Electric Shower - No isolation switch and no hot water! [Moved from DIY]

eatsloads · 08-01-2009 06:55PM #1

Hi,

I got an electric shower fitted a while back and the guy didnt fit an isolation switch, he said I didnt need one? He did hook it up the the fuse board though with a separte circuit breaker. I have been told that this is against regulation? Is it safe to use?
Also, the water pressure coming in is too low so the water wont heat, the service guy said their must be somehting wrong with the water feed, ie blockage? any ideas?

Thanks

ART6 · 09-01-2009 09:08AM

I wouldn't fit an electric shower without an isolation switch (ceiling fitting and pull cord in the bathroom near the shower) and an RCD (residual current device) in the main switchbox. The RCD (or RCBO) will keep you from getting elctrocuted if there's a fault with the shower.

On the low pressure problem, what make of shower is it? If it's mains supplied as i would assume it is, check that the mains water valve is fully open and that the filter inside the shower case is clean. If it's fed from a roof tank, try disconnecting the water pipe and see if that flushes anything out.

eatsloads · 09-01-2009 10:11AM

There is a 30mA RCBO on the fuse board.....what exactly is the purpose for an additional isolation switch?

The shower is fed from a water tank above it in the attic.....the pipe and the filter look ok.....

northdublin · 09-01-2009 06:27PM

i had the same situation recently in a house where the home owner fitted the wrong shower, the shower was fed from a tank in the attic but it wasnt a pumped type electric shower and feed from the tank didnt have near enough pressure to opperate it propperly. we then fed it directly off the mains and this sorted the problem. also sometimes the mains supply can be too powerfull and a reducing valve needs to be fitted.
the rcbo is there to protect the person using the shower incase if becomes faulty.the rcbo will trip instantly if a fault occurs. the idea of the 45amp switch is to be able to isolate the shower from the mains if a fault occurs or to service it

GreeBo · 09-01-2009 06:32PM

eatsloads wrote: »

Also, the water pressure coming in is too low so the water wont heat, the service guy said their must be somehting wrong with the water feed, ie blockage?

Was the water pressure ever any better?
If the shower fixture is just supposed to heat the water with no pump and you are using gravity then you get the scalding hot dribble we all know and love.
Can you hear a pump running when the water is running?

I cant see why pressure would affect the temperature though... Unless it cuts itself off due to low flow...

ART6 · 09-01-2009 06:59PM

eatsloads wrote: »

There is a 30mA RCBO on the fuse board.....what exactly is the purpose for an additional isolation switch?

The shower is fed from a water tank above it in the attic.....the pipe and the filter look ok.....

A single RCBO can protect all of the circuits in the house, but that means that if any one of those develops a fault you lose all power everywhere. A dedicated RCBO for the shower ensures that it trips without shutting everything else down.

The shower should have an isolating MCB at the switchboard and a cord switch in the bathroom. The purpose of the MCB is to isolate the shower system including the bathroom switch.

Many (most?) electric showers require mains pressure to work, so you need to check with the maker's web site for yours to see if it's a mains type or a gravity. They all work by regulating the flow of cold water through the heater to achieve the temperature you want -- less flow, higher temperature--so if you can't get the temperature you don't have sufficient flow.

edward543350 · 10-01-2009 12:25AM

what make is the shower?

eatsloads · 12-01-2009 02:55PM

Thanks for the info!

Shower is Dimplex Powerscourt 10.5KW, hard to find info on it.........

ART6 · 12-01-2009 06:14PM

I think those are pumped units (have their own pump). If it's being supplied from a tank then you might have a blockage or restriction in the pipework to it, or the filter in the shower control box could be dirty. Also worth taking off the shower head and its flexible pipe and then try the shower. If you get a full flow of hot water, then the rubber sleeve inside the flex has collapsed (that happens!).

Stoner · 13-01-2009 12:44PM

just a quick thing, there is a difference between an RCD and an RCBO. typically an RCD provides additional leakage protection for a number of circuits, each of these circuits have their own MCB. That's why when they trip (due to an iron for example) all the sockets in the house trip, even though there are three or four circuits, the RCD sits on top of them all and will kill power to all MCBs / other circuits it feeds.

An RCBO is a combined RCD and MCB, it acts alone, it only controls one circuit so when it trips only one circuit goes down, i.e a shower tripping will not kill sockets and a broken kettle wont trip the shower.

For most typical power showers like Triton T90 and the Mira elite range a 10sq cable and 40 Amp RCBO is required.

An additional Isolation switch, local to the shower is also required to allow someone to isolate the unit to work on it safely, and to provide a quick and obvious mean s to kill power to the unit.

Under no circumstances should an electric shower be installed without a double pole isolator as part of the circuit.

also sometimes with electric showers there is not enough water head i.e the water tank is too near to the shower, the greater the distance between the tank and a pump shower the better, this creates a semi constant amount of water with a bit of pressure behind it, 1 M is about the minimum I think.

fishdog · 13-01-2009 12:51PM

Also, the water pressure coming in is too low so the water wont heat, the service guy said their must be somehting wrong with the water feed, ie blockage? any ideas?

The shower should have its own dedicated 1/2" pipe supplying it. This should come from the tank in the attic, with at least 6' for head (so I was told). To test if the pipe is blocked, simply turn off the power to the shower, take off the cover and open the bleed screw, this will also remove airlocks which may also be your problem. If you get a nice staedy stream of water you have no blockages.

Unless it cuts itself off due to low flow...

It does, there is a pressure switch.

Electric Shower - No isolation switch and no hot water! [Moved from DIY]

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