It's shocking .... My boats melting

[OldBawley]

Had fire at an other occasion. Had been putting new bearings in the alternator. In refitting the alternator I must have forgotten to tighten the nut holding the big output cable to the diodebrighe stud. All went well for some days, then fire. The cable was glowing and the brass stud melded! See pic. A bad connection gives sparks, and they create huge ????? heat. Could repair the stud by drilling it out of the diode heat sink, tapping the whole and putting a SS bolt in it.
The alternator is an old Lucas, Max 30 Amp.
Regulation is done by hand, a combination of switches, light bulbs and a rheostat allows me to regulate the outgoing current- tension. I have a Sterling regulator but he dos not know my intentions or the weather forecast. He has no idea how much longer I will diesel, when start sailing. So, I am a smarter regulator than he is. I know witch group of battery’s is been charged, witch wind there will be on the anchorage,
We rarely need the alternator, have solar and windgen. Dieseling without tension on the field saves a lot of power.

 

[oldharry]

I should imagine that like a lot of boat people I know the rudiments of electricity but the posts on here have shown there is a lot more too it and a little knowledge can be worse thn no knowledge at all.

I have RCD's on the main components and previously they or the shore power have tripped if there is too much load. The marina I am at now is use for the bigger boats and boat shows and never once has the shore power terminal tripped no matter what I have on. W do try and limit the major things on at one time but occsionally you forget as you switch the kettle, or water heater on.

The post was intended to show that fires from electrical circuits can be easily started and if the boat is not new you may not be aware of bodged electrical work. Your boat may also have been upgraded with additional items that the original wiring was not designed for. If one person eads this and by so doing prevent a fire aboard it is worth it.

Entirely agree with your last point,.

I do hope though that your tripping "RCD's" are actually Circuit Breakers. Circuit breakers work like fuses, and cut the supply if the current draw exceeds their rating. RCDs detect whether there is a 'leak' between the supply line and earth, and trip to protect you should you touch anything that is 'live'. They will trip if heavily overloaded, but that is not their purpose.

A power tool that is damp enough to allow even a small current leak will trip an RCD even though it is working perfectly normally otherwise , which is why any marine mains installation MUST have an RCD protecting it as well as breakers. Normally only one RCD is needed to cover a whole boat.

If an appliance trips an RCD, then it is faulty, and must be regarded as dangerously unsafe for use until fixed.

 

[Scotty_Tradewind]

I strongly suggest to the OP you get the mains installation ripped out and started from scratch. It's clearly not up to standard.

The maximum current available from a shore hookup is 16A, usually less, so that's what your wiring should be rated for. Clearly it's not.

Usually 2.5mm cable throughout is all you need. What's yours wired with, bell wire?

Although Ive done a little rewiring onboard I'm not an expert, so I paid a marine electrician for an hours electrical survey on my present boat, to confirm if things looked and tested out o.k.
He strongly advised having a new 240v circuit breaker for the shore power circuit. He also suggested having a galvanic isolator fitted if I intended to spend much time in marinas etc where there may be stray currents lurking.
I eventually had him put in a new set of busbars off the batteries so that i can run fresh circuits via a new switch panel if required.
I found that the survey and the little work done, gave me a great deal more confidence and I also gave the report and a copy of work done to my insurers.

 

[Bilgediver]

Twice in the last year I have found melted wires on my boat.

On the first occasion during last winter I had heaters and a dehumidifier on. Putting the electric kettle on at the same day just finished it off.

The problem came about in a wire which had been added at a later date by someone to run additional items on th boat. It was not big enough to handle the load and therefor melted it and a small terminal block and if I had not smelt it things could have been far worse.

An electrician told me it is a common problem as boats are designed with a certain electrical system that works. Over the years people upgrade and add various items often using any old wiring they have to hand or not upgrading the existing wiring to cope with the extras.

On the second occasion it was the external shore power cable leading into the boat. That too stopped working and began to melt at the pins connecting it to the boat. Apparently over time the pins can get corroded or pitted setting up a resistance which can heat up under load as it did in my case.

I am not an electrician alhough I have now learnt the hard way of how important it is to use the correctly rated wires.

