Fitting RCBO for 9.5 KW shower, my idea, (with pic)

dohouch

Want to fit this myself, but for obvious reasons am checking it once, and checking it twice.

Shower is 9.5KW, pass through heater, (no pump) direct of the mains. Cable length from C.U. to shower is about 12 feet. Have got my 6mm cable and plan on getting a 40A RCBO and pull-cord 3 pole switch for inside bathroom.

the picture below is my idea for connecting the RCBO, will it work or is it frying time again?

Thanks

grousedogtom

Dont connect live to bottom of main switch fuse, as this connection wont isolate shower if taken from bottom , take from top instead, also 9.5 kw is heavy load might require 10 sq cable.A 45 amp double pole shower switch would be suitable.

M cebee

Get an electrian:mad:

dohouch

Of course, @grousedogtom, connect to the Output of Main fuse. But the other connections are O.K.ish, then. Here is a pic of the ratings table from shower installation booklet. The distance to shower from CU is just 4 meters.

bassey

dohouch wrote: »

pull-cord 3 pole switch for inside bathroom.

Thanks

:eek:

dohouch

@M cebee: Might do that anyway or as well.

dohouch

bassey wrote: »

:eek:

What's up? A pull-cord switch that has Live and Neg and Earth passing though it. Is that wrong?

bassey

Does it break the earth when it's switched off?

2011

If I were installing this:
1) I would use a 10 sq. T + E for a 9.5kW instantaneous shower
2) I would install a larger distribution board
3) Carry out earth fault loop impedance & insulation test on the new circuit
4) If using the same board, move the bell traffo out of the board and replace with a surface mounted type. This can be mounted beside the board.
5) Use an MK DP isolation switch (rated at 45A per pole). Unlike most of the others it will last.
6) Check EVERY connection in the board is tight
7) Replace the busbar so that there are no connections
8) Ensure all connections are very good. No strands cut out etc...
9) I do not see a 10 sq. earth cable for your earth rod. Check this out!

No offense, but by the type of questions you are asking I think it would be best to get an electrician to do it. I can see you have a good grasp, I but don't think you should take the chance!

Why is there a 20A not protected by the RCD??

dohouch

bassey wrote: »

Does it break the earth when it's switched off?

Thanks for coming back on that.

Haven't bought the RCBO or pull-cord yet. Was in an electrical supplier a few weeks back and this is only my memory of what they were suggesting.
Will learn more when I go buy. Just checked the diagram in "shower installation booklet, and see the pull-cord has an Earth connection back to Shower but NOT running through it,

dohouch

@ 2011: Thanks for the input. I wanted to learn a bit, but you're breaking my b.lls here, but I do appreciate you post and
am maybe hearing more than I was ready for.

2011 If I were installing this:
1) I would use a 10 sq. T + E for a 9.5kW instantaneous shower
Me: There is a pic here of the wiring and fuse ratings, you think 6 sq is marginal?

2) I would install a larger distribution board
Me: Not going to happen.

3) Carry out earth fault loop impedance & insulation test on the new circuit
Me : Still don't know which local sparks to get.


4) If using the same board, move the bell traffo out of the board and replace with a surface mounted type. This can be mounted beside the board.
Me: Good idea,

5) Use an MK DP isolation switch (rated at 45A per pole). Unlike most of the others it will last.
Me: Old English brand MK, right,

6) Check EVERY connection in the board is tight

7) Replace the busbar so that there are no connections
Me: Don't understand

8) Ensure all connections are very good. No strands cut out etc...

9) I do not see a 10 sq. earth cable for your earth rod. Check this out!



Why is there a 20A not protected by the RCD??
Me : I'm the 2nd person to live in this 10 year old house (council), I think this is the original set-up, so as installed by builder and etc.

cbrlover

The first thing I would say is, if I was you I would get an electrician.

Having said that if you insist on proceeding with the job yourself the one thing I would recommend is forget about any brand 45A pull cord and get a 50A, with this shower being 9.5Kw.

I know there are other brands but I would use an MEM Eaton one and you can’t go wrong. I have seen loads of 45A switches burnt out on 9.5Kw showers including MK. It is not the switch that is the problem but the irregular electrical supply in Ireland can take load over 45A.

Just my bit.

The last thing I would say is, if I was you I would get an electrician.

dohouch

cbrlover wrote: »

The last thing I would say is, if I was you I would get an electrician.

Thanks for your time.
I would like to do as much as I can myself, try and get it right, then find a sparks or 2 for 2nd opinions. Don't mind throwing a few bob their way but I'm idle at the moment and........


Boards member "2011" says 45A MK, you say 50A MEM Eaton, can see that a 50A switch will give a margin which would probably give a longer trouble free life.
rgds

Bruthal

2011 wrote: »

Why is there a 20A not protected by the RCD??

