mains The Mains Electrical Thread

[TheQ]

There needs to be a circuit to make the anodes erode, the only way I can see that happening would be for power to enter the boat somewhere, Propshaft? and then loop back to the anode for that to happen, with an external source they would have to be VERY close.

Or did the owner have a battery charger connected for sometime as that would complete the circuit, because I doubt they would have a galvanic isolator on an extention lead!! 

Also on the broads we have an interesting problem,

If you only use the boat in:

 Fresh water the anodes  should be Magniesium,

 Brackish water the anodes should be Aluminum,

Salt water the anodes should be Zinc,

 So depending on where your boat is based, depends on what type you need , the wrong type and it will erode very rapidly or not give you protection.

(There are other considerations depending on hull / prop / propshaft / outdrive, materials as well)

 

[Poppy]

1 minute ago, TheQ said:

There needs to be a circuit to make the anodes erode, the only way I can see that happening would be for power to enter the boat somewhere, Propshaft? and then loop back to the anode for that to happen, with an external source they would have to be VERY close.

Also on the broads we have an interesting problem,

If you only use the boat in:

 Fresh water the anodes  should be Magniesium,

 Brackish water the anodes should be Aluminum,

Salt water the anodes should be Zinc,

 So depending on where your boat is based, depends on what type you need , the wrong type and it will erode very rapidly or not give you protection.

(There are other considerations depending on hull / prop / propshaft / outdrive, materials as well)

 

Indeed!   It was. Since the 'guilty party' was not keen to 'fix it' , he now uses one of these  http://www.anodeoutlet.co.uk/fitting-instructions/57l-hanging-anode-range/

[TheQ]

That may be something I have to use, once I have fitted my 240V system, until I next get the boat lifted and get a permanent installation.

[BroadScot]

Quote

The regulations on Electrical installations fixed and portable are there,  But no one I've ever heard of, has their electric lawn mower or kettle checked at home ( there is no specific requirement to do so, but you are still responsible for your equipment should family or visitor get injured), 

The end of this month begining of September use to be quite busy for me testing appliances students were taking to University digs. Without a doubt, more and more each year were now double insulated.

Iain

[Vaughan]

Something I forgot to mention.

Battery chargers and especially inverters, must have a lot of ventilation and should ideally be installed right next to a hull vent. They give off a lot of heat and so it is no good boxing them away somewhere, such as under the helm seat. If they can't get rid of their heat to atmosphere, they will overheat, trip out and have to be re-set. That is if they don't burn out.

You know the more we discuss this, the more I have in the back of my mind that 220v AC and water just don't mix.

 

[BroadScot]

Quote

You know the more we discuss this, the more I have in the back of my mind that 220v AC and water just don't mix.

I can see Charlie nodding in approval !

Iain

[Bound2Please]

54 minutes ago, BroadScot said:

I can see Charlie nodding in approval !

Iain

How right you are Iain................ it has disaster written all over it....

Charlie

[Vaughan]

5 hours ago, TheQ said:

Fresh water the anodes  should be Magniesium,

Don't let anyone tell us that the Broads are fresh water - or the Canal du Midi for that matter. We have always fitted Zinc anodes and these seem to work well. We change them about every 2 years. If there seems to be about half of it left then change it, as it is actually "finished". And don't antifoul over them either!

 

[Wonderwall]

This is my take on it,probably at lot of codswallaop but here goes.

Water is not a particularly good conductor of electricity. Pure water has a very high resistance. Add salt, minerals etc then it's resistance does come down.

The path to earth for a human , in terms of electricity, is not a good one while standing on a wooden floor, floating in water , some 2 metres from the ground.

It is not dis similar to the bird on a wire scenario. If everything metal was bonded , then during a fault you would have to be in contact with the shore and a live part to then become the path to earth.

There are many people on here a lot more clued up than myself on this, so I'm sure someone will be along to put me right. I would welcome it, every day's a school day, and I've never given much thought to boat electrics before.

I think people would be surprised at the amount of domestic installations which have ran without an earth for a long time and they have been non the wiser. I'd say I come across two or three a year which have lost their earth , or never had one.

[BroadScot]

When PVC took over from lead or VIR covered cables, in the 60's wiring in brand new properties had no earth at the ceiling roses just twin and earth to the conduit box. Funny thing is, in those early days, until Appleby fitted an earth lug in the box, all we could do was make a loop on the earth apply the black sticky insulating tape to said bare earth wire, no sleeving then. Put the box screw through the light switch and tighten. Modern or what !  We did move on to washer and screw to the spare lug not much later after tHe loop method.

The materials today are so much easier and better most of the time to work with. With dry lining patress boxes used now, earthing domestic work has changed quite a lot.

The more I read this thread, the more I am enjoying reading it all.

