electric fan heater into my bathroom

[MoonMan2]

Efficiencyman, thanks for your response. From double pole switch, I am to connect the RCD switch, then the FCU and finally the electric heater? Is this correct?

Ban-all-shed, I do honestly appreciate your concern for my safety. Please remember though that this is a DIY forum and people can post here to get hopefully expert advice. I have been very specific with my questions and have required clarification a few times, the reason for this is I want to be very sure that what I am doing is correct.

In saying that, I am not arrogant about this either, if I decide after getting advice on this forum that I am not confident enough to do it then I will admit defeat and get an electrician and probably watch him do the job and learn.

I notice you haven't actually given me any advice on how to do the job, I would certainly listen to you if you did.

 

[riveralt]

I notice you haven't actually given me any advice on how to do the job, I would certainly listen to you if you did.

I kinda know what that advice will be.

 

[JohnW2]

I kinda know what that advice will be.

Indeed - but he's already given the OP that advice!

Kind Regards, John

 

[ban-all-sheds]

Efficiencyman, thanks for your response. From double pole switch, I am to connect the RCD switch, then the FCU and finally the electric heater? Is this correct?

Is your supplementary equipotential bonding OK?

If you install an RCD where efficiencyman says, and you get a L/E fault upstream of it, what will the potential of the extraneous conductive parts in the bathroom with respect to the exposed ones rise to until the fault is cleared by the circuit protective device?

Please remember though that this is a DIY forum and people can post here to get hopefully expert advice.

Which you did, and which you received. Along with advice which was not so sound.

I have been very specific with my questions and have required clarification a few times, the reason for this is I want to be very sure that what I am doing is correct.

You should not carry out work like this by simply following instructions without genuinely understanding why.

And people here should not be encouraging you to follow instructions to put-this-wire-in-that-hole without you having a genuine understanding of why.

I notice you haven't actually given me any advice on how to do the job, I would certainly listen to you if you did.

Learn what is involved.
Learn what protective devices are called (hint - they are not "thingys").
Learn what the differences are between MCBs, RCDs and FCUs.
Learn how to choose the type(s) and rating(s) of the one(s) you need.
Learn about earthing and bonding.

 

[MoonMan2]

ban-all-sheds, do you really think it is appropriate to criticise others providing advice considering YOU aren't actually providing any?

You have an awful lot to say except actually providing instruction on how to do this job. One could wonder why....??

We are all waiting for your expertise....!!

 

[MoonMan2]

Got a double pole switch with integrated 13A fuse.

Attached this switch in parallel to existing circuit in cupboard adjacent to bathroom.

Used 10A, 2 core flex to connect existing circuit to new double pole switch to fan heater.

Got fan heater running perfectly at 1kw. Heats up bathroom in no time! though can be changed with internal switch to 2kw.

Happy it's all working.

Thanks to all who provided useful information.

PS. Now tempted to change MCB in CU to B20 so I can have immersion heater and 1kw fan on at same time.

 

[ban-all-sheds]

ban-all-sheds, do you really think it is appropriate to criticise others providing advice considering YOU aren't actually providing any?

You have an awful lot to say except actually providing instruction on how to do this job. One could wonder why....?

Why?

Because I am fundamentally opposed to the idea of providing instructions for people to blindly follow without actually understanding why.

I did give you advice and assistance, and it all revolved around you developing your competence.

 

[ban-all-sheds]

Now tempted to change MCB in CU to B20 so I can have immersion heater and 1kw fan on at same time.

How are you preventing them from both being on at the same time now?

 

[MoonMan2]

The fan heater is connected to the same circuit as the 3kw immersion heater. That means it would be drawing a current of around 17A if both appliances were on at the same time.

The MCB is only 16A, so I assume it would trip it both were on.

Yes, you have spotted the weakness of this set up, there is no prevention mechanism other than me ensuring that both are NEVER on at the same time. The switches for the immersion heater and fan heater in the cupboard both have neon lights on them when switched on, so hopefully that will help.

The solution of course is to replace the B16 MCB with a B20.

 

[JohnW2]

The fan heater is connected to the same circuit as the 3kw immersion heater. That means it would be drawing a current of around 17A if both appliances were on at the same time. ... The solution of course is to replace the B16 MCB with a B20.

Although one should not have loads greater than the rating of an MCB, a 16A one would not actually trip at 17A - it would allow about 18A to flow 'indefinitely', and much higher currents than that for moderate times, without tripping. However, as you say, what should happen is that the MCB should be upgraded to 20A.

However, there is another issue to think about. The fan heater presumably plugs into a socket. Although it is currently a 1kW one, someone in the future may plug in a 2kW, or even 3kW, heater (or some other large load), so that the total load on the circuit might become nearer to 26A. If the 1kW heater were 'permanently wired in' (no socket), and the MCB were upgraded to 20A, then that possibility obviously could not arise.

Kind Regards, John

 

[ban-all-sheds]

The MCB is only 16A, so I assume it would trip it both were on.

So you are doing electrical design work without understanding the characteristics of protective devices.

Yes, you have spotted the weakness of this set up

Actually I spotted a fundamental one 33 days ago.

 

[MoonMan2]

JohnW2, the heater is permanently wired in. I can change it to a 2kw heater by use of a switch inside the fan heater though. If doing that, it would take the load up to 21.7A. If I wish this option should I replace with a 25A MCB?

 

[JohnW2]

JohnW2, the heater is permanently wired in. I can change it to a 2kw heater by use of a switch inside the fan heater though. If doing that, it would take the load up to 21.7A. If I wish this option should I replace with a 25A MCB?

That would depend upon a number of factors, not the least being whether the cable used to wire the circuit is (taking into account the way it is routed/installed) is adequate for currents >20A - which is far from being a foregone conclusion. (and that would be assuming that you can find a 25A MCB to fit your CU).

Kind Regards, John