Upstream Rcd

[1boyinblue]

Hi All,

I have been working on a houseboat. All the boats are protected via individual upstream 30 m/a RCD's that are not accesible to non staff. This is all well and good, but the yard is not staffed at all times. I would like to pre-empt the upstream trip. Any ideas?

 

[Andy™]

unless its a time delay, then not much you can do.

fitting a 10mA may help, but generally either or both will trip if there is a fault

 

[1boyinblue]

Thanks Andy,

The owners of the yard are saying the RCD is protecting their supply to the boat. I have explained that overload protection is only needed for this. I do believe the £50 callout to reset the RCD may have something to do with this?

 

[Andy™]

the sockets must have RCD protection, otherwise their wiring will not comply with 7671

in addition to that, the fixed wiring on the site may also require RCD protection

so, where exactly did you get this 'I have explained that overload protection is only needed for this' from?

 

[1boyinblue]

Hi,

Hold your horses. This is my dilema. The boat is protected upstream via a 30 m/a RCD. This is a given and nessecary. My problem is that this is not a full rewire of the boat. There are a few existing problems that due to the construction of the boat are very hard to deal with. My preffered solution would be to install a new consumer unit with RCBO's for each circuit. The only problem, is that will still not prevent the upstream RCD tripping. That is my question.

 

[Sidewinder]

Hello & welcome to the forum.

You cannot get guaranteed discrimination between instantaneous type RCD's regardless of the current rating.

Not sure why you are so confident that the supply to the boat does not require an RCD.

How is the boat connected to this supply?

What are the characteristics & earthing arrangements of the shore side supply?

 

[NozSpark]

You need to have a look at section 700 of the regs,,, can't remember the exact section...

Anyway,,the basics of it is that each boat supply socket requires its own 30mA RCD protection (double pole)...

 

[steptoe]

are you allowed IT on a non naval vessel?  :C

 

[Sidewinder]

It doesn't look like you are Steps, just had a skim of EN 60092-507, though that is just pleasure craft.

Houseboats come under 7671, which is what the OP is working on.

Now, a houseboat can have a DNO supply.

 

[steptoe]

It doesn't look like you are Steps, just had a skim of EN 60092-507, though that is just pleasure craft.

Houseboats come under 7671, which is what the OP is working on.

Now, a houseboat can have a DNO supply.

TBH , I didnt think it would have been allowed, the only place Ive ever worked on it was on rigs,

thats where I learnt about it, and that thats whats used on royal naval vessels etc,

as was explained to me, you wouldnt want a gun platform to blow a fuse in the middle of an aerial bombardment,,,!!! 

the other thing im thinking here,

is this like a narrow boat?

where it will actually be sailed [can you sail without sails? :C   ] , therefore requires to be 'unplugged' from the supply?

I think its going to be impossible to get around NOT requiring the upstream RCD if that is the case,

my only solution may be to protect the feeder cable with a TD 100mA and a 30mA at the point of connection,,,,

 

[Murdoch]

Having 2 x RCD's of the same value in series makes no difference as the one at source will trip 99% of the time

Having RCBO's may help but I wouldn't guarantee it.

I think that a different approach is called for here - and that is making sure that the people who's boats are protected by the upstream 30mA RCD, have access 24 x7 to the cabinet where they are. If this means issueing you with a key then so be it - it it means relocating the RCD then this should be considered - leaving the situation as is, is not an option

 

[Marvo]

In theory you may be able to supply the boat via an on-board isolating transformer but it could get complicated very quickly. Personally I'd work on getting my own access to the RCD by hook or by crook.