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Post by JohnV on Mar 1, 2019 7:55:51 GMT
What sort of fuses do you have? If the “continental” type (ie a plastic tubular “slug” with soft metal ends, gripped between a pair of springy contacts) I’d give those a wiggle and see if the lights get brighter. They suffer from corrosion and bad connections. Thinking about this problem after I went to bed (I know .... sad isn't it ) I don't think that could possibly be the problem, for the resistance to be low enough for the lights to still work but to go out when a comparatively small load is added in parallel doesn't add up ...... dim yes, out no. (unless the fuse has the capacity to light up like a light bulb and still survive) There has to be something else going on here and we don't have the basic information needed to solve it. One thought I had last night was "were the wires by the bed actually for a light fitting" I wonder if in fact they were some form of remote dimming circuit....... I think we are possibly looking at the scenario where something has been added at some time, has failed and then (the bane of my existence) only partly removed. I wonder if there was a remote control/dimmer control fitted there but the actual module is still in the lighting circuits line. Without Welly doing a full check round his lighting circuit ( probably not a bad idea but now might not be the right time), I would think the best thing would be to re-terminate those wires and tuck them away as they were. Then run two nice new wires direct from the fuse panel via a low value fuse (if no spares add it to an existing circuit but please mark it for the benefit of future owners/electricians) and have a cup of tea and forget all about it
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Post by Deleted on Mar 1, 2019 7:57:37 GMT
If the light switch is designed for AC house operation then might it have a capacitor in there to prevent spikes? If so wouldn’t that block any DC current? don't think so .... never come across a switch with a built in capacitor .... and anyway that still doesn't make sense It would if it was in series! Anyway lots of ideas so far. I’m sure we’ll find out the real cause soon.
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Post by Andyberg on Mar 1, 2019 7:58:36 GMT
What sort of fuses do you have? If the “continental” type (ie a plastic tubular “slug” with soft metal ends, gripped between a pair of springy contacts) I’d give those a wiggle and see if the lights get brighter. They suffer from corrosion and bad connections. Thinking about this problem after I went to bed (I know .... sad isn't it ) I don't think that could possibly be the problem, for the resistance to be low enough for the lights to still work but to go out when a comparatively small load is added in parallel doesn't add up ...... dim yes, out no. (unless the fuse has the capacity to light up like a light bulb and still survive) There has to be something else going on here and we don't have the basic information needed to solve it. One thought I had last night was "were the wires by the bed actually for a light fitting" I wonder if in fact they were some form of remote dimming circuit....... I think we are possibly looking at the scenario where something has been added at some time, has failed and then (the bane of my existence) only partly removed. I wonder if there was a remote control/dimmer control fitted there but the actual module is still in the lighting circuits line. Without Welly doing a full check round his lighting circuit ( probably not a bad idea but now might not be the right time), I would think the best thing would be to re-terminate those wires and tuck them away as they were. Then run two nice new wires direct from the fuse panel via a low value fuse (if no spares add it to an existing circuit but please mark it for the benefit of future owners/electricians) and have a cup of tea and forget all about it Definately the way to go!👍
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Post by Deleted on Mar 1, 2019 8:03:55 GMT
If all was well without the 2 pole switch in the circuit then surely if it is just a switch (no other components fitted to it) then the problem must be the switch, or it was wired differently or a fault developed in the circuit after attempting to fit the switch. (e.g poor connection somewhere).
