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Post by Telemachus on Mar 2, 2019 9:14:57 GMT
That’s called hull bonding, not earthing. Unless you are a vampire, you probably don’t have a lot of earth on your boat! commonly known as the ground plane ...... or earth ........ You are simply being pedantic over terminology which is common use in standard text books I am being pedantic over the misuse of word, common or otherwise, that gives rise to confusion in the minds of people who struggle to understand electrics. Why use the same word to describe a protective circuit not normally carrying current, and the normally current-carrying half-circuit of a 12v (etc) dc system? The English language has plenty of words to choose from and using the same word for both is both lazy and confusing (and wrong). But anyway if you recall the original discussion it was about whether it was important on safety grounds to switch a 12v lighting circuit used to feed a router, in the positive or negative. Of course the convention is to switch the positive but from a safety point of view it doesn’t matter. Meanwhile Tony was hysterically over-egging the argument to say that switching the negative would result in it all going up in flames.
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Post by TonyDunkley on Mar 2, 2019 10:21:21 GMT
commonly known as the ground plane ...... or earth ........ You are simply being pedantic over terminology which is common use in standard text books I am being pedantic over the misuse of word, common or otherwise, that gives rise to confusion in the minds of people who struggle to understand electrics. Why use the same word to describe a protective circuit not normally carrying current, and the normally current-carrying half-circuit of a 12v (etc) dc system? The English language has plenty of words to choose from and using the same word for both is both lazy and confusing (and wrong).But anyway if you recall the original discussion it was about whether it was important on safety grounds to switch a 12v lighting circuit used to feed a router, in the positive or negative. Of course the convention is to switch the positive but from a safety point of view it doesn’t matter. Meanwhile Tony was hysterically over-egging the argument to say that switching the negative would result in it all going up in flames.Whatever you may think about using the same word for one side of a low voltage DC circuit and a protective circuit for high voltage, fact is, that's what happens in the real world, and any automotive or marine electrician, or welder, worth their job title would know precisely what is meant by the terminology that John and I have used. Go back and read what I said about switching installed in DC earth returns, and you'll see that what I actually said was very different from what you've just quoted. I generally get quite angry with anyone who misquotes me or tries to credit me with their own half-baked ideas, but now I find myself regarding your increasingly weird posts as mildly amusing peeks into the strange and perhaps rather sad world you inhabit. I think you would fit in well, and be infinitely more happy and contented, as a full time CWDF Moderator. Why don't you give it a try ?
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Post by Deleted on Mar 2, 2019 11:11:32 GMT
Reason for not switching the -VE is stray current corrosion; Gibbo's thoughts on isolators in the -VE, I realise that a lot of it is main isolator specific but some does equally apply to individual circuits. smartgauge.co.uk/whereiso.htmlI think that the OP has tapped into a switch circuit rather than a main 12v feed and has the router in series with the lamps hence sometimes lamps coming on dim and sometimes not at all.
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Post by Andyberg on Mar 2, 2019 12:27:25 GMT
‘Return’ or earth should technically be known as ‘ Mid point’ due to DC feed being able to be either positive or negative. 👍
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Post by Telemachus on Mar 2, 2019 13:08:38 GMT
Reason for not switching the -VE is stray current corrosion; Gibbo's thoughts on isolators in the -VE, I realise that a lot of it is main isolator specific but some does equally apply to individual circuits. smartgauge.co.uk/whereiso.htmlI think that the OP has tapped into a switch circuit rather than a main 12v feed and has the router in series with the lamps hence sometimes lamps coming on dim and sometimes not at all. Yes gibbo did make that argument, and it has some merit though it is fairly tenuous. As we know, there are lots of boats with one isolator in the negative to isolate both domestic and leisure batteries. But in any case that argument is completely inapplicable to the case we are discussing.
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Post by Telemachus on Mar 2, 2019 13:14:51 GMT
I am being pedantic over the misuse of word, common or otherwise, that gives rise to confusion in the minds of people who struggle to understand electrics. Why use the same word to describe a protective circuit not normally carrying current, and the normally current-carrying half-circuit of a 12v (etc) dc system? The English language has plenty of words to choose from and using the same word for both is both lazy and confusing (and wrong).But anyway if you recall the original discussion it was about whether it was important on safety grounds to switch a 12v lighting circuit used to feed a router, in the positive or negative. Of course the convention is to switch the positive but from a safety point of view it doesn’t matter. Meanwhile Tony was hysterically over-egging the argument to say that switching the negative would result in it all going up in flames.Whatever you may think about using the same word for one side of a low voltage DC circuit and a protective circuit for high voltage, fact is, that's what happens in the real world, and any automotive or marine electrician, or welder, worth their job title would know precisely what is meant by the terminology that John and I have used. Go back and read what I said about switching installed in DC earth returns, and you'll see that what I actually said was very different from what you've just quoted. I generally get quite angry with anyone who misquotes me or tries to credit me with their own half-baked ideas, but now I find myself regarding your increasingly weird posts as mildly amusing peeks into the strange and perhaps rather sad world you inhabit. I think you would fit in well, and be infinitely more happy and contented, as a full time CWDF Moderator. Why don't you give it a try ? Boats don’t have what you misguidedly call “earth returns” so I can only assume that your repeated use of the term in the context being discussed is due to your creeping dementia. As to CWDF mod, how do you know I’m not already?
