Changes to BSS regs for RCD's ?

[Phil Ambrose]

Sock it to 'em Gazza.

Phil

[RLWP]

That is the point Rob needs to clarify, the inconsistent approach to inspections

 

That is very much what Rob does. You may not hear what he has done if it is between him and an inspector

 

Richard

Sock it to 'em Gazza.

Phil

 

Tut tut - socket, surely

 

 

Richard

[gazza]

 

That is very much what Rob does. You may not hear what he has done if it is between him and an inspector

 

Richard

 

 

Tut tut - socket, surely

 

 

Richard

I gathered that, Wotever's post seemed to read that we need Rob the BSS man to explain AC systems, is this a field (don't you dare.... ) that Rob is qualified to give advice on?

 

I'm lucky, 20 years in industrial maintenance and an old man that's a tame retired lecturer in Electrical Engineering who actually worked on the tools means I know I'm on firm ground (not that type) unlike a few of the people who have contributed to this thread.

[keif's mate]

Paul C

 

But thats the point - the 25mm2 tails are protected by a 100A fuse. There is no equivalent "master fuse" in the boat examples mentioned, thus the overcurrent protection is the sum of all the individual circuits' breakers - which is more than 100A in your case, and more than 16A (the rating of the socket and wiring) in the boat examples. If a boat had a "master" fuse or MCB of 16A (or 32A, or whatever, if the cables and socket were rated as such) then the individual ratings of each circuit are irrelevant.

 

The master fuse in the case of a shore power system is generally the 16A breaker in the supply pole. Overcurrent protection is NOT the sum of all the individual circuit breakers.

 

Consider our Green friends who tell us a 2 Megawatt wind turbine will power 1600 homes. That is wonderful, but we have to put it into context. 2 Megawatts divided by 1600 homes is 1.25 kilowatts per house. So I fire up my 10 Kilowatt shower and I am using 8 houses worth of Lectrickerty. You CANNOT sum all the Braekers/Fuses and say that is the demand of the system. END of.

[nicknorman]

Just a few further ideas, based on common sense rather than the rules/law: The thought process of some seems to be that we can't rely on the shore bollard having a 16A (or whatever) breaker. But if we are going to say that, what about the other parameters that are important in an AC supply, such as voltage and frequency? There is no requirement for a boat to have even an indication of incoming voltage, never mind an over-voltage cut-off. And ditto for frequency. One might say "but of course the voltage and frequency will be correct" but for the former, there can in fact fairly commonly be voltage outside the official range. And as for frequency, well one hopes the UK mains is 50 Hz but is there any guarantee that the shore bollard is in fact connected to the grid, as opposed to being supplied by some local generator? It is not a perfect situation and one just has to rely on the shore bollard being satisfactory.

[WotEver]

I gathered that, Wotever's post seemed to read that we need Rob the BSS man to explain AC systems...

Not at all. My post was intending to say that we need Rob to clarify the BSS guidance in this matter.

 

Tony

Just a few further ideas, based on common sense rather than the rules/law: The thought process of some seems to be that we can't rely on the shore bollard having a 16A (or whatever) breaker. But if we are going to say that, what about the other parameters that are important in an AC supply, such as voltage and frequency? There is no requirement for a boat to have even an indication of incoming voltage, never mind an over-voltage cut-off. And ditto for frequency. One might say "but of course the voltage and frequency will be correct" but for the former, there can in fact fairly commonly be voltage outside the official range. And as for frequency, well one hopes the UK mains is 50 Hz but is there any guarantee that the shore bollard is in fact connected to the grid, as opposed to being supplied by some local generator? It is not a perfect situation and one just has to rely on the shore bollard being satisfactory.

But... none of those things are 'boat systems'.

 

The only argument here, and I can see both sides of it, is that if the shore power cable forms part of the 'system' then it shouldn't be possible to overload that cable. A 16A incoming breaker neatly satisfied that requirement (if indeed it is a requirement).

 

Whether what's coming down the pipe is 265V @ 65 Hz is totally irrelevant.

 

Tony

 

Edited for tryping

Edited August 6, 2016 by WotEver

[gazza]

Not at all. My post was stating that we need Rob to clarify the BSS guidance in this matter.

 

Tony

 

But... none of those things are 'boat systems'.

 

The only argument here, and I can see both sides of it, is that if the shore power cable forms part of the 'system' then it shouldn't be possible to overload that cable. A 16A incoming breaker neatly satisfied that requirement (if indeed it is a requirement).

 

Whether what's coming down the pipe is 265V @ 65 Hz is totally irrelevant.

 

Tony

The guidance doesn't need clarifying, the inconsistent inspections and incorrect failures are the issue. Is that what you want Rob to clarify?