Has anyone else had similar problems, is this a problem of our own making with boats and hopefully it may make you all have a look and save yourself some danger or work in the future.

Unfortunately in the case of many boats it is as much a case of ignorance as undersized wires.

The supply to most boats is 16 amps and so this would be taken as the maximum load of the system and so sized accordingly. The danger is of having too many 13 amp sockets as in your case if using a hi speed kettle you were already close to the limit with just the kettle let alone another heater AND de humidifier.

Many folk are aware of this limitation and so rationalise accordingly IE buy slow speed kettles and keep heating load to a minimum.

You could easily put a demand of 30 amps on your 16 amp supply!!!!

 

[Nostrodamus]

Unfortunately in the case of many boats it is as much a case of ignorance as undersized wires.

Many folk are aware of this limitation and so rationalise accordingly IE buy slow speed kettles and keep heating load to a minimum.

You could easily put a demand of 30 amps on your 16 amp supply!!!!

I lot of people don'tknow this and only find out when it keeps causing problems.
In my case I did as you said and threw it away and bought a small, slower travel kettle. You live an learn.(hopefully better than dying and burn)

 

[[2574]]

Mike,

Get yourself one of these: http://www.bepmarine.com/home-mainmenu-8/product-367/600-acm-contour-matrix-ac-monitor fitted. Then it's just a matter of informing all on board to keep an eye to the AC A draw and don't exceed 16A. My wife knows that the kettle draws 11A, the immersion 4A, and the heater 4A/8A so she happily does the maths in her head. There is also an alarm to indicate overload in the instance the maths goes wrong. This in addition to the 16A cicruit breaker which I mentiond earlier in the thread. (Belt & braces me you see!)

Rob

 

[Stu Jackson]

Although Ive done a little rewiring onboard I'm not an expert, so I paid a marine electrician for an hours electrical survey on my present boat, to confirm if things looked and tested out o.k.....
I found that the survey and the little work done, gave me a great deal more confidence and I also gave the report and a copy of work done to my insurers.

Scotty,

That's a very good idea.

What I hear over and over again is the same refrain: "I don't know anything about electrical."

Just like diesel engines, none of us was born an electrician or an engine mechanic. For that matter, none of us was born a sailor. But we learned.

I also recognize different people have different aptitudes and interests. Some enjoy math(s) whilst others hate it because they just don't "get it".

Kinda true of everything in life, isn't it?

But I also suggest that if one is qualified to operate a boat, one should take the time to learn the systems that are involved, and master them for SAFETY.

Electrical is a pretty big safety item, as brought out in this topic.

If we, as skippers, can figure out sail controls and determining how big a line needs to be for a halyard or a sheet, we should be able to size wires and fuses and breakers.

There are many inexpensive books about boating electrics, some quite good. The advent of the internet has given us even more good reference sources.

Agreed that we can't all know if a PO has messed up the wiring, but when i bought our boat one of the first things I did was to start tracing wiring and understanding what I had on board.

In many cases, the quality of the installation may be a "giveaway" to the quality of the components. Most time a "rat's nest" of wiring, unlabeled and undocumented, indicates that suspicion is duly warranted.

The idea proposed about adding up wattages for A.C. power was a very good one - glad the wife can do maths in her head!

All the best.

 

[Scotty_Tradewind]

Mike,

Get yourself one of these: http://www.bepmarine.com/home-mainmenu-8/product-367/600-acm-contour-matrix-ac-monitor fitted. Then it's just a matter of informing all on board to keep an eye to the AC A draw and don't exceed 16A. My wife knows that the kettle draws 11A, the immersion 4A, and the heater 4A/8A so she happily does the maths in her head. There is also an alarm to indicate overload in the instance the maths goes wrong. This in addition to the 16A cicruit breaker which I mentiond earlier in the thread. (Belt & braces me you see!)

Rob

My friend has recently added one of these http://www.nasamarine.com/proddetail.php?prod=BMN-1_Battery&cat=15 and thinks its one of the best value for money things he's added to his yacht.

 

[mitiempo]

Scotty

The monitor you linked to and others from Victron or Xantrex are a great idea but they are DC monitors.

The Bep monitor linked to by Robih is an AC monitor - voltage, amperage, and cycles.