Help.........my electrics keep tripping out

[boatgoball]

Hi

 

My electrics keep going off

 

have narrowed the problem down to one radial circuit that has three 240v sockets on it

 

problem seems quite bizarre

 

the end two sockets work fine but if i plug something in the first socket it trips the shorepower rcd

(it doesnt trip at my consumer unit)

 

Have tried changing the socket..there is no problem with damp and the other 2 sockets at the end of the run work fine

 

I can plug a 20watt lamp with no earth connector in the socket and it works but anything else trips it

 

Have tried bypassing the marine socket and galvanic isolator all with no success

 

 

I even tried disconnecting the earth (temporarily)from the shorepower in to see if it would still trip (it does)

 

 

At my wits end

Christmas is coming and I am reduced to running a few lights from an extension lead connected directly to shore...cant plug my battery charger in because its next to the socket that trips

 

 

 

 

Am borrowing a megger to test the cable run (its overrated arctic cable inside plastic conduit)

 

Any ideas from any electrical experts out there

[Richard Bustens]

Sounds like there is a bare bit shorting out in the box on the earth to the boat shell probably the neg wire

 

check the wires have not got bare ends in the box.

[Alistair]

Make sure the back box behind the socket is scrupulously clean.

 

Failing that check that all your connections into the back of the first socket, and indeed out to the other two, are nice and tight and snug.

 

Appeal to a deity of your choice for guidance

[Maffi]

Sounds like there is a bare bit shorting out in the box on the earth to the boat shell probably the neg wire

 

What do you base that bit of wisdom on?

[Guest]

Change the actual socket. I have had this before-I suspect it is something to do with one pole connecting before the other but have never proved it. A megger is the best way to test wirng, and if you can, borrow an RCD tester. RCD's can and do fail.

[boatgoball]

the back boxes are new made of plastic ..well insulated..not in touch with hull in any way...all connections are tight and not damp

 

(i know because ive even started taking panels off just to check the integrity of all connections....everything has been working fine for the last 6 months........wonder if there may be a fault with shore power....we have had a few electrical problems lately(power cuts..)....and I know it wasnt me to blame beacuse I was disconnected and running off inverter at the time

[boatgoball]

already changed the socket.....no difference

 

Is it possible that another boat with an earth leak could be causing the problem?

[Maffi]

I suspect it is something to do with one pole connecting before the other but have never proved it.

 

Nor will you. Current will only flow when both are connected, but this doesn't have to be concurrent.

[Maffi]

already changed the socket.....no difference

 

Is it possible that another boat with an earth leak could be causing the problem?

 

 

Have you tried pluging something in that socket that works fine in the other sockets?

Edited December 16, 2005 by Maffi

[Guest]

Nor will you. Current will only flow when both are connected, but this doesn't have to be concurrent.

So why did those horrible cheap sockets with single pole switches cause nuisance tripping in the early days of RCD's?

 

Another possibility is an accumulation of earth faults over various appliances-plug one in fine-plug next one in and trip.

[Maffi]

So why did those horrible cheap sockets with single pole switches cause nuisance tripping in the early days of RCD's?

 

No idea but I am sure you have a theory.

 

Horrible cheap single pole switch sockets are still being sold. If they were a contributory factor to nuisance tripping this would not be the case.

Edited December 16, 2005 by Maffi

[Guest]

No idea but I am sure you have a theory.

 

Horrible cheap single pole switch sockets are still being sold.

Don't deal a lot in theory have lost interest in it. Just concerned with what happens in the real world. I know that at one time the electricity board where I worked for my sins, used to frown upon RCD's feeding other RCDs. It is common to do it now of course. I supect that in this case that the RCDs should be tested before any time/money is spent.

[DHutch]

Ive been thinking about this for about 15mins, can the what would cause that, very strange

 

If its triping the marines RCD, and not your Consumer unit, then eather you consumer unit just has a stright MCB and its an earth fault, or your consumer unit has a higher current rateing, or its a combination of more than one boat.

 

- Does you consumer unit have a RCD/ RCBO/ELCB or just a plane MCB?

- How many other boats are there pluged into the same point?

- What happens if you unplug all of then, and just have your boat pluged in?

 

 

Daniel

[John Orentas]

Don't deal a lot in theory have lost interest in it. Just concerned with what happens in the real world. I know that at one time the electricity board where I worked for my sins, used to frown upon RCD's feeding other RCDs. It is common to do it now of course. I supect that in this case that the RCDs should be tested before any time/money is spent.

