Duel shore power supply's?

[Sierra2]

Another day, another problem...

 

I have been informed by a friend about the quality of the 16amp shore power supply at the Marina I plan to moor at when my boat is built.

 

In short it seems the service points supply is much less than the 16amp supply advertised and can trip with not much more than a battery charger, immersion heater and a kettle going.

 

One way around this that locals do is to pay for two metered supply's and run the shore power cable as normal and then run a second cable through a gap in a door/window/skylight to an RCD protected 4-gang socket inside the boat.

 

This is obviously unsightly and an extra potential trip hazard. It would also mean running extension leads on the interior of the boat.

 

What I have done is fit a 32amp shore line with 4mm2 (to a yet to be purchased change over switch) from the Stern of the boat that I will plug into an adaptor to take it down to 16amp.

Although I'm not planning to need it, I have also run a 16amp socket with 2.5mm2 to the rear of the wheel house where is the only space that a generator could live.

 

That is simple enough as the changeover switch would just have the usual 'SHORE POWER', 'INVERTER' and 'GENERATOR' positions.

 

The question is, is it possible to wire the Consumer unit to accept two shore supply's at the same time? My Consumer unit has two RCD's and seven MCB's.

 

Yes, I will have a qualified bod test and commission the entire set-up. I'm only asking as I would like to know if I need to run any additional wires now or if there is a simpler way of getting around the problem (other than taking the Marina to task!)

 

Thanks in advance

[Chewbacka]

If the marina has a fair few power outlets I would expect that they are using 3 phase distribution. If you were to run 2 separate supplies onto to your boat and they were on different phases then the voltage across the 2 supplies would be 415 volts. I would not want that on my boat.

As to running two supplies and then joining them together you can not do that. You could run say the charger from one supply and the kettle from the other, but this would require some complex switching. You would also still be left with the possibility of 415V across phase supplies on board.

So my view is don't do it.

[jonathanA]

I think you are over complicating things...

 

1Kw immersion call that 4 amps, most kettles are around 2Kw call that 8A a 40A charger will probalby gobble the remaining 4A so strikes me the marina supply is doing what it says ont he tin...

 

use a gas kettle or smaller charger if your on a shoreline a 20A charger will be more than adequate unless you have a massive battery bank

 

and don't bother with multiple supplies.

[Robbo]

Most quick boil kettles are around 3kw, all it takes is this and a immersion heater to go over 16amp.

[Sierra2]

 

 

If the marina has a fair few power outlets I would expect that they are using 3 phase distribution. If you were to run 2 separate supplies onto to your boat and they were on different phases then the voltage across the 2 supplies would be 415 volts. I would not want that on my boat.

As to running two supplies and then joining them together you can not do that. You could run say the charger from one supply and the kettle from the other, but this would require some complex switching. You would also still be left with the possibility of 415V across phase supplies on board.

So my view is don't do it.

 

Safety first as always so thank you for making me aware of that possibility making it a non starter. If the switching is possible would it make sense to use the shore power to just power the immersion heater and battery charger, then use the inverter to power the socket ring main for kettle, toaster, TV when required?.

 

I think you are over complicating things...

 

1Kw immersion call that 4 amps, most kettles are around 2Kw call that 8A a 40A charger will probalby gobble the remaining 4A so strikes me the marina supply is doing what it says ont he tin...

 

use a gas kettle or smaller charger if your on a shoreline a 20A charger will be more than adequate unless you have a massive battery bank

 

and don't bother with multiple supplies.

 

Hi Jonathan, I managed to get a one year old 50A charger for the price of a 20A (Sterling Pro Charge) unfortunately Bank is a planned 330aH with 130aH starter.

 

As Gas is our primary heating and cooking source it's why I'm trying to limit its usage with electric kettle/toaster while we are moored up.

 

The Propex heater does also have an AC Element for back up if we do run out of gas that I'm hoping will only need to be run on the 500w setting (given the size and insulation on the cruiser). It would be very easy for me to wire this to a plug as a fly lead and not hard wired to the consumer unit so it could be plugged in via an RCD protected extension lead to a second 16amp shore supply as others are doing.

