Power Shower - FCU

[nick_r]

I have just installed a MIRA power shower that needs a 3amp FCU. Can you take the feed to the FCU from the lighting circuit? as it looks a real nightmare to take up the boarding that make up the floor!

 

[ZenStalinist]

I believe you can, I have a boiler, which was installed by a CORGI installer, not myself mind you, on an FCU from a 6 amp circuit. I do not know whether this should or should not have been done.

Though it is usually considered proper practice to use a clock connector on a lighting circuit:

This is fitted with a 2 amp fuse, 1 amp fuses are available. What wattage is your pump? A 2 amp fuse would probably be enough. I know the last power shower we had ran at 9 volts, and I think the ELV side of things was fitted with a 15 amp fuse...
So 1 amp would probably do the job on the LV side (in the clock connector). The reason it would say 3 amp is because that is the smallest rated standard fuse that can go in an FCU. The clock connectors use smaller sized fuses.

Only problem I can think of with this is that the wire comes out of the front.

 

[securespark]

I would not use a clock connector, nor would I tap off the lighting circuit.

MK advise me that aclock connector is only designed to feed 2A maximum.

Lighting circuits are not designed for a load such as this.

What is the rating of the appliance?

And what about RCD protection? Do the manufacturers suggest this?

 

[ZenStalinist]

If it is anything like the power shower we had, RCD protection won't make a scrap of difference. Most power showers are ELV, fed via a transformer. They don't take too much power... should be fine from a lighting circuit...

But yeah, good point, if there is mains going into the shower itself, I'd reccomend RCD protection.

 

[AdamW]

Also wouldn't a power shower offer an inductive load to the circuit? This might bring something to the party...

A power shower is usually rated at somewhere between 0.75 horsepower to 1.5 horsepower, which would be 560W to 1100W. This means you will need a fuse somewhere between 2.4A and 4.8A. If yours is an integrated bolt-to-the-wall power shower (as opposed to a separate pump) then I would think that it will still draw more than 2A. So you will need that 3A FCU.

A 2A clock connector? What kind of clocks do people own! 460 watts?!

When you are doing the nightmare work to get the power shower powered, just keep remembering how great it will feel being able to shower with such vigour later on.

 

[plugwash]

btw you can get 1A and 2A fuses for fcus

i think farnell sell them

 

[nick_r]

So is that a yes no or maybe?[/img]

 

[ZenStalinist]

The Mira Event XS says it must be connected via an RCD also, so putting it on the lighting circuit is not an option.

If it is the Mira Extreme shower, I'd say it should be okay to put it on the lighting circuit. Mira power showers draw only 150watts, shouldn't cause problems.

Remember not to use a switched FCU in the bathroom though.

I don't know whether it really has to be fused at all, being on the lighting circuit... Like I said, if you want closer protection, you could use a clock connector.

 

[nick_r]

Thanks for the reply.

Just checked the install manual....

"The mains supply must be 230-240v at 50Hz connected to the appliance via a double pole switched 3 Amp fused connection unit with a minimum 3 mm contact seperation gap in each pole.

A 30mA RCD must be fitted. This may be part of the consumer unit or a seperate unit.

Absorbed power - Approximately 150W under normal working conditions"

So....

The main consumer unit has an RCD already fitted, The FCU has a 3Amp fuse in it so is it ok to tap into the light circuit in the loft and if so can I just connect the FCU incoming supply directly to one of the ceiling roses????

 

[nick_r]

PS the FCU is in the airing cupboard.....for safety!

 

[plugwash]

normal practive is to have a split load CU with the lights on the non-rcd side

you say you have a rcd in your cu but whether your lights are on it is another matter

 

[ZenStalinist]

Agreed... If your sockets are one one side of the RCD, but the lights are on another, the lights will not be RCD protected. IF you want to find out if you're absolutely not sure, switch off the RCD, and see if the lights go out (obvious really...)

The manual is assuming you are installing it on a socket circuit btw, on a lighting circuit it doesn't even need to be fused, could just be connected by a double pole switch. Like I said, it's good design to use a clock connector (with an FCU, somebody may try to run a 13 amp appliance off it later), but I suppose you don't have to.

 

[ban-all-sheds]

If it's a non-RCD lighting circuit you could always use an RCD FCU, (active, or non-latching one would be best).

Biggest problem will be the capacity of the lighting circuit - a 3A pump might use up half of it...

 

[securespark]

I'm about to alienate my only fan, but I think putting the shower on the lighting just because it's a fag to lift the floor smacks of laziness. It may only be 150W (if it is - no one has said exactly what it is) but what about surge on start-up? And if the pump is not SELV then it should have rcd protection.

"On a lighting circuit it does not need an FCU?" That's fans, mate, not pumps........and the lit states it needs a 3A fuse.......

If you put the FCU on the ring, then there won't be any confusion in the future. And powershowers/pumps are not designed to go on lighting circs....

Put the pump on the ring via a 3A FCU (or whatever fuse to satisfy the manufacturer) and if it is not SELV, use a Powerbreaker H92 spur.

Then you know the job's done and if you need more oomph in the future, you know the circuit can take it, whereas if it were on the lighting, you'd be stuck.

 

[BR]

[quote="ZenStalinist] Like I said, it's good design to use a clock connector (with an FCU, somebody may try to run a 13 amp appliance off it later), but I suppose you don't have to.[/quote]

No, it is not "good design" to use a clock connector. Such an accessory is, as the name suggests for connecting clocks Full Stop

Is a dedicated circuit out of the question (i.e. a drop to the c.u)?

Have you completely exhausted the possibility of the socket ring main?

RCD protection is in my opinion critical here and therefore the lighting circuit is a difficult option. A H92 spur unit would solve the problem in theory but the circuit is becoming messy.