Changes to BSS regs for RCD's ?

[Keeping Up]

In this case the failure was for half a dozen minor and easily correctable faults, it's just this one which puzzles me and so far all the info I have is a text from the most owner.

[WotEver]

 

Some weeks ago now 10 or more weeks ago

 

Keith

I'd suggest you try click-n-collect then. That way you've already paid for the goods and they just have to give them to you.

 

However, are you sure they weren't asking just so that you could have the discount?

[cuthound]

in the past he has adversely commented about my own installation on the grounds that the sum-total of the ratings of the breakers in the distribution box (26 Amps) is greater than the rating of the shoreline cable that feeds it (16 Amps); my contention to that is that breakers are there only to protect that which is downstream of them, and that any protection for the shoreline input must come from the on-shore supply point. He however stated that since a boater has no control over that supply point, it is his responsibility to backwards-protect the shoreline by not having a sum-total of more than 16 Amps-worth of breakers. He threatened me with a failure in the future, so I think I foresee an argument approaching!

I take it that he has never heard of diversity then?

 

It is a well established practice in electrical protection design.

 

If you add up the "apparent capacity" of the distribution breakers in any house or commercial premises, they will always add up to more that the capacity of the incoming supply.

[Chewbacka]

I take it that he has never heard of diversity then?

 

It is a well established practice in electrical protection design.

 

If you add up the "apparent capacity" of the distribution breakers in any house or commercial premises, they will always add up to more that the capacity of the incoming supply.

But the incoming supply will have a fuse of say 80~100A to protect the supply cable.

I think in the case above, the inspector feels that the total load that could be demanded is 26A passing through a 16A shore cable. If the shore supply bollard were fused at a higher current then the cable could be overloaded. So he probably wants to see a 16A incoming fuse or breaker.

 

Added - That said I have never seen a bollard with a 16A outlet with a breaker bigger than that. But then I have not looked at many bollards.

Edited August 5, 2016 by Chewbacka

[nicknorman]

But the incoming supply will have a fuse of say 80~100A to protect the supply cable.

I think in the case above, the inspector feels that the total load that could be demanded is 26A passing through a 16A shore cable. If the shore supply bollard were fused at a higher current then the cable could be overloaded. So he probably wants to see a 16A incoming fuse or breaker.

However that is outside the remit of the BSS. The shore bollard will presumably have a 16A breaker to match the 16A connector and even if not, it is pointless to relate a boat's BSS to an individual bollard that is not part of the boat.

 

But anyway the bottom line is that there is nothing in the BSS that requires a breaker that limits overall current to the shore connector's rating.

 

It certainly could be an advisory point but it's not a fail point.

Edited August 5, 2016 by nicknorman

[gazza]

Keeping Up's inspector obviously doesn't know about the 32A bollards on the Broads.

 

They usually have a bit of 'leccy left in them as not many have a 32a - 16a adaptor.

Handy for the thrifty clued up boater

 

 

I know of a 32a bollard on the Great Ouse as well.

[Chewbacka]

Keeping Up's inspector obviously doesn't know about the 32A bollards on the Broads.

 

They usually have a bit of 'leccy left in them as not many have a 32a - 16a adaptor.

Handy for the thrifty clued up boater

 

 

I know of a 32a bollard on the Great Ouse as well.

So you could have a 32A supply feeding a 16A shore cable connected to the boat with a consumer unit with 26A of demand.

Whilst this is clearly very unwise, Nicknorman is correct in that it is not a BSS 'fail'.

[gazza]

So you could have a 32A supply feeding a 16A shore cable connected to the boat with a consumer unit with 26A of demand.

Whilst this is clearly very unwise, Nicknorman is correct in that it is not a BSS 'fail'.

As i said, handy for a clued up boater, thankfully those not clued up don't tend to use them

[BEngo]

So you could have a 32A supply feeding a 16A shore cable connected to the boat with a consumer unit with 26A of demand.

Whilst this is clearly very unwise, Nicknorman is correct in that it is not a BSS 'fail'.