 

There is nothing in the guidance that a competent person can get wrong.

 

It's when people start talking guff about having to have a RCD when there is no requirement and talking about things like sum of circuits greater than 16a.

 

People like that shouldn't be installing, maintaining, inspecting or giving advice on systems that they clearly do not understand.

[WotEver]

The guidance doesn't need clarifying, the inconsistent inspections and incorrect failures are the issue. Is that what you want Rob to clarify?

Yes. You're splitting hairs. Rob needs to clarify that the guidance doesn't consider the shore power as requiring over current protection by the systems on the boat. Or otherwise.

 

Tony

[gazza]

Yes. You're splitting hairs. Rob needs to clarify that the guidance doesn't consider the shore power as requiring over current protection by the systems on the boat. Or otherwise.

 

Tony

Thanks for fleshing that out.

 

I didn't want to lump you in Paul's camp

[Sea Dog]

I'm quite enjoying this! However, I don't want Gazza to pull all his hair out, so I'm bravely pitching in to perhaps contribute to the avoidance of that!

 

It's a good little argument, but it's a parallel thread one.

 

We all stand to learn something when Rob@bss emerges to clarify the BSS guidance. Whether that guidance is clear correct and whether the examiners can or do follow it consistently is one of the threads.

 

Whether the breaker we're referring to is the there to protect the shore cable and/or circuitry supplying it or just the installation downstream of itself is the other thread. That's a bit more black and white I'd have thought.

 

I think I think what Gazza thinks: the boat's main breaker is only there to protect what's downstream; it can't predict what's upstream, so the shore breaker size is irrelevant; it doesn't have to add up to the sum of the breakers below it for reasons of diversity.

 

The only slight fly in the ointment for me is that the shore cable is ours, so, whilst my foot is in the downstream protection camp, I can see why someone may believe that this has a bearing. However, supplies at 6 amp are not uncommon, so that's where the shore cable argument hits the rocks for me.

 

Gazza, I think you're right, but keep your hands in your pockets when reading this thread and, when typing, return them there between keystrokes!

 

 

Edited to harmonise terminology (thanks Nick)

Edited August 6, 2016 by Sea Dog

[WotEver]

I've not referred to the RCD at all because that is quite clearly 'advised' and NOT compulsory. I've only pitched in with regard to the requirement or otherwise to have a master breaker to protect the shore cable.

[nicknorman]

I'm quite enjoying this! However, I don't want Gazza to pull all his hair out, so I'm bravely pitching in to perhaps contribute to the avoidance of that!

It's a good little argument, but it's a parallel thread one.

We all stand to learn something when Rob@bss emerges to clarify the BSS guidance. Whether that guidance is clear correct and whether the examiners can or do follow it consistently is one of the threads.

Whether the RCD is the there to protect the shore cable and/or circuitry supplying it or just the installation downstream of itself is the other thread. That's a bit more black and white I'd have thought.

I think I think what Gazza thinks: the boat's main RCD is only there to protect what's downstream; it can't predict what's upstream, so the shore breaker size is irrelevant; it doesn't have to add up to the sum of the breakers below it for reasons of diversity.

The only slight fly in the ointment for me is that the shore cable is ours, so, whilst my foot is in the downstream protection camp, I can see why someone may believe that this has a bearing. However, supplies at 6 amp are not uncommon, so that's where the shore cable argument hits the rocks for me.

Gazza, I think you're right, but keep your hands in your pockets when reading this thread and, when typing, return them there between keystrokes!

Well just to mention that the only thing an RCD is for is to protect humans. I think when you say RCD you really mean MCB, circuit breaker, fuse etc.

[Sea Dog]

Well just to mention that the only thing an RCD is for is to protect humans. I think when you say RCD you really mean MCB, circuit breaker, fuse etc.

Yeah, you're right of course Nick. I stuck that RCD in there since that was in the title of the thread but I've probably flawed my writings now and Gazza will be left with just a few tufts!

 

 

Edited to add I've edited the original post to remove the rogue RCD - the little tinker!

Edited August 6, 2016 by Sea Dog

[gazza]

The last few replies are ace, much more like it

 

My little un will have my hair gone miles before this forum!

 

Currently chugging towards St Ives so unlikely to get involved much today.

[MoominPapa]

Sock it to 'em Gazza.

Phil

You seem to be on the wrong forum, Phil.

 

MP.

Edited August 6, 2016 by MoominPapa

[Guest]

Edited for clarity: If the shore supply is greater than the usual 16A, what is needed is some sort of fuse/mcb in an IP box just after the shore plug in the shore line (at pillar end.) Problem solved. Better would be a fuse built into one of the pins on the shore plug similar to the old Reyroll three phase jobbies used in industry. I don't know if they are available in the type of plug we use?

