3 amp fuse in FCU for boiler

[JohnW2]

If you consider that the FCU to a boiler is meant to be the single point of isolation for the central heating system which includes the boiler, ancillary wiring, pump, room thermostat etc - often wired in 0.75mm² or 1mm² then perhaps this argument can go away.

I suspect that those who want to argue would only stop arguing if you could indicate what creates a requirement for a CH system to have a ('dedicated') single point of isolation. As far as I am aware, BS7671 does not require anything (other than the installation as a whole) to have a single point of isolation, so you'd probably have to look elsewhere.

As I and others have said, it's all a bit moot, since I personally don't recall having seen any CH in recent times that was not supplied via by a BS1363 socket/plug or FCU (hence a BS1362 fuse). The argument has really all been about whether manufacturers should be 'requiring' something that at least some people regard as 'unnecessary' (even if it's virtually always done!).

Kind Regards, John

 

[mwatsonxx]

Try "electricity at work act" if your running out of ideas.

 

[JohnW2]

Try "electricity at work act" if your running out of ideas.

I didn't realise that imposed a requirement for isolators of individual circuits or sub-circuits in domestic installations.

Kind Regards, John

 

[mwatsonxx]

I didn't realise that imposed a requirement for isolators of individual circuits or sub-circuits in domestic installations.

Kind Regards, John

What is a domestic installation? EWA does not apply to a diy spark working in his own home. But it does apply to a professional spark working in someones home, because it becomes a place of work.

 

[JohnW2]

What is a domestic installation? EWA does not apply to a diy spark working in his own home. But it does apply to a professional spark working in someones home, because it becomes a place of work.

It does, but that professional can isolate whatever he is working on at the CU. In any event, isn't it more likely to be a plumber or heating engineer working on a boiler than an electrician?

Are you suggesting every hard-wired piece of equipment in a domestic installation must have its own dedicated isolator?

Kind Regards, John

 

[ericmark]

As to single point of isolation then why can't a 3A double pole MCB be used? Why a 3A fuse and not a MCB? Also as to single point well mothers central heating has at least 5 independent supplies, 230 volt at the boiler, I don't know if this also feeds the thermostat receivers, but also pair of batteries in each wireless thermostat and in each wireless TRV head so at least 5 independent supplies.

It clearly makes sense to have an overload device, but why should it need to be a fuse? I have seen the three pole switches used for extractor fans supplied with locks and bracket to lock off the supply, however in the main with a switched FCU all you can do is lock off the line by withdrawing the fuse and dropping a lock through the fuse carrier, this is OK with a TN-C-S supply, but not with a TT supply, today you can get RCBO with double pole switching single width although the overload sensing is only on the line, so with a dedicated supply you could use a 4 amp RCBO which could be locked off at the consumer unit, since double pole not single this would be better than a 3 amp fuse. However it would seem not a permitted method.

Now I have seen where a semi-conductor fuse not a MCB is required, however the fuse in the plug is hardly a semi-conductor fuse, with a 4A RCBO and a 3A fuse I am sure the 4 amp RCBO will trip well before the fuse ruptures.

 

[ban-all-sheds]

Don't bother, Ban, he's loving every minute of it, waiting with glee for the next response to his drivel.

And in the meantime we have to suffer his lies.

The more people that report him, and get his trolling and lying stopped, the sooner the site might actually do that.

 

[SimonH2]

As to single point of isolation then why can't a 3A double pole MCB be used? Why a 3A fuse and not a MCB? Also as to single point well mothers central heating has at least 5 independent supplies, 230 volt at the boiler, I don't know if this also feeds the thermostat receivers, but also pair of batteries in each wireless thermostat and in each wireless TRV head so at least 5 independent supplies.

And all but (possibly, you aren't sure) one of them being batteries, and the supplied equipment being physically connected to ... nothing at all. So isolating the mains is enough - you don't need to remove the batteries in the other equipment to work on the (say) boiler. And if you want to work on one of the battery powered items, then you don't need to isolate the mains to the other stuff.

 

[ericmark]

And all but (possibly, you aren't sure) one of them being batteries, and the supplied equipment being physically connected to ... nothing at all. So isolating the mains is enough - you don't need to remove the batteries in the other equipment to work on the (say) boiler. And if you want to work on one of the battery powered items, then you don't need to isolate the mains to the other stuff.

So if after removing a radiator the non isolated electronic TRV turns on and allows rusty water to escape that's OK? I have argued many times over isolation, I would isolate the electric power, only to find a pneumatic motor spinning, so for a boiler to have a single point of isolation it will require an electric valve to cut off the gas, which I assume could as with pneumatic power actually cause more danger than it removes. I have seen where concrete has poured over some one because the air was dumped when the E-Stop was pressed and the valve was not shut at that point of time.

My point is that it is near impossible to have a safe single point isolation, so that can't really be reason for 3A fuse.

 

[JohnW2]

How many have banned me? none.

There's a first time for anything!

Kind Regards, John

 

[mwatsonxx]

Are you suggesting every hard-wired piece of equipment in a domestic installation must have its own dedicated isolator?

Every piece of equipment and system should have an obvious visible means of isolation.

 

[mwatsonxx]

There's a first time for anything!

Kind Regards, John

What a surprising response

 

[JohnW2]

Every piece of equipment and system should have an obvious visible means of isolation.

Does that, in your expert opinion, include such things as luminaires?

Kind Regards, John

 

[mwatsonxx]

in your expert opinion

Thanks for the appreciation

 

[ban-all-sheds]

Hey BAS, lets have some real honesty

OK, as you wish, here is some real honesty:

With three conditions that he chooses to ignore....

Which are?

You know what they are, and they have'nt changed in the past 40 years.

Please show which requirements EFLI has chosen to ignore.

see above

An unacceptable response.

You said "With three conditions that he chooses to ignore".
Will you please have the decency to show what those are, instead of repeatedly evading the question.

I'm not evading anything, I've answered 2 or 3 times.

#85 Is not an answer to the question in #82 asking which are the 3 conditions EFLI has chosen to ignore.

#87 - "see above" means "see #85". #85 is not an answer to the question asking which are the 3 conditions EFLI has chosen to ignore, and therefore #87 is not an answer to the question in #86.

So you have not answered the question even once.

That means that your assertion in #91 is untrue, and as you know you have not said which three conditions EFLI has chosen to ignore, you know it is untrue.

Writing things which you know to be untrue makes you a liar.

Stop lying.