 

Thank you all for your views, knowledgeable as always!

Edited August 13, 2015 by Sierra2

[Sierra2]

Most quick boil kettles are around 3kw, all it takes is this and a immersion heater to go over 16amp.

 

I would buy a 500w travel type kettle as I new there would be limitations. Time I do have

Edited August 13, 2015 by Sierra2

[Chewbacka]

You can sometimes find an Owl wireless electric meter on e-bay as some of the electric companies used to give them away.

Anyway they will show you your total consumption and you will be able to see how much you are using.

Just an idea.

[Sierra2]

You can sometimes find an Owl wireless electric meter on e-bay as some of the electric companies used to give them away.

Anyway they will show you your total consumption and you will be able to see how much you are using.

Just an idea.

 

Quite like that idea. Something like this? http://www.theowl.com/index.php/products/energy-moni/

[Arthur Brown]

It doesn't take much to pop a 16a breaker, especially in a "domestic" kitchen! Kettle, microwave, toaster, washing machine and charger will pop any breaker without adding computer, TV etc.

 

Yes you could take (and pay for) two bollard feeds but you don't know that they are on the same phase and 400v can be a little extra danger on a boat already running mains. You would have to be well disciplined to be certain that loads were applied safely over two feeds, which would best be spaced by a couple of metres.

[Arthur Brown]

Maplin and other like shops sell plug in meters to monitor the current consumption of appliances, maybe you could check all the items you have and monitor the consumption, or even fit a direct reading 16a AC ammeter to your mains incomer so that you can watch what current you draw and keep below the breaker trip value.

 

Live is really about usual just less electricity than you are limited to, or going out in the dark and wet to trip the bollard back on. (Worse if the breakers are in the office)

[Sierra2]

It doesn't take much to pop a 16a breaker, especially in a "domestic" kitchen! Kettle, microwave, toaster, washing machine and charger will pop any breaker without adding computer, TV etc.

 

Yes you could take (and pay for) two bollard feeds but you don't know that they are on the same phase and 400v can be a little extra danger on a boat already running mains. You would have to be well disciplined to be certain that loads were applied safely over two feeds, which would best be spaced by a couple of metres.

 

 

I suppose I could fit an automatic timer to the Immersion heater to cut it off just before I get up in the morning, back on again in the late afternoon and then off just after I get in from work in the evening?

[GUMPY]

We ditched the toaster and the electric kettle.

Reverted to grill in cooker and stove top kettle far nicer.

The kettle has the advantage that I get up to turn it on go back to bed and when it whistles my wife find it so annoying she gets up to make the tea.

[George94]

Isolate the immersion heater, and dedicate one supply to that.

 

Use the other supply for all the others.

 

Safe and simple.

[Chewbacka]

 

Quite like that idea. Something like this? http://www.theowl.com/index.php/products/energy-moni/

Yep

[ditchcrawler]

Isolate the immersion heater, and dedicate one supply to that.

 

Use the other supply for all the others.

 

Safe and simple.

Not if its on 2 phases

[Arthur Brown]

For the purposes of avoiding 400v on the boat I'd want to avoid bringing two wires onto the boat, yes a suitably competent professional can check for correct pin assignment in both supplies and whether there are two phases or just one.

 

Two comments about load

If you are on shoreline you don't need much of a charger you charge 27/7 so why 50a

You will have to suit the load to the supply so the immersion heater can go onto a time switch so that it comes on at night when the kettle is off.

[George94]

Not if its on 2 phases

 

How would that effect an isolated immersion heater?

[Sierra2]

 

How would that effect an isolated immersion heater?

 

I should clarify what others at the Marina are doing is running an extension lead (with RCD protection) into their boat and just plugging laptops, tv's, heaters or what ever. They're not doing what I suggested and trying to do it neatly by splitting the power at the consumer unit.

 

If that's dangerous (3phase or not), then I need to let them know really! (but there have been no fires, black outs or electrocutions)

[Arthur Brown]

Well you could (but I wouldn't advise it) Fit a split consumer unit and feed a separate feed into each section, sending power out in a fixed arrangement some from one pillar and some from the other. This would risk there being 400V between some lives and others which adds to hazards but doesn't make it unsafe, but maybe bad practise.