It seems to be a 20A MCB used for the cooker circuit.

Bruthal

grousedogtom wrote: »

Dont connect live to bottom of main switch fuse, as this connection wont isolate shower if taken from bottom , take from top instead.

Take it from the bottom of one of the MCBs with no cable into its clamp, to the left of the main switch is better. The top of them main switch fuses would not be great for a second large cable to be connected in.

This is a job where an electrician should certainly be doing it. Amateur connections always are just that, even though it seems simple, and there is more to it than just the connections here.


Also OP, there would be no earth connection to the double pole RCBOs.

dohouch

robbie7730 wrote: »

It seems to be a 20A MCB used for the cooker circuit.

That's right.. Have a gas cooker though ( with gas bottle in kitchen, Oh oh :eek:)) , so I use this for an extra socket.

Bruthal

dohouch wrote: »

That's right.. Have a gas cooker though ( with gas bottle in kitchen, Oh oh :eek:)) , so I use this for an extra socket.

If it has a socket on it, it needs to be connected through the RCD on that board, older houses had a socket on the cooker switch years ago, but they are gone now bacause cookers are not on an RCD so the socket on the cooker switch would not be covered by the RCD.

Although i still see them cooker switch/socket units on sale in woodies etc.

dohouch

Thanks.

robbie7730 wrote:

Take it from the bottom of one of the MCBs with no cable into its clamp, to the left of the main switch is better. The top of them main switch fuses would not be great for a second large cable to be connected in.

Agreed, makes sense

robbie7730 wrote:

This is a job where an electrician should certainly be doing it. Amateur connections always are just that, even though it seems simple, and there is more to it than just the connections here.

After a month or so of this thread, I will be the Boards specialist on this. Will start looking for a local sparks that will come some of the way with me on this.

robbie7730 wrote:

Also OP, there would be no earth connection to the double pole RCBOs.

Blame Wikipedia, but can't find the link now. Thought these RCBO's came with flying Earth lead. Haven't bought yet.

Bruthal

dohouch wrote: »

Blame Wikipedia, but can't find the link now. Thought these RCBO's came with flying Earth lead. Haven't bought yet.

That type is probably a solid neutral single pole RCBO with an earth fly lead. The type you will probably get here is a double pole one with no earth fly lead on it.

2011

cbrlover wrote: »

Having said that if you insist on proceeding with the job yourself the one thing I would recommend is forget about any brand 45A pull cord and get a 50A, with this shower being 9.5Kw.

40A RCBO supplying a 45A isolator. I see no issue.
I have done this many times and never had a problem.
Personally I never switch them off, I dont see the point.

Having said that, there is nothing wrong with a 50A.

I would suggest to use it under no load conditions.

M cebee

maybe it's a 8.5/9.5kw 230/240v model

that would be approx 37amp


a 230v 9.5 would be over 41amp

cheap pull-cords are a nightmare - i like the crabtree anyhow

10sq t+e works well with it

dohouch

2011 wrote: »

40A RCBO supplying a 45A isolator. I see no issue.
I have done this many times and never had a problem.
Personally I never switch them off, I dont see the point.

Having said that, there is nothing wrong with a 50A.

I would suggest to use it under no load conditions.

Can't see myself using the pull cord to often either and really putting it in to
keep to standards.

2011

M cebee wrote: »

maybe it's a 8.5/9.5kw 230/240v model

that would be approx 37amp


a 230v 9.5 would be over 41amp

cheap pull-cords are a nightmare - i like the crabtree anyhow

10sq t+e works well with it

I have not used Crabtree in over 20 years. I have heard good things about them though. MK is always high quality and will take 10 sq. cable no problem.

If this was a new installation I would not go for a pull cord, a wall mounted isolation switch is a far better job. However the adavntage with the pull cord switch is that is saves chasing a wall.

dohouch

@M cebee. Think you hit on something there.

M cebee wrote: »

maybe it's a 8.5/9.5kw 230/240v model

that would be approx 37amp


a 230v 9.5 would be over 41amp

cheap pull-cords are a nightmare - i like the crabtree anyhow
10sq t+e works well with it

On cardboard box: Creda, Short Code 950 DL, Watt: 9500-8725
On Sticker inside unit: Watts: 8725-9500 Volts:230-240
Sticker On Heater itself: 9500W 240V
7983W 220V

In post 3 of this thread, is pic, with suggested cable fuse, etc. My distance is less than 15 ft CU to Shower. I've bought the 6 sq cable, but at least 2 have said must 10 sq. Can all be done of course, but that's really phat.
rgds

2011

dohouch wrote: »

Can't see myself using the pull cord to often either and really putting it in to
keep to standards.

Exactly.

Also but a good solid wooden base in for the pull cord or you may damage the ceiling, such as an A4 sized piece of plywood with a hole in the middle.

