Shower question

[alfiembra]

I have a gainsborough electric shower with three power settings, low, medium and high. It works fine on low and medium, even to the point of being more than hot enough on medium, but if I try it on high power it trips the circuit breaker. I'm a DIY'er so not a qualified electrician. AFAIK the cable is big enough for the unit but was wondering if it could be the water supply not being strong enough as at medium power it isn't a very strong flow but sufficiently hot.

Thanks

Alan

 

[kkynaston]

IMO low water pressure should not trip an MCB as the shower would shut itself down.
When you put the shower on the high setting it will draw more current.

What is the rating of the shower breaker and the size of the cable from the breaker to the shower?

 

[Steve]

How an electric shower works:

LOW = no heat or one heater element, typically 3kw.
MEDIUM = one heater element, typically 6kw.
HIGH = two heater elements, typically 3 and 6kw, total 9.

Do a little experiment for me. Turn your shower on low power. Now, turn the temperature (not power) dial from red to blue or 10 to 1, right round. Notice what happens. It varies the pressure. This is its job. This dial simply increases or decreases the water flow. This works because on low pressure, the water spends more time in the heater, and therefore becomes hotter. Conversely, on high pressure, it goes through the heater quicker, and therefore doesn't gain as much temperature.

 

[alfiembra]

What is the rating of the shower breaker and the size of the cable from the breaker to the shower?

Will check tonight and get back to you

Bit more info on the shower

Gainsborough Energy 2000

extract from a spare parts list for the model

HEAT EXCHANGER 10 . 8KW
HEAT EXCHANGER 9 . 5KW
PRESSURE RELIEF DEVICE 9 . 5KW
SWITCH PRESSURE SELECTOR 9 . 5KW
WIRE SET 9 . 5KW/10 . 8KW

HTH

Alan

 

[Steve]

So you either have a 9.5 or 10.8kw shower. But it still works the same as I said above. They all do.

9500 watts is 41.3 amps. This will trip a 32 amp MCB in a couple of hours, but wont trip a 40 amp MCB.

10800 watts is 47 amps. This will trip a 32 amp MCB almost instantly, and trip a 40 amp in an hour or so.

My money's on a 10.8kw shower on a 32 amp MCB.

 

[alfiembra]

Top of the class Steve, the circuit breaker is marked with 30 on the switch I'm assuming that means it's 30 Amps, been in touch with an electrician to check out the whole flat so another job to add to the list.

Thanks everyone for your help.

Alan

 

[ban-all-sheds]

But it still works the same as I said above. They all do.

Mine doesn't.

 

[plugwash]

How an electric shower works:

LOW = no heat or one heater element, typically 3kw.
MEDIUM = one heater element, typically 6kw.
HIGH = two heater elements, typically 3 and 6kw, total 9.

Do a little experiment for me. Turn your shower on low power. Now, turn the temperature (not power) dial from red to blue or 10 to 1, right round. Notice what happens. It varies the pressure. This is its job. This dial simply increases or decreases the water flow. This works because on low pressure, the water spends more time in the heater, and therefore becomes hotter. Conversely, on high pressure, it goes through the heater quicker, and therefore doesn't gain as much temperature.

I'm sure thats how the cheap and nasty ones work but i'm also sure you can get thermostatic ones.

 

[securespark]

But it still works the same as I said above. They all do.

Mine doesn't.

To be fair to Steve, that's how electric showers with switchable elements work, give or take.

But if your electric shower has no switches, only a water flow adjuster, then the power drawn is the same all the time and the temperature adjustment is made by altering the speed of water flow through the can.

 

[Softus]

But it still works the same as I said above. They all do.

Mine doesn't.

Of course it does.

 

[plsdntlaugh]

Hello All,
This is my first post and already I've hijacked someone else's thread - hope that's okay.
To keep it brief -
we recently bought a 10.8kW Mira Sport Max shower thinking we would soon have a wonderful shower. My electrician has since explained slightly more about how these things work BUT he seems to think that the highest 'trip' he can get for our consumer unit is a 30A thus meaning that our sooperdooper shower has to go back to the shop and we have to get a 7kW one.
So I suppose my question is; does the make of a consumer unit dictate the size (A) of 'trip' that can be bought for it? IYKWIM?
Thanks for reading.
Daisy

 

[ban-all-sheds]

The make doesn't, but the age does - either yours is so old that MCBs are hard to find, or so old that it was never made with the expectation that people would ever have a load greater than 7kW.

You could post the details of it here, or a photo, for confirmation, but I expect that's the situation you are in.

There are two alternatives to returning the shower. One option is to completely replace the CU, and your electrician might well have shied away from suggesting that, as it could work out costly, but I am surprised he didn't suggest the other option of installing a separate mini-CU for the shower.

On balance, if your existing CU is so old that it won't take a high load appliance, it could be that your entire installation needs work doing - ask your electrician about it, get him to do an inspection....

 

[plsdntlaugh]

Thanks for your speedy response.
The CU doesn't look so old but the house is. We only bought it a couple of years ago. The CU is a Square D - not sure if this is the model number but it has BS 5486 Pt 13/12 on the front of it.
I suppose it is also relevant to tell you that the 'head' coming into the house has 60/80A on it.
I'll take a photo of the CU. just in case that helps.

 

[plsdntlaugh]

OK here's a photo of the CU -scuse the dust!

 

[seco services]

you've gone through all that and not even checked if one of your heating elements is faulty and tripping on high power.