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Post by Saltysplash on May 31, 2016 18:20:40 GMT
Over the weekend we had problems with our shore line keep tripping at the land box.
I eventually found a cut on our shoreline so we replaced the cable with a new one and the problem persisted. We then plugged our cable into a visitors socket and had no problems with it tripping so there was obviously a problem with our socket on the land.
The boatyard had a look today and found the rcd on the land as damaged/burnt. He had a look at our RCD on the boat and he said ours was too large.
The one on the boat is a 100a RCD while the shore box is 80a.
My question to the floor is, would the larger rating on the boat cause the lower rating on the shore to burn out?
I might add that we have had problems with our power tripping over a number of years with 2 different boats.
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Post by naughtyfox on May 31, 2016 18:47:31 GMT
Users Online 0 Staff, 2 Members, 9 Guests. naughtyfox, Saltysplash
Looks like you're asking me! I know nuffin' about Electrickery!
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Post by metanoia on May 31, 2016 18:49:11 GMT
Where's Nick No-all when you actually need him .................?
ETA: you probably are better off asking the floor rather than Foxy and me!
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Post by Saltysplash on May 31, 2016 18:51:32 GMT
Users Online 0 Staff, 2 Members, 9 Guests. naughtyfox, Saltysplash Looks like you're asking me! I know nuffin' about Electrickery! Go to the back of the class
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Post by naughtyfox on May 31, 2016 18:53:21 GMT
"I'd rather stay here with all the mad men than perish with the sad men roaming free"
Stay here with the mad man, then. This sad man is orf to Bed-fordshire.... night all! ZZZzzzzz.............
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Post by peterboat on May 31, 2016 18:54:38 GMT
When I worked for Edmunson electrical they always said you shouldnt have 2 rcds together but I have no idea really
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Post by metanoia on May 31, 2016 18:55:08 GMT
Bit harsh, Foxy, but goodnight ..... sweet dreams!
Sorry, Salty, I only read the thread because I thought it might be about fridges. I like fridges (or what you keep in them!).
Hopefully someone can help; good luck in getting it sorted soon.
ETA: make that VERY sorry, sir - don't want to upset the chap in that avatar
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Post by Saltysplash on May 31, 2016 19:10:52 GMT
Thats alright, it will sit here waiting for an electical wizard to appear. I understand they are like buses.
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Post by phil70 on May 31, 2016 21:09:38 GMT
Certainly not a bus, but to me it would seem incorrect to have the potential of drawing more current on the boat than the shore power pylon/point is capable of supplying, it could mean the shore power tripping simply because you are trying to draw too much. The supply from our shore power pylon is 16amp which I consider to be plenty. It is possible that the RCD on your boat is faulty, I have had this myself in the past, the RCD kept dropping out but a easy thing to change. Phil
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Post by Mr Stabby on May 31, 2016 21:19:18 GMT
What high-wattage electrical equipment do you have on the boat?
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Post by smileypete on May 31, 2016 22:20:59 GMT
Sounds to me like the shoreline RCD probably had a loose terminal connection which overheated, loose connections can cause nuisance tripping as well. There should also be an MCB (current breaker) on the shoreline bollard for over current protection, usually 16A for a typical inland boat. Ideally there should be one in the boat too, it MAY be a BSS requirement these days. RCDs are usually rated 80A or 100A or so as they're normally fitted to a domestic consumer unit in houses. Doesn't mean they trip at that current, that's just their max safe current rating. They do trip due to small earth leakage (detected as a current imbalance) as that's their job. Sounds like the boatyard bloke knows 'a bit' but not 'a lot', if it comes to blows a qualified spark will set him right. If you still get nuisance tripping when the shoreline RCD is replaced, try with a different shoreline lead and supply bollard if you can to rule those out first before looking at the boat.
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Post by JohnV on May 31, 2016 23:23:09 GMT
Only just got in and read this post, I would say the boatyard bloke knows little rather than a bit. On more modern installations you may find RCBO's which combine an MCB (overload) and an RCD (earth/imbalance) in a single module, these look like an MCB in size but have a test button as well, these will be rated in the same way as MCB's i.e. 10A, 16A, 20A etc . If it is just an RCD it's current rating is irrelevant. I doesn't matter a damn what it's rated current is, (It doesn't "trip" at that rating it is just the maximum current it can safely handle) it doesn't alter the leakage or imbalance that it's looking for (which in this case should be 30mA.) 100mA and 300mA RCD's are available but should NEVER be used for this job (and you would be unlikely to come across them anyway)
Peter mentioned being told not to have 2 RCD's in series in the same circuit. From the safety point of view this is a myth. It is spoken of as bad practice only because in most shore installations it can be a pain in the arse because both trips will see the fault and trip at the same time. If there is a trip on the boat and a trip on the bollard and both go, then the fault is probably on the boat. If only the bollard trip goes then the fault is probably with the shore lead or the bollard itself. RCD's can fail by going more sensitive but this can only be measured with a specialist meter.
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Post by naughtyfox on Jun 1, 2016 7:09:03 GMT
Slighty off topic, and I posted this earlier elsewhere, but I've got a bit of crimping to do and found this video and I thought it was well made and enjoyable to watch.
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Post by Robbo on Jun 1, 2016 8:26:50 GMT
The boatyard had a look today and found the rcd on the land as damaged/burnt. He had a look at our RCD on the boat and he said ours was too large. The one on the boat is a 100a RCD while the shore box is 80a. The boatyard is wrong. RCD's are not over current protectors. The rating on the RCD is what amps it can handle not what it cut's out at. A MCB is a over current protector and will cut supply at the rated amps (well not quite, but you get the idea). RCBO's and the like are a mixture of a RCD/MCB. The shore supply should also have a MCB which should be rated at or less than what socket is used (so 16amp for a 16amp socket). RCD - cuts out if the electric going out (Live) doesn't match the same going in (Neutral). It cuts out because the electric is going elsewhere which could be you! MCB - cuts out of the amount of power used is over the rating. Designed to protect cables.
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Post by JohnV on Jun 1, 2016 8:39:47 GMT
good post Foxy.
It is a good video especially for the smaller sizes and for insulated crimps. If you are thinking of buying a crimper for insulated crimps the ratchet type is so much superior to the "Plier" type please don't be tempted by the cheap ones. You can buy the ratchet type in any electrical wholesaler for around the £16 mark.
(but please note this is only for the ordinary car type red, blue and yellow sleeved crimps
Because on a boat you will be using fine stranded cable and fittings that are often designed for solid cable (screw terminals) to comply with latest regulations you will need another type of crimp and, unfortunately another crimp tool. this is for "bootlace crimps" These come in a range of sizes matching all the standard wire gauges. (my crimp tool cost about £40 but there may be cheaper around now) I have just had a look round and I see that RS components do a cheapo bootlace kit with a basic "plier type" crimp tool and a range of terminals for about £30 plus vat
In the video, for plain copper tube crimps he demonstrates with a CK type ratchet crimper these are fine for the smaller sizes of crimp but they only go up to 25mm (and to be honest you need arms like Hercules to do a 25mm) If you are a serious canal boater your battery bank will probably require bigger cables than this 50mm 70mm or even bigger. For these sizes you need something a lot better, ideally a hydraulic crimper which moulds a hexagonal crimp for really good connectivity. Often if you ask round you will find someone who owns one and is prepared to loan/rent it to you, my hydraulic crimper is frequently in use on these moorings (some electrical wholesalers will rent out one but this is rare) There are some manual crimpers using the "indent" as opposed to the "hex" crimp that go up to about 100mm and these can be found for round the £80 mark
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