You can have a house ring main with as many 13 A sockets as you like despite the safe current carrying capacity of the cables being less than 54 A in the best case installation and a lot less in a typical case. Yes the ring will be protected by a 30 / 32 A fuse or breaker but they will pass much more than the rated current. Such is diversity.

 

In Alans instance the examiner is out of order and I would be involving the BSS office if he attempted a fail on the grounds stated.

 

N

Edited August 5, 2016 by BEngo

[Paul C]

I have asked the boat-owner for more info, and will try to find out what it says.

 

Also I will have a chat with the examiner; in the past he has adversely commented about my own installation on the grounds that the sum-total of the ratings of the breakers in the distribution box (26 Amps) is greater than the rating of the shoreline cable that feeds it (16 Amps); my contention to that is that breakers are there only to protect that which is downstream of them, and that any protection for the shoreline input must come from the on-shore supply point. He however stated that since a boater has no control over that supply point, it is his responsibility to backwards-protect the shoreline by not having a sum-total of more than 16 Amps-worth of breakers. He threatened me with a failure in the future, so I think I foresee an argument approaching!

 

Probably worth reading and understanding 3.5.1

[Keeping Up]

If anything in that scenario should logically be a fail (but isn't) it ought to be the very existence of a 32A to 16A adaptor which is not itself fused at 16A or less.

[Paul C]

However that is outside the remit of the BSS. The shore bollard will presumably have a 16A breaker to match the 16A connector and even if not, it is pointless to relate a boat's BSS to an individual bollard that is not part of the boat.

 

But anyway the bottom line is that there is nothing in the BSS that requires a breaker that limits overall current to the shore connector's rating.

 

It certainly could be an advisory point but it's not a fail point.

 

Yes there is, 3.5.1

[Keeping Up]

Probably worth reading and understanding 3.5.1

I have read it and I understand it. I can't see anything there to suggest a BSS fail.

Yes there is, 3.5.1

In what way does it say that?

[Paul C]

"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.

[cuthound]

Yes there is, 3.5.1

Where does 3.5.1 state that the boats system should back protect the incoming supply.

 

3.5 Fuses and circuit breakers

3.5.1 Are all a.c. and d.c. fuses and miniature circuit-breakers appropriately rated, complete and in

good condition?

R

Check the rating, completeness and

condition of all miniature circuit-

breakers (MCBs) and fuses which can be

seen.

Fuses and MCBs must be complete and free of signs of heat

damage or deterioration, and be fitted securely.

Fuses and fuse wire must be rated not greater than any rating

marked on the fuse holder

Fuse holders must contain appropriate fuses or fuse wire and not

nails, silver paper, etc.

MCBs must not be held closed by the use of tape or other devices.

Applicability - examiners are encouraged to confirm during prior dealings with the owner, the location of the

fuse box/distribution board and any in-line fuses, and to encourage their accessibility for examination. On d.c.

systems the lack of a fuse or MCB is not in itself a fail point – a.c systems are subject to a check for the

presence of a consumer unit or acceptable alternative, see 3.9.2.

Applicability – examiners are not to remove/unscrew fuses or fuse wire holders or remove miniature circuit

breakers. The checking action for fuses and miniature circuit breakers which cannot be seen without their

removal should be confined to the checks for completeness and condition.

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.

[gazza]

If anything in that scenario should logically be a fail (but isn't) it ought to be the very existence of a 32A to 16A adaptor which is not itself fused at 16A or less.

 

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.

[Paul C]

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.

 

 

 

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

 

Everybody does, because a short-circuit in a faulty appliance would cause a massive overcurrent (until the fuse blew or the MCB tripped). Oh, your equipment is 100% reliable? Light bulbs, when they blow, cause a short-duration overcurrent, most of the time when a light bulb's blown in my home I've needed to reset the MCB afterwards.

 

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.

