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Shoreline setup advice


Boat_Around_Si

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1 minute ago, billso said:

Just to add a 32a to 16a unfused cable can never pass a PAT test for very good reason.

 

Irrelevant - my boat is not a workplace, and even there Pat testing isn't even a legal requirement

 

The Electricity at Work Regulations 1989 require that any electrical equipment that has the potential to cause injury is maintained in a safe condition. However, the Regulations do not specify what needs to be done, by whom or how frequently (ie they don't make inspection or testing of electrical appliances a legal requirement, nor do they make it a legal requirement to undertake this annually).

 

Source PAT (Portable appliance testing) - HSE's answers to popular questions

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27 minutes ago, billso said:

Hi I didn't mean to suggest your lead needed to be PAT just pointed out that it could never pass one as it not safe.


I somewhat rile at people who say “safe” or “not safe”. They haven’t really thought about the nature of safety, which is not binary. Nothing is “safe”, there are only degrees of safety. So for example, is a 16A shore cable plugged into a 16A breakered bollard safe? Reasonably so, but the boat owner comes along a bit pissed, trips over the cable, bangs his head on the way down and drowns. Not so safe now! Or maybe the bollard breaker kept tripping and the previous moorer wired across it to stop that happening. Not so safe now!
 

So you have to look at the failure modes to see what hazards there are, and then decide if the hazard is significantly likely to occur, then decide how risk averse you are, then decide whether you want to do anything about it.

 

In the case of using a 32A bollard to supply a 16A cable and boat, what is the issue? Well it is that a fault between the 32A breaker and the 16A breaker inside the boat, could result in more than 16A but less than 32A flowing, which would overheat the cable.
But what sort of fault (failure mode)? The most likely one is a frayed or damaged cable. That could result in a live to earth short circuit. But the RCD will trip instantly, before the cable has time to overheat. What about a live to neutral short circuit? Well far more than 32A will flow and the bollard breaker will trip on overload nearly instantly, before the cable has time to overheat. The only failure mode that is problematical is one that allows more than 16A but less than 32A to flow. That surely is incredibly unlikely and I can’t really envisage how it could happen. Much less likely than the pissed up owner tripping over the cable and falling in to drown.

 

So you are right, connecting a 16A cable to a 32A outlet is not safe - because nothing is totally safe. But I suggest that it doesn’t present a significant reduction in safety and is therefore not worth getting excited about.

Edited by nicknorman
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Basic principle is that an overcurrent protection device protects the cable downstream so if the shore supply is protected by a 32A MCB, the cable should be rated at 32A or greater. Hence a 16A rated cable is not adequately protected from overloading.

With an RCD protection as well, any fault resulting in an unbalanced line and neutral current, i.e. a leak to earth, will trip the RCD. So in practice the 16A cable is protected in the event of damage but not overload when plugged into a 32A supply.

I do wonder if the marina's rule is also to guard against a 16A cable being tightly coiled and substantially loaded causing overheating.

 

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19 minutes ago, Tracy D'arth said:

Basic principle is that an overcurrent protection device protects the cable downstream so if the shore supply is protected by a 32A MCB, the cable should be rated at 32A or greater. Hence a 16A rated cable is not adequately protected from overloading.

 

 

If we were using 16a cable that would be a relevant statement, but as we are not using 16a cable that is a red herring.

 

The 'standard' orange shoreline cable is 2.5mm^2 which is rated at ~34 amps in air. (26 amps enclosed in conduit)

 

The cable is NOT 16 amp cable, it is simply referred to as a 16amp shoreline to denote the standard plugs / sockets used.

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21 minutes ago, Alan de Enfield said:

 

 

If we were using 16a cable that would be a relevant statement, but as we are not using 16a cable that is a red herring.

 

The 'standard' orange shoreline cable is 2.5mm^2 which is rated at ~34 amps in air. (26 amps enclosed in conduit)

 

The cable is NOT 16 amp cable, it is simply referred to as a 16amp shoreline to denote the standard plugs / sockets used.

Never said that a shoreline was 2.5mm csa cable or that it was rated at anything. The principle is correct, 16A protection for 16A cable, 32A protection for 32A cable.

The fact that the cable is rated at more than the protection is a good thing.

I don't deal in fish.

A 1.5mm csa flexible cable is rated at 16A in free air so adequate for a 16A MCB with due regard to volt drop.