Iain

[ranworthbreeze]

Hi Iain,

What about the introduction of Scotch Tape in the 60's in those metal tins, I had seen nothing like that before, it must have cost a fortune at the time, so much better than the cloth based tape, of course we were also using screwits or pot connectors. 

Stardrills and Rawl tools were the order of the day with the associated hammer rash, electric drills were rare on site and somewhat heavy duty, assuming you had the guts to use one, they usually snatched and wrists were at risk. I still have my joist brace (and other braces) and a roll of bits, these however have never see the light of day for many years.

No neon testers back then, just a test lamp or if you were lucky a Martindale tester for testing 415 volts, my BA spanner set cost me small fortune, likewise any of the other tools you had to buy, not many tools were provided by companies back then.

I guess you will have made some of your own tools, there was the rotary strippers for Pyro; but in many cases especially on smaller diameter cables the cutter could cut into the cores, we used to use a tool we made, it was almost like a corned beef tin key, but between 6 inches to a foot in length with a slot in the end in order to put the out copper sheath of the Pyro into.

Of course we have spoken of the wooden block for slight bends in conduit before, for bigger jobs of course we used to bender/pipe vice.

Looking back on some of my early installations we seemed to take forever just making the fixing runs for conduit or Pyro or using a stardrill for the Rawl  bolts that would hold the heavy cast fuse boards onto the walls.

Sorry for drowning on but any job just seemed to take ages.

Regards

Alan

[BroadScot]

Hi Alan,

Before hammer drills going up ladders with in our case the AEG electric gun sure was a wrist damager. The recoil was not funny in damp brickwork. A piece of cast hicky pipe that the heating lads used made me a Tbar pipe, very handy with 5/8th conduit if a tight bend was required. A dod of 6x2 with a 1.1/4" hole was ideal for offsets. 

My boss supplied taps and wrenches it was in a wooden Britool box. The 2BA and the 4BA were the two most used. He also supplied the dies for screwing conduit with the mobile vice.

The larger auger bits with a hole you you made the handle from a piece of wood. I gave all my old tools to my mates son in law including a full heavy duty socket set. I still have my wheel brace somewhere out in the garden hut !

The introduction of speed bits because of timber built houses sure speeded up boring all the holes for cabling up. I still have my star rawlbolt chisel I think? But the rawlbit tool holder is a distant memory !

I still have pieces of lead from lead covered cables as they made the best "mouse" for fishing cables inside walls. A coathanger wire was straightened and a hook made to fish the said "mouse" Thank goodness for lathe n plaster walls to route cables rewiring old Georgian and Victorian houses. 

When I pass a housing estate in Ayr I have a little chuckle to myself, as I wired every bungalow on the estste in the late 60's early 70's lol...... Happy days !

Iain

[Vaughan]

Thinking about my previous post, I would like to give a little resumé of my feelings after our discussion so far.

I have had it bashed into me all my life that you can't have "mains" power on boats and I have stood by this up until only a few years ago. I joined Crown Blue Line at the time when mobile phones were brand new and were still not common. As technical manager I resisted strongly the idea to fit inverters to charge these phones. When you plug in your phone at home, that little black box on the plug is an inverter and the phone actually charges on DC, so why not plug it in, via its own adaptor, to the DC plug on the boat? This argument held sway for a long time (and is still valid now) but we already had a lot of "stuff" on the boats, including vent fans and two big fridges, so batteries and their charging was becoming a problem. As we didn't want them running on the quay (please note!) We realised that shore power was going to be the only way forward.

However at Crown Cruisers, fitted by John Spruce in conjunction with Peachment, this was a professional installation and I can promise you that on a boat built by Crown you are as safe to use AC appliances as you would be in your own home. Maybe more so?

It is also much better on turn round days as all the boats are plugged in, ensuring they have charged batteries for the next customers and the cleaners with their vacuums don't have the risk of trailing extension leads over the water as they can plug straight into the boat. As can the mechanics if they need to use power tools.

So I am still an advocate of shore power - in this pure sense - and I still thoroughly recommend it as a solution to the modern problems on the Broads of having to run engines on the quay.

What worries me - and it seems all of us - is that boats now rely on AC equipment on board but have no shore power! Microwaves take almost 1000 watts and a ladies hairdrier well over 1000. This means high current provided by a powerful  inverter - or sometimes more than one. But are we satisfied that it is safe to do this? Has it been thought through?

I am not the only one disappointed that we have not heard from a hire yard on this thread. Surely someone is reading it? Would they not like the opportunity to describe their circuits to us, and put our minds at rest?

[Viking23]

Beware of mains electrical filters.

You find these in some IT power supplies, in Computer filtered extension leads. etc

Within the design small capacitors are placed between live to neutral, also between earth and live and earth and neutral.

So when things work well, if you loose the earth, then the capacitors act as a potential divider, and the earth becomes 120 volts ac, not enough to throw you across the room, but enough that some people can feel it. A neon screwdriver will certainly light up.