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Post by Jim on Mar 2, 2019 16:25:28 GMT
My boat is wired with positive feeds and negative returns, nothing going to the Hull, though there may be a wire to ground in the outboard. Should I have a negative bond to the Hull in this case? I can't see the need electrically.
I also have a 1.2k inverter, how does this affect the situation. Boat is due first BSC after major works shortly so I may need to make alterations.
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Post by thebfg on Mar 2, 2019 16:45:21 GMT
Have we answered the OP yet?
I have a similar question but wont ask yet due to confusion
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Post by Telemachus on Mar 2, 2019 17:02:31 GMT
Have we answered the OP yet? I have a similar question but wont ask yet due to confusion We have answered the OP, although the question keeps changing! Yes sorry about the confusion, unfortunately there are some on here with a smattering of relevant knowledge who want to apply irrelevant criteria to the discussion. Anyway, you could always start a new thread. Just don’t mention “earth” unless it’s an AC mains question!
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Post by JohnV on Mar 2, 2019 17:25:56 GMT
Reason for not switching the -VE is stray current corrosion; Gibbo's thoughts on isolators in the -VE, I realise that a lot of it is main isolator specific but some does equally apply to individual circuits. smartgauge.co.uk/whereiso.htmlI think that the OP has tapped into a switch circuit rather than a main 12v feed and has the router in series with the lamps hence sometimes lamps coming on dim and sometimes not at all. been out working today (doing electrics ) and just catching up I would agree with much of that but we were actually talking about double pole switching ...... not just switching the negative. whereas Gibbo was talking about single pole switching in the negative line only. As a result the argument is irrelevant incidentally the lights don't come on at all which is the puzzling bit ..... just dimming would make sense
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Post by Deleted on Mar 2, 2019 18:17:30 GMT
Reason for not switching the -VE is stray current corrosion; Gibbo's thoughts on isolators in the -VE, I realise that a lot of it is main isolator specific but some does equally apply to individual circuits. smartgauge.co.uk/whereiso.htmlI think that the OP has tapped into a switch circuit rather than a main 12v feed and has the router in series with the lamps hence sometimes lamps coming on dim and sometimes not at all. been out working today (doing electrics ) and just catching up I would agree with much of that but we were actually talking about double pole switching ...... not just switching the negative. whereas Gibbo was talking about single pole switching in the negative line only. As a result the argument is irrelevant incidentally the lights don't come on at all which is the puzzling bit ..... just dimming would make sense There was one point where switching the -VE was being discussed/suggested hence my posting that its a bad idea. Similar resistive loads in series is predictable, both will be 50% Led drivers and a psu in a router is not predictable it may be 50/50% it may be 10/90% all depends on how drivers and psu react with each other.
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Post by bamber on Mar 2, 2019 19:19:04 GMT
So what should I call the Earth connection on my inverter output?
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Post by Telemachus on Mar 2, 2019 19:28:11 GMT
So what should I call the Earth connection on my inverter output? Earth connection.
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Post by bamber on Mar 2, 2019 19:41:14 GMT
But it's connected to a stud fitted to the hull next to my battery negative terminal hull bonding stud. You've already pointed out that I can't refer to the battery negative connection as "earth", So why is it ok to call the inverter earth connection "Earth" when they are effectively connected to the same point? Just asking 🤔
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Post by Mr Stabby on Mar 2, 2019 19:51:16 GMT
Whatever you may think about using the same word for one side of a low voltage DC circuit and a protective circuit for high voltage, fact is, that's what happens in the real world, and any automotive or marine electrician, or welder, worth their job title would know precisely what is meant by the terminology that John and I have used. Go back and read what I said about switching installed in DC earth returns, and you'll see that what I actually said was very different from what you've just quoted. I generally get quite angry with anyone who misquotes me or tries to credit me with their own half-baked ideas, but now I find myself regarding your increasingly weird posts as mildly amusing peeks into the strange and perhaps rather sad world you inhabit. I think you would fit in well, and be infinitely more happy and contented, as a full time CWDF Moderator. Why don't you give it a try ? Boats don’t have what you misguidedly call “earth returns” so I can only assume that your repeated use of the term in the context being discussed is due to your creeping dementia. Careful Nick, or you'll be receiving a letter from his imaginary no-win, no-fee libel lawyer.
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