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Post by Deleted on Mar 1, 2019 8:08:19 GMT
What sort of fuses do you have? If the “continental” type (ie a plastic tubular “slug” with soft metal ends, gripped between a pair of springy contacts) I’d give those a wiggle and see if the lights get brighter. They suffer from corrosion and bad connections. Thinking about this problem after I went to bed (I know .... sad isn't it ) I don't think that could possibly be the problem, for the resistance to be low enough for the lights to still work but to go out when a comparatively small load is added in parallel doesn't add up ...... dim yes, out no. (unless the fuse has the capacity to light up like a light bulb and still survive) There has to be something else going on here and we don't have the basic information needed to solve it. One thought I had last night was "were the wires by the bed actually for a light fitting" I wonder if in fact they were some form of remote dimming circuit....... I think we are possibly looking at the scenario where something has been added at some time, has failed and then (the bane of my existence) only partly removed. I wonder if there was a remote control/dimmer control fitted there but the actual module is still in the lighting circuits line. Without Welly doing a full check round his lighting circuit ( probably not a bad idea but now might not be the right time), I would think the best thing would be to re-terminate those wires and tuck them away as they were. Then run two nice new wires direct from the fuse panel via a low value fuse (if no spares add it to an existing circuit but please mark it for the benefit of future owners/electricians) and have a cup of tea and forget all about it I think you're probably right with that. That bit of wiring is something of an unknown quantity and I could be mucking around with it for eternity. I'm going to run another pair of wires this weekend. Thanks for the help so far!
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Post by JohnV on Mar 1, 2019 8:17:07 GMT
Similar theme: I have 375w of solar feeding a 30a Tracer mppt controller. I'd like to introduce a switch close to the controller to isolate the panels from the controller. The controller doesn't have a switch, design flaw imho, given that you are supposed to connect the controller to the batteries first. The only way to achieve this at the moment is to either cover the panels, do it at night or remove a connecting wire from the controller. All Heath Robinson. Anyway, the only 12v switches I can find are big and ugly, isolator type things. I want something relatively small and neat. Would a cooker switch designed for 240v do the job? It's just for occasional use. If so, would a cooker switch accept the cable? I think it's 5mm, solar stuff I bought from Bimble. www.cclcomponents.com/imo-dc-isolator-16a-1500vdc-2-pole?gclid=Cj0KCQiAzePjBRCRARIsAGkrSm6NAPrpotSkw5FTw203XIvJ8zYWDu3lksFBnV48MRFELALhA09-2B8aAk6UEALw_wcBa possibility for you ....... the big problem with ac switches on dc is that the contacts burn when making/breaking contact under load. Many of the old fashioned wiping blade ac switches/isolators are fine on dc but they are mostly large, ugly and ancient. very few modern switches give a dc rating in their spec sheet. With boat lighting circuits domestic types are cheap enough and if they fail early ..... so what. With an isolator you need to make your own judgement call ........ my 1Kw array is isolated by a 240v 60 A rotary isolator and I accept the fact that it running outside it's design spec (I had a couple in my junk box and I objected to paying out for something else when it might only be used once or twice)
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Post by JohnV on Mar 1, 2019 8:20:38 GMT
If all was well without the 2 pole switch in the circuit then surely if it is just a switch (no other components fitted to it) then the problem must be the switch, or it was wired differently or a fault developed in the circuit after attempting to fit the switch. (e.g poor connection somewhere). all of these are possibilities but tracking them down is another matter ....... as regards "putting the switch in the circuit" it is in effect a parallel circuit being added and if you go through the possible effects, turning existing lights on and off doesn't make sense
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Post by Deleted on Mar 1, 2019 9:04:50 GMT
If all was well without the 2 pole switch in the circuit then surely if it is just a switch (no other components fitted to it) then the problem must be the switch, or it was wired differently or a fault developed in the circuit after attempting to fit the switch. (e.g poor connection somewhere). all of these are possibilities but tracking them down is another matter ....... as regards "putting the switch in the circuit" it is in effect a parallel circuit being added and if you go through the possible effects, turning existing lights on and off doesn't make sense That’s If the new circuit WAS added in parallel as opposed to in series with something else (which I think Tony was suggesting). Even in parallel, if the new circuit has a very low resistence somewhere, it could dim the lights just because of the voltage drop on the battery. As an aside, when I fitted LED lights everywhere on my boat, there was one I just couldn’t get working. After a while I twigged that that particulat bulb holder was wired with reverse polarity. Being a diode (LED), I had to switch the wires around. Low behold it worked!