2.5mm csa flexible cable is rated at 25A and 4mm csa flexible cable is rated at 32A.

Where you got 34A from for a 2.5mm csa cable I don't know, or were you just fishing for sprats as usual?

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2 minutes ago, Tracy D'arth said:

Where you got 34A from for a 2.5mm csa cable I don't know, or were you just fishing for sprats as usual?

 

 

Maybe have a look at the IEE current ratings table 4E1A

 

I agree with your 25a rating, but as usual the devil is in the detail - read the conditions under whic the 25a is achieved (in an enclosed conduit in a thermally insulating wall)

Which is as I said in my original post on the subject, and which you kindly quoted.

 

Now you can get back to your herrings !

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3 hours ago, billso said:

Using a 32a to 16a unfused lead is not a good idea and against all regs.if anything did happen to your boat it would not be insured.just seemed worth ponting out as I have seen it end badly before.

Could you point me to these regs I'd be interested in reading them for myself 

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31 minutes ago, Alan de Enfield said:

as usual the devil is in the detail - read the conditions under whic the 25a is achieved (in an enclosed conduit in a thermally insulating wall)

 

Like inside a boat where a shorepower connection is at the bow and the cable runs internally to the distribution box at the stern? :icecream: 

5 minutes ago, jonathanA said:

Could you point me to these regs I'd be interested in reading them for myself 

 

It's against all regs apparently, so just pick one at random and read it. ;)

 

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49 minutes ago, TheBiscuits said:

It's against all regs apparently, so just pick one at random and read it.

 

 

It certainly isn't against ISO 13297 "Small craft — Electrical systems — Alternating current installations"

which simply states :

 

14 Power-source options

14.1 Power for the a.c. system shall be supplied by one of the following means:

a) single shore-power cable, power inlet, wiring and components with a capacity to supply the required design system load;

b) multiple shore-power cables, power inlets, wiring and components with a capacity to supply the required design-system load;

c) inverter supplying a.c. power from the craft's d.c. system;

d) on-board a.c. generator(s) supplying the required system load;

e) combination of shore-power cable(s) and on-board generator(s) used simultaneously if the craft's circuitry is arranged such that the load connected to each source is isolated from the other in accordance with 4.6.

 

 

No mention that it should match/exceed the shore supply capability

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Even assuming 1.5mm2 cable, it will only be overloaded until a breaker trips or a fuse blows, which can be some minutes depending on the amount of small overload.

 

A fuse typically blows "instantly" at twice its rated current,  and a mcb (depending on its type rating) trips at three to five times its rated current.

 

In the case of a fault to earth, (a more likely scenario in my experience), the current flowing will be a thousand amps or more andvthe protective device will operate almost instantly. 

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Sorry to the original poster for taking this thread off topic.

 

6 hours ago, Alan de Enfield said:

 

 

If we were using 16a cable that would be a relevant statement, but as we are not using 16a cable that is a red herring.

 

The 'standard' orange shoreline cable is 2.5mm^2 which is rated at ~34 amps in air. (26 amps enclosed in conduit)

 

The cable is NOT 16 amp cable, it is simply referred to as a 16amp shoreline to denote the standard plugs / sockets used.

Hi Allen I think this has gone on enough now but here is how British standard sees it and this is the regulation we should follow about cable rating for the use we are discussing.

 

IET Wiring Regulations (BS 7671:2008+A3:2015) - SECTION 708 ELECTRICAL INSTALLATIONS IN CARAVAN / CAMPING PARKS AND SIMILAR LOCATIONS

 

BS7671 IET regulations electrical installations in caravans & motor caravans.

 721.55.2.6
Table 721 - Minimum cross-sectional areas of flexible cords and cables for caravan connection
Rated current / minimum cross-sectional area mm2

  • 16amp- 2.5mm
  • 25amp - 4mm
  • 32amp - 6mm
  • 63amp - 16mm
  • 100amp - 35mm

This is why I mentioned a16a cable.

 

The bigger problem is the 16a rated plug and socket being connected to a 32a outlet.

 

As Nick pointed out the risks are low but with the facts you can make up your own minds.