 

Yes, they need to protect against overcurrent due to everything plugged in at the same time and being switched on. You might have the common sense to understand currents and not do this, but what if you sell the boat, then a newbie buys it, doesn't understand electricity, turna everything on and the overcurrent burns out the shoreline socket (quite possible)? He would have a valid grievance against the BSS examiner who turned a blind eye and passed the boat. I suspect most BSS examiners would cover their arse.

[gazza]

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.

 

Everybody does, because a short-circuit in a faulty appliance would cause a massive overcurrent (until the fuse blew or the MCB tripped). Oh, your equipment is 100% reliable? Light bulbs, when they blow, cause a short-duration overcurrent, most of the time when a light bulb's blown in my home I've needed to reset the MCB afterwards.

 

 

hang on!!! i'm not on about faulty equipment, im talking about the fact a few have raised the issue of 32-16a connector overloading a typical 1.5mm shoreline cable. faults with equipment are an entirely different issue.

A 2.5mm shoreine cable is a much better prospect as 16A breaker de rates it and ensures you cant get anywhere near to exceed the cable current carrying capacity

 

As you say the point about an MCB being a device to protect THE CIRCUIT CABLING ONLY seems lost on many.

 

Try a 6a bollard breaker like we have on our mooring, its like bloody Apollo 13 at times

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.

 

Everybody does, because a short-circuit in a faulty appliance would cause a massive overcurrent (until the fuse blew or the MCB tripped). Oh, your equipment is 100% reliable? Light bulbs, when they blow, cause a short-duration overcurrent, most of the time when a light bulb's blown in my home I've needed to reset the MCB afterwards.

 

Yes, they need to protect against overcurrent due to everything plugged in at the same time and being switched on. You might have the common sense to understand currents and not do this, but what if you sell the boat, then a newbie buys it, doesn't understand electricity, turna everything on and the overcurrent burns out the shoreline socket (quite possible)? He would have a valid grievance against the BSS examiner who turned a blind eye and passed the boat. I suspect most BSS examiners would cover their arse.

 

missed your edit.

 

Your last para for various reasons is a situation that would never arise for me!

Edited August 5, 2016 by gazza

[cuthound]

According to the OP the BSS examiner expects the boats electrical system to limit the incoming supply to 16A.

 

This would normally be done by a fuse or breaker in the distribution board supplying the bollard or in the bollard itself, but this method is unacceptable to the examiner, as it is outside the control of the boater.

 

By "back protection" I mean having a protective device on the boat which will trip if the load on incoming supply exceeds 16A.

[Paul C]

It seems that only a proportion of people "get it" and its also an area where BSS Examiners are being inconsistent. Would be interesting to hear from Rob@BSSOffice regarding this rule.

[gazza]

According to the OP the BSS examiner expects the boats electrical system to limit the incoming supply to 16A.

 

This would normally be done by a fuse or breaker in the distribution board supplying the bollard or in the bollard itself, but this method is unacceptable to the examiner, as it is outside the control of the boater.

 

By "back protection" I mean having a protective device on the boat which will trip if the load on incoming supply exceeds 16A.

What about in a case like ours? We most often use a 6a supply at our home mooring or when on Genny power meaning you have to be careful what's plugged in to avoid tripping it.

According to the BSS bod we'd need a supply distribution systen designed for 6a supply and a separate system for a 16a supply as the boat electrical system should protect the incomer rather than the incoming supply protecting its own cabling

 

Absolutely arse about face.

Edited August 5, 2016 by gazza

[Keeping Up]

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

[cuthound]

What about in a case like ours? We most often use a 6a supply at our home mooring or when on Genny power meaning you have to be careful what's plugged in to avoid tripping it.

According to the BSS bod we'd need a supply distribution systen designed for 6a supply and a separate system for a 16a supply as the boat electrical system should protect the incomer rather than the incoming supply protecting its own cabling

Absolutely arse about face.

Completely agree, fuses and breakers can only protect the circuit downstream of them, unless interlinked as in some large power installations.

[gazza]

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

So long as the supply cable from the breaker to the charger is capable of handling at least 10a there is no issue. You are protecting the supply cable NOT the equipment.

[Paul C]

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

 

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.