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Post by JohnV on Mar 1, 2019 9:31:43 GMT
all of these are possibilities but tracking them down is another matter ....... as regards "putting the switch in the circuit" it is in effect a parallel circuit being added and if you go through the possible effects, turning existing lights on and off doesn't make sense That’s If the new circuit WAS added in parallel as opposed to in series with something else (which I think Tony was suggesting). Even in parallel, if the new circuit has a very low resistence somewhere, it could dim the lights just because of the voltage drop on the battery.
Dimming the lights possibly but turning them out means the voltage drop has to be high but the load you are adding is small, so extremely unlikely. If the circuit was being added in series it would not turn the series load (lights) off .... it would turn them on harder
As an aside, when I fitted LED lights everywhere on my boat, there was one I just couldn’t get working. After a while I twigged that that particulat bulb holder was wired with reverse polarity. Being a diode (LED), I had to switch the wires around. Low behold it worked!
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Post by Telemachus on Mar 1, 2019 9:41:55 GMT
One should bear in mind that a bad connection does not necessarily behave like a pure resistor.
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Post by Deleted on Mar 1, 2019 9:42:55 GMT
That’s If the new circuit WAS added in parallel as opposed to in series with something else (which I think Tony was suggesting). Even in parallel, if the new circuit has a very low resistence somewhere, it could dim the lights just because of the voltage drop on the battery.
Dimming the lights possibly but turning them out means the voltage drop has to be high but the load you are adding is small, so extremely unlikely. If the circuit was being added in series it would not turn the series load (lights) off .... it would turn them on harder
As an aside, when I fitted LED lights everywhere on my boat, there was one I just couldn’t get working. After a while I twigged that that particulat bulb holder was wired with reverse polarity. Being a diode (LED), I had to switch the wires around. Low behold it worked! I agree that in parallel for the lights to dim, the load would have to be big (or dare I say the battery might be on its way out or a bad contact somewhere). If in series with a light (which I thought Tony was suggesting) I would have thought the effect on the light would be to make it much dimmer or not work at all. It wouldn’t explain why all the lights dimmed though as they should all be connected to the ring in parallel. If I’m talking crap please tell me, I’m happy to learn.
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Post by Mr Stabby on Mar 1, 2019 9:46:57 GMT
Imagine the following. We have a 12v battery, a 12v lamp, and two lengths of wire. We connect the 12v lamp to the 12v battery using the two lengths of wire. It illuminates. We now cut the feed wire (or the return wire, it really doesn't matter) and place an on/off switch in the circuit. Oh, I do hope you've got your boat wired up with some of the switching in the negative (return) side of your various DC circuits, . . and I hope someone is there to take a photo of it when it goes up in flames ! I see. So when I go away cruising, and I disconnect my car battery so that the alarm doesn't drain it, I'd better make sure I disconnect the right terminal otherwise it will spontaneously combust while I'm away?
