Changes to BSS regs for RCD's ?

[Alan de Enfield]

Advice for owners – it is strongly advised that a Residual Current Device (RCD) is installed to provide

appropriate electric shock protection on a.c. systems.

 

Four boats ago I had a BSS failure due to not having an RCD fitted.

 

I pointed out that it was not compulsory and was offered a choice -

 

a ) As you have paid me already I will issue a failure and that's the end of it, or

b ) You can nip down to screw fix and get one (they are about 'a fiver') fit it, give me call and I'll come back and give you a 'pass'

 

Rather than have to pay out another £140 I just fitted one, he called into the marina the next day and without checking that it had been installed just issued the new BSS.

 

I have informed Rob@BSS of the name & details

[widebeamboy]

 

Four boats ago I had a BSS failure due to not having an RCD fitted.

 

I pointed out that it was not compulsory and was offered a choice -

 

a ) As you have paid me already I will issue a failure and that's the end of it, or

b ) You can nip down to screw fix and get one (they are about 'a fiver') fit it, give me call and I'll come back and give you a 'pass'

 

Rather than have to pay out another £140 I just fitted one, he called into the marina the next day and without checking that it had been installed just issued the new BSS.

 

I have informed Rob@BSS of the name & details

Alan, are you on the 16a or the new 32a sockets in Limehouse? I ask as I am on the new 32a ones and this has made me wonder as my first ever BSS will be due early 2017.

[gazza]

 

Your limit is a self-imposed one, by the desire to split circuits which could be 1 circuit. Instead of using 2 circuits (10A and 6A), have one circuit protected by a 16A MCB (or a 10A MCB if appropriate) then you'll be protected properly AND have (for example) 16-2 = 14A (or 10-2 = 8A) available to domestic consumption before you exceed the current supply and trip something.

No he doesn't.

 

The supply to cable to his battery charger should be 1mm to suit the 10a breaker he has fitted. Fitting a 10a breaker to the charger supply circuit does not mean it's consumption has suddenly increased by 8a leaving 6a for the rest of the boat.

 

By fitting a 10a breaker with any supply cabling smaller than 1mm is poor practice indeed.

Remember, it's the cabling not the equipment you protect.

 

ETA, splitting circuits is good practice for fault finding. It has no bearing on the maximum demand you can make on the system as others have mentioned.

Edited August 5, 2016 by gazza

[Paul C]

No he doesn't.

 

The supply to cable to his battery charger should be 1mm to suit the 10a breaker he has fitted. Fitting a 10a breaker to the charger supply circuit does not mean it's consumption has suddenly increased by 8a leaving 6a for the rest of the boat.

 

By fitting a 10a breaker with any supply cabling smaller than 1mm is poor practice indeed.

Remember, it's the cabling not the equipment you protect.

 

ETA, splitting circuits is good practice for fault finding. It has no bearing on the maximum demand you can make on the system as others have mentioned.

 

There's that much missing information on the post I answered (of Keeping Up's) that I made assumptions relating to the size of the MCBs, derived from the original complaint (that he's limited to 6A on the domestic side). I think its up to Keeping Up to confirm what his arrangement of circuit breakers and their ratings are. We're basically saying the same things but based on unwritten assumptions. I see you've made a massive assumption regarding cable size.

Edited August 5, 2016 by Paul C

[Keeping Up]

All the cabling on mine is 2.5mm Arctic. There's a 10 amp breaker on the charger, and a 16 amp breaker on the domestic circuit.

 

P'S I've not yet managed to get any further info on my friend's boat's rcd issue.

Edited August 5, 2016 by Keeping Up

[gazza]

 

There's that much missing information on the post I answered (of Keeping Up's) that I made assumptions relating to the size of the MCBs, derived from the original complaint (that he's limited to 6A on the domestic side). I think its up to Keeping Up to confirm what his arrangement of circuit breakers and their ratings are. We're basically saying the same things but based on unwritten assumptions. I see you've made a massive assumption regarding cable size.

Noni haven't, 1mm is the minimum required for a 10a breaker. It's a statement not an assumption!!

[Paul C]

Noni haven't, 1mm is the minimum required for a 10a breaker. It's a statement not an assumption!!

 

It seems to be a side issue, or a non-issue here.

[gazza]

 

It seems to be a side issue, or a non-issue here.

