2 Electric Showers.. no priority unit.

Rizlablueby2

I have been asked to install a second 'mains' shower in a converted attic.

There is only 2 people living in the house and they say that they will be observant of shower use and they wont use them at the same time.

I know you can purchase a priority unit to solve this, but I have heard of an sufficient rated immersion switch being used to do a similar task. This would cost far less then the priority unit.

Something about you wiring the showers as follows.... 1st as the sink feed and the 2nd as the bath feed. And then switch between the two. Both shower cable supplies run by each other in a boxed unit in the landing, so wiring this would be handy enough.

Just wondering has any one come across this and if so is it technically alright.

Hootanany

Rocker switch is needed

tomdempsey200

you can fit a 4-pole contactor(2no/2nc) in the distribution board and control it with a 2-way switch

or even a suitably rated manual changeover switch in a suitable location

priority control with 2-pole contactor and current sensing relay is prob the handiest....


do you know what you're doing btw?..:)

2011

tomdempsey200 wrote: »

you can fit a 4-pole contactor(2no/2nc) in the distribution board and control it with a 2-way switch

or even a suitably rated manual changeover switch in a suitable location

priority control with 2-pole contactor and current sensing relay is prob the handiest....

+1 if they are instantaneous showers.
Can you confirm the size of the loads?
Either way a standard immersion switch is not the solution.

2011

Rizlablueby2 wrote: »

There is only 2 people living in the house and they say that they will be observant of shower use and they wont use them at the same time.

That is the type of statement that any electrician worth his salt would completely disregard.

Cerco

2011 wrote: »

That is the type of statement that any electrician worth his salt would completely disregard.

+1

And of course the house will be sold or leased to some poor unsuspecting person.

Bruthal

tomdempsey200 wrote: »

you can fit a 4-pole contactor(2no/2nc) in the distribution board and control it with a 2-way switch

Won't need a 2 way switch for that setup:p

tomdempsey200

ya 1 way ..

Rizlablueby2

Ya thought it was to good to be true.... just wondered had ne1 seen/heard of this way... could be handy for other wiring configurations....

Got them to pay up for the priority unit... Said it wasn't worth the chance for them, or me in skipping it...

All the same,thanks for speedy response.....,

Site is fair handy....

ptogher14

Double up. Wire them both off the same 40A RCBO.

tomdempsey200

ptogher14 wrote: »

Double up. Wire them both off the same 40A RCBO.

no...

2011

tomdempsey200 wrote: »

no...

Why not?
There may be 2 showers, but only one can be powered at a time.

tomdempsey200

2011 wrote: »

Why not?
There may be 2 showers, but only one can be powered at a time.

seriously?

it's not good or acceptable practice for a start..

i would hazard a guess it also contravenes wiring rules somewhere

tomdempsey200

if you double them up at the mcb it's 1 circuit..

circuit design current then exceeds rating of protective device...


not allowed..

2011

tomdempsey200 wrote: »

if you double them up at the mcb it's 1 circuit..

You do not need to double up at the MCB.
The MCB feeds the contactor.
The contactor feeds either one load or the other.

circuit design current then exceeds rating of protective device...

Incorrect.

The connected load is a single shower at any given time.
Therefore the design current is always less than the rating of the protective device.

By the way if you wanted an RCBO for each shower then they would have to be installed downstream of the contactor.
In this case a protective device would have to be installed upstream of the contactor (MCB or fuse) unless it was rated for 63A.

What would the adavantage of this set up be?
I can't see how it would be safer or better practice.
I can see that it requires more components (and consequently a higher chance of failure), takes up more space in the board and costs more money on materials and installation.

tomdempsey200

i think you have misinterpreted ptogher14 post

he is suggesting to use the 40a rcbo as the controller... to prevent overcurrent

2011

tomdempsey200 wrote: »

i think you have misinterpreted ptogher14 post

he is suggesting to use the 40a rcbo as the controller... to prevent overcurrent

Really?
If that is his suggestion as you say this would be against regulations and very bad practice. It is not the way I read it though.

Tokyo

tomdempsey200 wrote: »

i think you have misinterpreted ptogher14 post

he is suggesting to use the 40a rcbo as the controller... to prevent overcurrent

That's the way I read it too - wire both showers separately all the way back to the 40A RCBO. Either shower on it's own will run fine, both showers get switched on together and the RCBO trips. Sounds like a terrible idea.....

tomdempsey200

i know lads that did it

i tried it once myself before i knew better ...and she didn't trip btw

dunno what the shower ratings were at the time maybe 6-7kw or thereabouts

2011

mike_ie wrote: »

That's the way I read it too - wire both showers separately all the way back to the 40A RCBO. Either shower on it's own will run fine, both showers get switched on together and the RCBO trips. Sounds like a terrible idea.....

Perhaps I misunderstood the post.

Either way, wiring 2 instantenious showers directly to a single RCBO is not the way to go.

Tokyo

Not that I'm the biggest on following every rule in the book or anything, but don't showers now fall well outside of what's permitted for the average homeowner to wire in themselves?? OP should be getting in a sparky either way....

tomdempsey200

mike_ie wrote: »

Not that I'm the biggest on following every rule in the book or anything, but don't showers now fall well outside of what's permitted for the average homeowner to wire in themselves?? OP should be getting in a sparky either way....

OP sounds clueless unfortunately for the customer...

at least he's been persuaded to fit a proper controller

Tokyo

tomdempsey200 wrote: »

OP sounds clueless unfortunately for the customer...

at least he's been persuaded to fit a proper controller

Thats the point I'm trying to make. Not questioning anyones knowledge or anything, but at the end of the day the customer has to stand in under this thing every day and dowse himself in water - I'd be hoping it'd be done by someone who didn't have to google the answer...

tomdempsey200

plumbers and diy fit them all the time

i see miscellaneous bodges like doubling up in 1 rcbo

last one i seen was shower wired into main isolating switch before main ocpd(63amp fuse)...done by a plumber

2011

mike_ie wrote: »

don't showers now fall well outside of what's permitted for the average homeowner to wire in themselves?? OP should be getting in a sparky either way....

I agree. "Major heart surgery" on the distribution board such as this should only be carried out by an electrician, without a doubt.

Unfortunately a minority of qualified electricians will cut corners/gunter/ignore regulations. Threads such as this enable customers that have little or no electrical knowledge to understand what is compliant. They can also learn what the various options are, what is practical, cost effective, advantages/disadvantages etc. It also helps them to understand the terminology so that they can understand what the electrician is trying to explain to them.

The idea of a thread like this is not to encourage a DIYer to start poking about in a distribution board.