 

 

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1 minute ago, billso said:

IET Wiring Regulations (BS 7671:2008+A3:2015) - SECTION 708 ELECTRICAL INSTALLATIONS IN CARAVAN / CAMPING PARKS AND SIMILAR LOCATIONS

 

Why on earth would you quote  the BSS requirements for caravan parks bollard installation when there is already a specific ISO specification for Marinas.

 

We are talking about the lead connecting the 'marina provided bollard' with a customer provided lead to the customer provide boat.

 

 

This connecting lead is covered by 

 ISO 13297 "Small craft — Electrical systems — Alternating current installations"

which simply states :

 

14 Power-source options

14.1 Power for the a.c. system shall be supplied by one of the following means:

a) single shore-power cable, power inlet, wiring and components with a capacity to supply the required design system load;

 

I hazard a guess that you are a domestic 'technician' (as quoted in your details) rather than one who works with boat specifications which have very different requirements.

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Hi Alan i posted that reg as that is the correct BS for the cable we are discussing.

I would be very surprised if there is not more to that iso than you posted.

It seems that you are saying it is ok to use any old bit of cable and any old connector and they don't need to conform to any specification.

Could i use a bit of old speaker cable ?

I know i would not be able to on a caravan .

 

 

 

 

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1 hour ago, billso said:

I know i would not be able to on a caravan .

 

On a permanent 'static caravan' I agree (we own a caravan park and they are wired to IET requirements, & as I am no longer current on the regs we have to bring in a sparky) , but on a mobile 'touring' caravan (equivalent to a boat) can you tell me what specification refers to the 'shoreline' (lead between caravan and the bollard) and who is supposed to inspect it ?

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21 minutes ago, Keith M said:

I suggest looking at Section 721 of BS 7671 Table 721 this to my mind this is the as close as you can get to a NB. the IET suggest using 2.5 mm rated at 16 amps.

 

And that is quoted at what temperature and in what installation conditions ?

 

As I have quoted a couple of times 2.5mm^2 is 34 amps  in 'free air', in confined conduit it is much lower.

 

 

There are huge differences in performance depending on the installation, for example 'ASAP supplies' quote their 2.5mm^2 cable at 29 amps.

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The BS does state at which temperature or condition in section 721  just that 2.5 cable is rated at 16 amps so the table 721 supersedes all other tables is my interpretation. 

BS 7671 requires HO5 cable as a minimum for outdoor location.

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19 minutes ago, Alan de Enfield said:

 

And that is quoted at what temperature and in what installation conditions ?

 

As I have quoted a couple of times 2.5mm^2 is 34 amps  in 'free air', in confined conduit it is much lower.

 

 

There are huge differences in performance depending on the installation, for example 'ASAP supplies' quote their 2.5mm^2 cable at 29 amps.

Hi Alan the whole point of the temporary installation regs is that you cant go wrong if you buy an off the shelf cable from a reputable supplier.

 

There is no installation rating factors as it cant be installed .

 

And ASAP are right in that their cable is suitable for use upto 29 amps in certain situations but a shoreline for a boat is not one of them.

 

 

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One of the things that has been missed by many is that boats are often wired using garage consumer units with an RCD* feeding multiple MCB. It can then be very easy to draw more than 16amps  continuously down a 16amp cable connected to a 32amp bollard. Many boats do not have a 16amp breaker on the input just an RCD*

 

* Note I said RCD and not RCBO

 

Edited by Loddon
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4 minutes ago, Loddon said:

One of the things that has been missed by many is that boats are often wired using garage consumer units with an RCD* feeding multiple MCB. It can then be very easy to draw more than 16amps  continuously down a 16amp cable connected to a 32amp bollard. Many boats do not have a 16amp breaker on the input just an RCD*

 

* Note I said RCD and not RCBO

 

Yes I think that might be true (not in the case of our boat) but the issue there is the boat’s inadequate over current protection, rather than plugging into a 32A breakered bollard. The ISO requires over-current protection at the inlet to the boat, and boats as you describe are not compliant.

Edited by nicknorman
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On 30/01/2021 at 09:40, billso said:

 

The 10a rated cable in that extension is protected by a 10a fuse so is safe.

But is it? Whilst 10A fuses are available, and one may have been fitted by the manufacturer, the preferred fuse ratings for plug fuses are 3A and 13A, and these are all you are likely to find in the average consumer retail outlet. So if the original fuse has been replaced, it is very likely that a 13A replacement has been fitted (if it wasn't there originally).

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