Ummm, it's the only issue so far as MCB's are concerned!!

 

It brings us back full circle to the nonsense the BSS bod was coming out with!

Edited August 5, 2016 by gazza

[keif's mate]

Keepingup's BSS examiner would have kittens if he looked at the Consumer unit in a modern house.

 

As Cut Hound said, has he never heard of diversity?

 

40A Shower

32A Cooker

32A Ring Final Circuit

32A Ring Final Circuit

20A Immersion Heater

16A Garage Supply

6A Lights up

6A Lights down

 

Good Lord, that is 184A. All this with a 100A Leccy Board supply fuse and 25mm2 tails!!!!

 

If memory serves me well, Diversity for domestic lighting circuits is 60% of installed load.

 

The guy that dreamed that figure up obviously didn't have kids. They know how to turn lights on but not off.!! so 100% of the lighting is on 100% of the time!!!

[Detling]

The only change I know of that may be relevant is that (I think) consumer units in houses must be in a metal box instead of a plastic box in future, but AFAIK that is not retrospective in houses. Is it being applied retrospectively in boats, or is there some other possible change in the rules here?

This agrees with what my electrician said when he rewired our house he bought and fitted the box before Christmas and did the wiring in January in order to use a plastic box as the metal ones are bigger. As an aside he said that fitting metal boxes will be shortlived as all the ones he has come across have sharp edges and in his experience (large commercial installs) damage to the insulation of wires when fitting is significant and very frequent.

For a boat they would be a nightmare as plastic doesn't rust and the ultra thin steel used would be soon gone in a salt air environment.

[Paul C]

Keepingup's BSS examiner would have kittens if he looked at the Consumer unit in a modern house.

 

As Cut Hound said, has he never heard of diversity?

 

40A Shower

32A Cooker

32A Ring Final Circuit

32A Ring Final Circuit

20A Immersion Heater

16A Garage Supply

6A Lights up

6A Lights down

 

Good Lord, that is 184A. All this with a 100A Leccy Board supply fuse and 25mm2 tails!!!!

 

If memory serves me well, Diversity for domestic lighting circuits is 60% of installed load.

 

The guy that dreamed that figure up obviously didn't have kids. They know how to turn lights on but not off.!! so 100% of the lighting is on 100% of the time!!!

 

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.

[gazza]

 

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.

Have a guess what the equivalent of the 25mm tails and 100a breaker are in the boat circuit.

 

It's not very hard and requires no lateral thinking.

 

You may use the paper to show your working out.....

[Alan de Enfield]

Alan, are you on the 16a or the new 32a sockets in Limehouse? I ask as I am on the new 32a ones and this has made me wonder as my first ever BSS will be due early 2017.

 

I'm in Kings Marina (Newark) and Hull Marina (Hull) not Limehouse.

 

It was a well known 'Midlands Surveyor' who failed my NB (for lack of RCD) in Kings marina

[nicknorman]

"Are all fuses appropriately rated"

 

If you have a circuit which has components of max. 16A rating, somewhere on that circuit there should be a fuse/MCB of that rating. Its pretty clear to me.

 

 

You can't use an RCD then feed it to a (for example) 10A + 10A MCBs because 10+10=20. But you could feed it to 10+6 MCBs. Or just have one circuit on the boat (one MCB) and it should be appropriately rated - 16A or less.

No. "Are all fuses appropriately rated" is just the title. It then goes on to explain what that means and expand on what the various checks are, and none of them relate to limiting the sum of the breakers' ratings to the current rating of the shore connector.

[Paul C]

No. "Are all fuses appropriately rated" is just the title. It then goes on to explain what that means and expand on what the various checks are, and none of them relate to limiting the sum of the breakers' ratings to the current rating of the shore connector.

 

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.

[gazza]

 

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.

So answer the question about what happens on a 6a supply then......

[GUMPY]

 

which is where the clued up bit comes in....

 

As an aside, who has enough electrical equipment onboard running at one tine to exceed a 16a supply?

I can get to a 17.5amps but it means the kettle, the toaster, the plinth heater flat out, the tv, the battery charger and the immersion heater all being on at the same time.

Me on the Barge

Washing machine

Immersion

Battery charger

25amps for a surprisingly long time.