 

 

I tend to go along with that. I have been trying to come up with a reason that two RCD's should not be used in series, can't think of a convincing one but it doesn't feel right. I have had problems with RCD's nuisance tripping in industrial use and ended up dumping them.

[Guest]

I tend to go along with that. I have been trying to come up with a reason that two RCD's should not be used in series, can't think of a convincing one but it doesn't feel right. I have had problems with RCD's nuisance tripping in industrial use and ended up dumping them.

Tell me about it! RCDs have caused me more sleepless nights than three young kids.

[Richard Bustens]

Dont know Maffi...... he has changed the socket so it cant be that, if he plugs something into any other socket it is ok so i would have thought that lets out the RCD, that only leaves the wiring or the item concerned , but i think he has had that running in diferent socket.

 

Keep thinking back to when i got the dead short when i was soldering the pos battery terminal with mains powered soldering iron, and someone saying that neg and earth were connected if this is the cse a neh short out will blow the fuse when connected to power

[Big COL]

Hi

 

My electrics keep going off

 

have narrowed the problem down to one radial circuit that has three 240v sockets on it

 

problem seems quite bizarre

 

the end two sockets work fine but if i plug something in the first socket it trips the shorepower rcd

(it doesnt trip at my consumer unit)

 

Have tried changing the socket..there is no problem with damp and the other 2 sockets at the end of the run work fine

 

I can plug a 20watt lamp with no earth connector in the socket and it works but anything else trips it

 

Have tried bypassing the marine socket and galvanic isolator all with no success

I even tried disconnecting the earth (temporarily)from the shorepower in to see if it would still trip (it does)

At my wits end

Christmas is coming and I am reduced to running a few lights from an extension lead connected directly to shore...cant plug my battery charger in because its next to the socket that trips

Am borrowing a megger to test the cable run (its overrated arctic cable inside plastic conduit)

 

Any ideas from any electrical experts out there

 

Just a thought

 

Perhaps the first socket is OK and the second and third socket on the radial have no earth( broken between first socket and second) this will explain why the first socket trips and the rest do not. The first socket is OK running a non earthed appliance, but trips when using an earthed appliance. I would first check the earth continuity through all the sockets and then check the appliance for an earth fault.

[Tommo]

It is quite likely the RCD on the shore power is at fault and tripping to easily, or are other boats plugged into it as well. If you had a major fault on your boat your RCD would trip at the same time, assuming both are rated at 30ma.

I do come upon quite a few that are way out of calibration, we use a RCD tester with a ramp test setting to check the actual tripping current.

Another thing that causes odd tripping is reverse polarity on the live side of the RCD, in your case the one on the shore line.

The fact that it only trips on the first socket is strange, I suppose you have definitely checked you haven’t got earth and neutral reversed in the socket or on whatever you are plugging in.

Failing that the only other difference I can see is that that you will be getting very slight improvement in the earth loop impedance at the first socket.

 

Tommo

[DHutch]

Perhaps the first socket is OK and the second and third socket on the radial have no earth( broken between first socket and second) this will explain why the first socket trips and the rest do not. The first socket is OK running a non earthed appliance, but trips when using an earthed appliance. I would first check the earth continuity through all the sockets and then check the appliance for an earth fault.

Yeah, interesting thery.

 

Daniel

[boatgoball]

Well its looks like youve all been busy while I've been away

 

 

Thanks for all your replies

 

Have narrowed the problem down to my sterling battery charger

 

not sure whether it is faulty or whether it is a 12v wiring issue

 

Have unplugged it and so far nothing has tripped for the last few days

 

If i can just get my cooker fitted my radiators plumbed in and my boiler sorted and all the painting and trimming done I'll be ready for christmas

[Guest]

Electric welders can drive RCDs mad so possibly a battery charger could.

[nickfryer]

Well its looks like youve all been busy while I've been away

Thanks for all your replies

 

Have narrowed the problem down to my sterling battery charger

 

not sure whether it is faulty or whether it is a 12v wiring issue

 

Have unplugged it and so far nothing has tripped for the last few days

 

If i can just get my cooker fitted my radiators plumbed in and my boiler sorted and all the painting and trimming done I'll be ready for christmas

When there are two rcd s connected in the same supply path (series) the fault current rush, comes from the supply side, so the first rcd (shore rcd) will see the fault first and isolate the power.! Most faults connected with rcd tripping are down to a neutral earth fault? I agree you should get use of a insulation resistance tester to rule out your wiring and also check for eart continuity on all sockets.