Edited August 6, 2016 by Guest

[nicknorman]

What is needed is some sort of fuse/mcb in an IP box just after the shore plug in the shore line (at pillar end.) Problem solved. Better would be a fuse built into one of the pins on the shore plug similar to the old Reyroll three phase jobbies used in industry. I don't know if they are available in the type of plug we use?

I'm not sure that we do need that if the boat is plugged into a pukka shore bollard. It will have a 16A (or less) breaker. If it is plugged into say a 13A socket then you will have a 13A fuse in the plug.

[Guest]

I'm not sure that we do need that if the boat is plugged into a pukka shore bollard. It will have a 16A (or less) breaker. If it is plugged into say a 13A socket then you will have a 13A fuse in the plug.

agree 100%. If there is a 16A breaker behind the pillar supply there is no need for any further breaker. I was thinking more along the lines of those who have encountered 32 Amp supplies. Apologies for confusion, post edited for clarity.

Edited August 6, 2016 by Guest

[Justme]

An issue that I have, is that one of the breakers supplies only a Sterling 30A battery charger, max draw from the mains of around 2A but it's switch-on surge will trop any MCB of less than 10A (even an ultra slow one) so I have to use a 10A breaker for it in addition to the domestic circuit breaker. I do not wish to limit my domestic consumption to 6A

 

 

Fit a C or D curve one of a lower value.

[Justme]

 

I think we're all agreed that there is no requirement to protect (via fuse/circuit breaker) anything not on the boat, but there is a requirement that the fuse(s)/circuit breaker(s) are APPROPRIATELY rated - ie rated to protect the hookup cable, its connector, the boat's shoreline connector, the wiring from this to the consumer unit. The vast majority of connectors are rated at 16A.

 

 

The cable protection needs to be up stream of the cable not down stream. So the fuse should be in the 16 amp plug that is fitted to the bollard with the 16amp fuse in it.....

[ditchcrawler]

What do you mean "back protect the incoming supply"? It seems to be something you've invented.

 

The job of the fuse/MCB on a boat, and the inspection of it by the BSS examiner, is to protect the boat's wiring against overcurrent. That's all of it, including the socket and the bit before the consumer unit, and the bits after it ie to the sockets and permanently wired mains electrical devices.

 

 

And how will a breaker there protect the incoming plug and wiring to the MCB if a fault occurs between the plug and the MCB? This may have been answered as I am only on page 3 so far.

[Robbo]

And how will a breaker there protect the incoming plug and wiring to the MCB if a fault occurs between the plug and the MCB? This may have been answered as I am only on page 3 so far.

It won't but that's not what it's theirfore, just like a RCD is not designed for an overcurrent. The downstream MCB won't detect faults upstream but it will protect the upstream cable if you switch on too many devices. Other things can do this as well such as the Victron combi and isolation transformers.

 

The shore supply should be protected as well, but you may have no control over this. It's one of the reasons why IT's and Combi's are used a lot for boats who visit multiple country's a lot as the shore supply can be hit and miss.

[jddevel]

Having just finished a domestic referb and had the electrics "signed off" I can certainly confirm that in a domestic situation a consumer unit that is currently plastic does not according to my electrician have to be up graded to a metal one but can understand the logic in it being advised. One interesting situation is that in a house situation sometime ago it was decided that consumer units for the benefit of the disabled

should be no higher than 1200mm. They soon changed that though I suspect because they then realised that

they were in the reach of childrens little fingers!!!

[Guest]

Having just finished a domestic referb and had the electrics "signed off" I can certainly confirm that in a domestic situation a consumer unit that is currently plastic does not according to my electrician have to be up graded to a metal one but can understand the logic in it being advised. One interesting situation is that in a house situation sometime ago it was decided that consumer units for the benefit of the disabled

should be no higher than 1200mm. They soon changed that though I suspect because they then realised that

they were in the reach of childrens little fingers!!

With so many homes flooding in certain areas, I would suggest they should all be high up. Socket outlets too. Loads of houses have suffered damage to the electrical systems around our way during floods last Christmas.

Edited August 7, 2016 by Guest

[Alan de Enfield]

Having just finished a domestic referb and had the electrics "signed off" I can certainly confirm that in a domestic situation a consumer unit that is currently plastic does not according to my electrician have to be up graded to a metal one but can understand the logic in it being advised. One interesting situation is that in a house situation sometime ago it was decided that consumer units for the benefit of the disabled

should be no higher than 1200mm. They soon changed that though I suspect because they then realised that

they were in the reach of childrens little fingers!!!

 

When we had our house built, the sockets had to be 'almost half way up the wall' and the light switches 'almost half way down the wall' so that disabled / wheelchair users could reach them.