Nothing tripped mind you my shoreline has a 16amp K rated mcb (RCD covers 3 outlets)

[gazza]

Me on the Barge

Washing machine

Immersion

Battery charger

25amps for a surprisingly long time.

Nothing tripped mind you my shoreline has a 16amp K rated mcb (RCD covers 3 outlets)

Show off

 

You'd have the ammeter gazers going nuts at MNCC, The Genny canni stand it sir

Edited August 5, 2016 by gazza

[nicknorman]

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.

No, you are putting your own interpretation on what is meant by "appropriately rated". That is fully described and explained in the text and does not reflect your personal interpretation.

 

Ever thought of becoming a BSS inspector?

[Paul C]

No, you are putting your own interpretation on what is meant by "appropriately rated". That is fully described and explained in the text and does not reflect your personal interpretation.

 

Ever thought of becoming a BSS inspector?

 

I'm playing devil's advocate - BSS examiners are putting their own interpretation on what "appropriately rated" means - with varying results. It is not fully descibed/explained in the following text, in the BSS manual. Copy and paste the text would be a good idea (so we're all on the same page....)

Edited August 5, 2016 by Paul C

[nicknorman]

I'm playing devil's advocate - BSS examiners are putting their own interpretation on what "appropriately rated" means - with varying results. It is not fully descibed/explained in the following text, in the BSS manual. Copy and paste the text would be a good idea (so we're all on the same page....)

The copy and paste text has been posted up thread a bit.

 

It's also interesting to look at ISO13297 which is "the bible" for installing ac systems in boats. It runs to 36 pages. There is a statement relating to the requirement to ensure that the rating of the over current protector doesn't exceed the current carrying capacity of the cable being protected. So that brings up the question of whether the over current protector is there to protect the conductor upstream as well as downstream. Since an over current protector can't possibly protect the conductor upstream from say a short circuit, I can't see how it could be the intention of this statement to include the current rating of the upstream cable.

 

There is quite a bit about shore socket inlets and within 36 pages, if they had wanted to surely it would be simple to specifically say that the boat's systems must not be capable of demanding more than the sockets rated current - but there is no such statement.

[GUMPY]

Show off

 

You'd have the ammeter gazers going nuts at MNCC, The Genny canni stand it sir

And that was without the aircon and microwave

[gazza]

 

I'm playing devil's advocate - BSS examiners are putting their own interpretation on what "appropriately rated" means - with varying results. It is not fully descibed/explained in the following text, in the BSS manual. Copy and paste the text would be a good idea (so we're all on the same page....)

You're also avoiding answering the two questions I posed you.

 

Again

 

What are the 100a breaker and 25mm equivalent on a boat Electrical supply?

 

What is your take on the issue of being on a 6a supply given that you think the sum of the boats circuits should be equal to the incoming supply.

 

It won't take many lines or minutes to answer those two correctly.

And that was without the aircon and microwave

The A/C sounds like heaven!

Edited August 5, 2016 by gazza

[WotEver]

So answer the question about what happens on a 6a supply then......

In the context of the post that started this spat the boat would still be fed by a 16A shore power cable, so a 16A master breaker would still protect it. The fact that the shore power would have popped 10A earlier is irrelevant.

 

Tony

What are the 100a breaker and 25mm equivalent on a boat Electrical supply?

The requested 16A incoming breaker.

 

Tony

 

I'm not saying that this interpretation is correct of course, just looking at how it could work. Diversity isn't in question, simply 'protection' for the shore power cable.

 

We really need Rob to clarify this.

[gazza]

In the context of the post that started this spat the boat would still be fed by a 16A shore power cable, so a 16A master breaker would still protect it. The fact that the shore power would have popped 10A earlier is irrelevant.

 

Tony

 

The requested 16A incoming breaker.

 

Tony

 

I'm not saying that this interpretation is correct of course, just looking at how it could work. Diversity isn't in question, simply 'protection' for the shore power cable.

 

We really need Rob to clarify this.

Oi!!

 

 

It was for PaulC to answer, his silence sums up his knowledge of the subject

 

Is Rob the BSS bod an electrician? As Nick points out the BSS is very vague and non committal on AC systems. Several have pointed out incorrect advice and demands made by BSS inspectors.

That is the point Rob needs to clarify, the inconsistent approach to inspections, not the finer points of AC systems, something which PaulC has attempted but failed dismal at.

Edited August 5, 2016 by gazza