 

As for other people I wouldn't involve myself with their (non) issues unless requested. BUT just running an extension lead into the boat from a bollard doesn't meet my idea of best practise.

[Phil Ambrose]

Two thoughts, surely the 50amp charger would be in float mode when you are on hook up? And as for trying to cut back on gas usage I find a bottle lasts about 3 months for liveaboard cooking and if you are using s Propex the gas usage for these is pretty close to the figures on the data sheet so you should be able to nail it down to the day the bottle runs out.

I find an auto changeover valve very useful provided you take the trouble to check occasionally so with a spare bottle around you should have it covered.

Phil

[Sierra2]

Two thoughts, surely the 50amp charger would be in float mode when you are on hook up? And as for trying to cut back on gas usage I find a bottle lasts about 3 months for liveaboard cooking and if you are using s Propex the gas usage for these is pretty close to the figures on the data sheet so you should be able to nail it down to the day the bottle runs out.

I find an auto changeover valve very useful provided you take the trouble to check occasionally so with a spare bottle around you should have it covered.

Phil

 

Certainly it's not charging all the time as I have it 'baby sitting' my spare 78aH car battery and the 60aH starter battery from my speed boat (that is laid up at the moment). I am powering Three 15w strip lights while I'm working and also the Isotherm fridge. The draw is around 7amp but the charger only starts when it needs to.

 

I get the auto changeover valve for convenience but I'd probably want a third smaller spare bottle (that I don't have space for) as a back up if I did forget to check. As there's no risk of a shower going cold half way through and only inconvenience during cooking, I think I'm more inclined to have a manual changeover valve so I don't have to get messy with a spanner and just turn a valve to get cooking again.

 

Nice to know about the length a bottle will go, I'm new to all this as you can probably can tell!

 

What size bottle are you using Phil?

 

Chaz

[abraxus]

You can sometimes find an Owl wireless electric meter on e-bay as some of the electric companies used to give them away.

Anyway they will show you your total consumption and you will be able to see how much you are using.

Just an idea.

 

The Owl wirerless energy monitors are great, I have one connected to my incoming shorepower feed.

 

The older models have an amp setting that shows you how many amps you're using at any given time, so that you can always see how close you're getting to the 16 amp limit. Very handy when you have the water heater, cooker and heating on, and want to know if it's ok to use the kettle.

[Phil Ambrose]

 

Certainly it's not charging all the time as I have it 'baby sitting' my spare 78aH car battery and the 60aH starter battery from my speed boat (that is laid up at the moment). I am powering Three 15w strip lights while I'm working and also the Isotherm fridge. The draw is around 7amp but the charger only starts when it needs to.

 

I get the auto changeover valve for convenience but I'd probably want a third smaller spare bottle (that I don't have space for) as a back up if I did forget to check. As there's no risk of a shower going cold half way through and only inconvenience during cooking, I think I'm more inclined to have a manual changeover valve so I don't have to get messy with a spanner and just turn a valve to get cooking again.

 

Nice to know about the length a bottle will go, I'm new to all this as you can probably can tell!

 

What size bottle are you using Phil?

 

Chaz

With auto changeover you don't have to do anything because it er automatically changes from the empty bottle to the full one. Spanner only comes into play when you decide to change the empty bottle which you can do at your leisure. I have 2 x 13kg propane and also a spare 13kg propane kicking about as backup.

Phil

 

ETA checking gas bottles, fuel levels and domestic water all becomes 2nd nature after a while as does checking your battery bank, work smart and you won't run out.

Edited August 14, 2015 by Phil Ambrose

[DHutch]

2kw 'source mixing' inverter to smooth out peaks and troughs?

 

Daniel

[OldGoat]

You can't shouldn't have separate phases on the same supply pod - but you can't predict if the next pod is on the same phase or not (there's bound to be some regulation or other to control that.

 

It all sounds desperately complicated - surely it's easier to work out what goes with what - colour code that's that can be on at the same time - and stop to think before going further.

 

Boating is camping (FFS)