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Post by JohnV on Mar 1, 2019 10:12:36 GMT
Oh, I do hope you've got your boat wired up with some of the switching in the negative (return) side of your various DC circuits, . . and I hope someone is there to take a photo of it when it goes up in flames ! I see. So when I go away cruising, and I disconnect my car battery so that the alarm doesn't drain it, I'd better make sure I disconnect the right terminal otherwise it will spontaneously combust while I'm away? This is not a go at you, nor a case of leaping to another's defence but just what can happen (and possibly showing why I can be paranoid about some things) A ship I was joining had a new piece of equipment installed as part of the emergency equipment. The power was routed to it by a double pole switch only connected in the positive supply. The negative supply was taken directly from the emergency battery bank. The unit itself was bolted to the equipment room bulkhead. I was standing in front of the unit (which was switched off when not at sea) when we first started cargo handling at the dockside in Buenos Aires. There was a fault on one of the winches which proceeded to earth itself through the nearest route which was through the new piece of equipment. The panel fuses in the front of it melted and exploded blowing molten brass into my face. fortunately the molten metal missed my eyes but the flash (like arc eye) blinded me and the flame seared off my eyebrow and my sideburn on one side. None of this would have happened if the unit had been wired up correctly through the double pole switch. I spent a very uncomfortable few days in the hospital having frequent eye irrigation until they were sure there was no permanent damage. The only redeeming feature of that time was that I ended up going out with one of the (very pretty) nurses
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Post by Telemachus on Mar 1, 2019 10:14:54 GMT
I see. So when I go away cruising, and I disconnect my car battery so that the alarm doesn't drain it, I'd better make sure I disconnect the right terminal otherwise it will spontaneously combust while I'm away? This is not a go at you, nor a case of leaping to another's defence but just what can happen (and possibly showing why I can be paranoid about some things) A ship I was joining had a new piece of equipment installed as part of the emergency equipment. The power was routed to it by a double pole switch only connected in the positive supply. The negative supply was taken directly from the emergency battery bank. The unit itself was bolted to the equipment room bulkhead. I was standing in front of the unit (which was switched off when not at sea) when we first started cargo handling at the dockside in Buenos Aires. There was a fault on one of the winches which proceeded to earth itself through the nearest route which was through the new piece of equipment. The panel fuses in the front of it melted and exploded blowing molten brass into my face. fortunately the molten metal missed my eyes but the flash (like arc eye) blinded me and the flame seared off my eyebrow and my sideburn on one side. None of this would have happened if the unit had been wired up correctly through the double pole switch. I spent a very uncomfortable few days in the hospital having frequent eye irrigation until they were sure there was no permanent damage. The only redeeming feature of that time was that I ended up going out with one of the (very pretty) nurses The fundamental problem there was fuses that were not fit for purpose, or not installed with adequate protection.
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Post by JohnV on Mar 1, 2019 10:24:08 GMT
This is not a go at you, nor a case of leaping to another's defence but just what can happen (and possibly showing why I can be paranoid about some things) A ship I was joining had a new piece of equipment installed as part of the emergency equipment. The power was routed to it by a double pole switch only connected in the positive supply. The negative supply was taken directly from the emergency battery bank. The unit itself was bolted to the equipment room bulkhead. I was standing in front of the unit (which was switched off when not at sea) when we first started cargo handling at the dockside in Buenos Aires. There was a fault on one of the winches which proceeded to earth itself through the nearest route which was through the new piece of equipment. The panel fuses in the front of it melted and exploded blowing molten brass into my face. fortunately the molten metal missed my eyes but the flash (like arc eye) blinded me and the flame seared off my eyebrow and my sideburn on one side. None of this would have happened if the unit had been wired up correctly through the double pole switch. I spent a very uncomfortable few days in the hospital having frequent eye irrigation until they were sure there was no permanent damage. The only redeeming feature of that time was that I ended up going out with one of the (very pretty) nurses The fundamental problem there was fuses that were not fit for purpose, or not installed with adequate protection. The fuses were fit for the purpose ..... they weren't installed with adequate protection ...... the twat who installed it had not used both sides of the supplied double pole isolator Maybe to clarify, I should add that the equipment concerned was manufactured by a reputable marine equipment manufacturer as a standard item for ships. it was a Lloyds approved item that I came across several times during my career at sea and was more than adequately protected against any possible internal fault or fault of the equipment that should have been connected to it. It was purely the failure of the installer to wire as per manufacturer's instructions that caused the problem. The actual fault and the voltages/load applied were from a totally different bit of kit and the route the power took was complicated and incredibly unlikely ..... but that's what it did and would have been prevented by a double pole switch being wired correctly It was during the era of "glass encapsulated space charge technology devices" (valves) otherwise the surge round the ship could have wiped out a lot of semiconductors.
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