20 years ago I fitted an RS inline filter made by Schaffner, into the supply of an outside light, as the light triggered everytime something switched in the house. The filter cured it. 

However, last month we were plunged into darkness, the main RCD tripped and a 16 amp fuse blew for the garage sockets. I went into the garage where the fuse box was, and there was an acrid smell from the area where this filter was. The filter had gone into melt down, emitting loads of acrid smoke that hung around for days, and in your hair and on your hands.

I looked this filter up on the internet, and it is a common fault on Schaffner filters 20 years old, whether they were in service for long periods or not. The capacitors dry out, and short out, if this item was not earthed properly, then the outside metal light fitting could have been live.

So what other little "bombs" are we introducing into our homes.

There are a lot of CE marked equipment that has never been tested, or they have the "Golden Product" that has passed all the tests, but then items often safety items are removed to save cost. 

Thermal fuses are regularly removed in power supplies, rfi reduction filters left out too, often live and neutral are crossed over, the electrical isulation between live and neutral that gives the double insulation feature, often short across on the first spike on your mains.

Then creapage and clearance spaces are often compromised by solder whisks or items being too close to each other.

So some power supplies that look like say IPhone or iPad chargers, are often fake, and are potential fire hazzards and have a high risk of electrocution.

Buyer and user beware, however, if you stop in a hotel where they have opted for the cheapest electrical products... 

I rest my case

Richard

[ChrisB]

Hi, Richard, So those filtered extension leads are in fact working against the RCD! Am I correct? 

[Viking23]

1 hour ago, ChrisB said:

Hi, Richard, So those filtered extension leads are in fact working against the RCD! Am I correct? 

Hi Chris, you are right , but In mains filters, they use capacitors and chokes ( inductors) It is a very low leakage current,  offset by some of the current in the neutral.These filters tend to reduce radio frequecy interference from going in, or coming out of the appliance. 

Some computer spike arrestors use "transient suppressors" which clamp the spike to earth, when over a certain voltage, but it's usually so fast, the RCD doesn't respond. 

Richard

[TheQ]

Viking23's and Vaughan's points are correct, many of today devices, microwaves, induction cookers, TVs, computers,  all those little black brick powers supply's, have a filter built into their input. This is to stop radio frequencies escaping back out of the equipment, turning your wiring into radio transmitter and feeding that into other equipment.

During the 3 Rivers Race we had very bad reception from one of the guardships this proved to be every time their inverter was on. I'm betting it didn't have an earth and whatever it was powering, was causing RF interference, when I get a chance to I'll chat to the owner about it.

This reinforces my choice of option 1

Interestingly when my house earth failed, my microwave didn't become live or we were not touching another earth so didn't complete the circuit and it did become live.

Every Winter, We used to have small electronic items fail, around the house, and mobile home (different meter and phase from the house) often coinciding with an RCD trip. This stopped when the electricity poles and the mains wiring was replaced in our area.  We've not had one fail in the 2 years since this was done. So for your house, failures can be caused by outside influences. I've taken them apart to see what failed and every time it was the switched mode power supply ( which includes the filter on the same board)

As for heat, the battery chargers (CTEK) I have and the inverters I'm looking at, have their own built in fans. I'm going to mount them under the sidedecks,  highest above water level, no chance of water drips in a fibre glass boat, mounting them here would, however, form a heat trap. So I'm intending to arrange fans blowing the hot air out, these will come on whenever the chargers or inverters are switched on. Also although inverters are most efficient when run near max power I'm going to overrate the inverter so it will not get as hot and not be as stressed

 

[vanessan]

Having read all these posts, I have decided that boating is an extremely dangerous pastime and I am now going to take up knitting!

[Jim]

I was using a mains powered polisher last week and accidentally pulled the extension lead too far causing it to fall into the water. Unplugged all the shore power completely to make all safe.  Nothing tripped out though which I would have expected. 

[Jim]

46 minutes ago, vanessan said:

Having read all these posts, I have decided that boating is an extremely dangerous pastime and I am now going to take up knitting!

Then you run the risk of developing Carpal Tunnel lol 

[BroadScot]

53 minutes ago, vanessan said:

Having read all these posts, I have decided that boating is an extremely dangerous pastime and I am now going to take up knitting!

Lots of "cables" in knitting too ! 

Iain

[vanessan]

What jokers we have on this forum! I'm quite surprised nobody has warned me of sharp knitting needles. 

[BroadScot]

34 minutes ago, vanessan said:

What jokers we have on this forum! I'm quite surprised nobody has warned me of sharp knitting needles. 

Oh dear, now that IS a purl-er  This is not a stitch up...honest  ! 

Iain

[vanessan]

[Maxwellian]

Think you got the look there Iain.