders stuff up I don't throw them away as I expect to wire them up and run them off the yacht 12/24V power.

Is there a reason I can't do that?

I like that idea. Rather clever. But I don't have a rechargable grinder or several other tools. I do however have a large workshop of power tools 50 yards from the mooring so i shall soldier on with this plan

 

[coopec]

I like that idea. Rather clever. But I don't have a rechargable grinder or several other tools.

When the battery in a rechargeable tool is no longer rechargeable you buy a new tool as it is cheaper than replacing the battery. I'm sure if you spread the word around there'd be plenty of tools available.

Clive

 

[solent clown]

When the battery in a rechargeable tool is no longer rechargeable you buy a new tool as it is cheaper than replacing the battery. I'm sure if you spread the word around there'd be plenty of tools available.

Clive

Mate, I have lost count of how many I have thrown away at work! Now we have yachts instead of dinghys I will be more recycling minded with such things.

 

[rogerthebodger]

We have little need of 240v on a daily basis on our boat, but I do occasionally run a drill or small grinder. To do this I use the spare battery we have on board connected to an RS components 600w inverter. The inverter is a tough "industrial" type designed for use in work vans and suchlike. I am tired of lugging it in and out of lockers, so I am going to fit it properly, and wire the battery into the charge system also.
The inverter itself has no rcd/fuses/breakers etc, just a socket, so my plan is to simply run a plug and lead into a small consumer unit (the type you buy at camping shops or chandlers) and from there just have one double socket for our occasional needs.
I am going to have to pay more atttention to the grounding now I am going to install., AC and DC, any advice/pitfalls. I have done this in many vehicles, but never in a plastic boat.
To recap, small inverter, to be fitted in a very dry locker, feeding a small twin rcd consumer unit and a double socket.
If I bond the earth to the keel am I going to rust away in 30 seconds?
The battery will be linked to the charge system with a manual switch, and charged only when I wish to to so will not be a permanent connection.

I have full mains setup (inverter generator and shore power) on board but I still tend to use my battery tools as its easer and the speed of a battery is much better for drilling stainless steel than a mains drill but still can drill wood / grp if required.

I also have a battery angle grinder for the times when I need to cut or smooth while on board.

http://ryobi.co.za/product/18v-li-ion-3000mah-battery-pack-xb-3000/

http://ryobi.co.za/product/18v-li-ion-1500mah-battery-pack-xb-1500/

https://www.builders.co.za/Power-To...xI94lrloWC6-ZasTeeHXK0sEhDxzFQbwaAvceEALw_wcB

Unlike you my workshop is 600 km from my boat so I cannot just nip back to do a job or pick up a tool.

My old 12V drills where the battery have failed I have wired to run direct from 12 V. Local tool repair workshops may have some lying around as I had.

 

[lw395]

Thanks for that. You have confirmed how I plan to wire it, with the one exception that we will never be linking in to shore power. It is only a 24ft boat, and we exist happily enough on two tiny 038 batteries to run both engine and house. Heat and light are 12v LED, victorian paraffin lamps, and woollen jumpers.
We do already have a tiny inverter that plugs into the 12v aux sockets to charge phones, laptops. The utility of the larger inverter is purely for occasional power tool use, and I just want to fit it and forget it rather than be rifling through lockers, connecting the leads, running out cables - all the things that give me the excuse to put off those jobs that need doing. :encouragement:

I reckon that at some point in the future, perhpas when the boat is ashore, the temptation to plug into the shore will be powerful.
You may want to consider the next owner as well as yourself.
So, if it's possible to plug in shore power, it should be safe.

One approach is to hard wire the inverter to a socket or two via an RCD. Keep it simple.
If you need yard power, just use an extension lead with an inline rcd and stick to double-insulated mains devices.

 

[solent clown]

One approach is to hard wire the inverter to a socket or two via an RCD. Keep it simple.
If you need yard power, just use an extension lead with an inline rcd and stick to double-insulated mains devices.

yes that is what I am going to do. When it comes out of the water it will be next to one of my machine shops with power, I will just chuck a lead up

 

[PaulRainbow]

yes that is what I am going to do. When it comes out of the water it will be next to one of my machine shops with power, I will just chuck a lead up

Keep it simple. If you just have the inverter connected to the battery the negative will not be grounded, as it is in shore power, so you can't get a shock unless you touch the negative and positive at the same time. No need to run grounding wires to the keel, no worries of increased risk of galvanic corrosion, so need need for galvanic isolators. So, you need to protect against getting a shock by touching the negative and positive at the same time, plus, overload/short circuit protection.

One of these : https://www.screwfix.com/p/masterplug-rcd-adaptor/63731 followed by a lead with a 13a fuse in it, as in a bog standard extension lead.

 

[rogerthebodger]

Keep it simple. If you just have the inverter connected to the battery the negative will not be grounded, as it is in shore power, so you can't get a shock unless you touch the negative and positive at the same time. No need to run grounding wires to the keel, no worries of increased risk of galvanic corrosion, so need need for galvanic isolators. So, you need to protect against getting a shock by touching the negative and positive at the same time, plus, overload/short circuit protection.

One of these : https://www.screwfix.com/p/masterplug-rcd-adaptor/63731 followed by a lead with a 13a fuse in it, as in a bog standard extension lead.

Paul I have said this before with a non grounded inverter the third mains plug "earth pin" needs to be neutral line must be connected to the lead going to the RCD other wise the RCD will not work due to no path for the RCD trip current to flow.

This is one of the fundamental laws of electricity.

 

[solent clown]

Paul I have said this before with a non grounded inverter the third mains plug "earth pin" needs to be neutral line must be connected to the lead going to the RCD other wise the RCD will not work due to no path for the RCD trip current to flow.

This is one of the fundamental laws of electricity.

that is what I thought also re RCD, (but socket, not plug) however as I have never done this in a boat I had to ask the question.

 

[rogerthebodger]

that is what I thought also re RCD, (but socket, not plug) however as I have never done this in a boat I had to ask the question.

My inverter has a UK socket into which a fitted a UK plug and it was in that plug I connected the neutral and earth. This just saved me from opening the inverter and destroying and guarantee.

 

[PaulRainbow]

Ho hum..............

 

[rogerthebodger]

Ho hum..............

Whats your issue Paul ?

Am I right or wrong

 

[PaulRainbow]

Whats your issue Paul ?

Am I right or wrong

An RCD does not require an earth.

 

[lw395]

Paul I have said this before with a non grounded inverter the third mains plug "earth pin" needs to be neutral line must be connected to the lead going to the RCD other wise the RCD will not work due to no path for the RCD trip current to flow.

This is one of the fundamental laws of electricity.

Apart from being mangled english, that's not entirely correct.
Some codes of practice for marine wiring connect the local neutral to local earth via either a significant impedance, or some sort of fault sensor.
The object of the game is not to make an RCD trip, it's to keep things safe.

 

[PaulRainbow]

A full short circuit will blow the fuse in the supply cable ! Remember, plug in RCD>>13a fuse>>>cable to tools.

I'm not talking about wiring a house or a factory up, i'm talking about the OPs small inverter, connected to a battery, supplying a drill or grinder (or anything else he wants to plug into it).