TheBody

No offence intended op but I've a bad feeling about this job. Every sparks posting here knows that this really isn't a job for an amateur. I appreciate you want to do this yourself but the potential for electric shock/fire/death etc is huge here. This is not like plumbing where you might get a wet foot!!

dohouch

TheBody wrote: »

No offence intended op but I've a bad feeling about this job. Every sparks posting here knows that this really isn't a job for an amateur.

@TheBody: No offence taken and I certainly wouldn't offer to do this for somebody else. I can hang the shower, already done. I can do the pipe work. Missing a junction or might be finished already and be here with moist feet, might even get Trench Foot over time.

If we could reach agreement on cable size I could run cable from Shower to pull-cord, pull-cord to CU, and then put my sticky fat fingers into my wallet and bring in a willing sparks, show him/her a diagram of my runs and let him/her finish it, or finish it myself and have her/him check it by taking the first shower.

M cebee

dohouch wrote: »

@M cebee. Think you hit on something there.



On cardboard box: Creda, Short Code 950 DL, Watt: 9500-8725
On Sticker inside unit: Watts: 8725-9500 Volts:230-240
Sticker On Heater itself: 9500W 240V
7983W 220V

In post 3 of this thread, is pic, with suggested cable fuse, etc. My distance is less than 15 ft CU to Shower. I've bought the 6 sq cable, but at least 2 have said must 10 sq. Can all be done of course, but that's really phat.
rgds

nothing remarkable there-fairly standard labelling with showers 230/240

that's why you should get an electrician

that knows what he's doing

2011

M cebee wrote: »

that's why you should get an electrician

that knows what he's doing

+1

This is a lethal voltage you are dealing with after all.

dohouch, you don't have the experience, training or test equipment. In addition many of your questions "worry" many of us. None of us would like to see you or anyone else get hurt. From the information you have received in this thread you should be able to ensure that a registered electrician does exactly what he should and have a better understanding of what is involved.

I wish you the best of luck with it!

M cebee

8, 8.7 and 9.5. would be tbe wattage of tank at 220,230 and 240 alright

although im sure ive seen them marked 8.5/9.5

Stoner

to be honest 10sq is recommended so you should go with that, it's only 6sq in my place but I'd rather 10sq, it's not going to cost you that much more and the way shower loadings are going you'll need more and not less current carrying capacity in the future, so do it now and save later IMO.

So 10.sq.mm cable. Your isolator will also be fine at 45Amp IMHO. So long as it is a switch mounted outside the shower room and within the correct distance from the shower 1.5M I think, open to correction please. If it's a council house like mine that should not be a problem asthe bathroom is on 1.5 x 1.5M anyway:)

All in all I agree that it's a great idea for you to run the cable and hang the shower, while leaving the connections to a qualified person, this will give you the max cost saving and keep things safe.

what route do you plan to use for the cable?

dohouch

@Stoner: Small point I know but I already have the 6 sq. cable, but will consider it, no work happening for a day or 2.

Was going to mount isolating switch inside shower-room, thought that was the reg, and as it is pull-cord safe enough. To mount outside room is cable length of 2 Mtr (8 ft.) and really, really about 6 inches from RCBO. and CU. House is single person house, 1 bedroom.

Stoner:what route do you plan to use for the cable?

Don't know what you mean. The shortest I suppose, in the attic lying on top the "wolly" insulation. This under the lowest part of the roof, almost over the inner side of the cavity wall. As I said earlier in thread, distance from CU to shower is about 12 ft.

Solair

OP: I do not mean to be offensive, and I am only saying this to prevent death, injury or financial loss but :

Just one word of warning, if you do serious electrical work in your house and it is not in compliance with ET101 (current edition), you can find if the installation causes a fire, your insurer might tell you to get lost if you claim. They are starting to get a lot meaner about paying out.

Modifying a socket or putting in a light is one thing, but installing a shower actually requires considerable training and test equipment.

If there are any earthing problems or you get something slightly wrong, you are potentially exposing yourself and anyone else using that shower to almost certainly lethal electric shocks delivered in their bare feet on a wet surface.

This is not a suitable job for DIY.

Also, that consumer unit is sloppily wired and quite cramped. I don't really see where you are going to put the RCBO. You realise they're quite large, and that 10mm2 cable doesn't bend very easily, right?

dohouch

@Solair:

Also, that consumer unit is sloppily wired and quite cramped.

I'm not in the building or related business here locally , so quite possible to end with the same sparks or of similar working methods/standards as the one that installed fuse box (this fuse box is to the best of my knowledge the original)

Asked the only local sparks I know(doesn't do it any more) about carrying out earth fault loop impedance & insulation test on the new circuit. His idea was the sparks around here don't carry that level of equipment.

Will look for some more feedback on local sparks.

M cebee

any electrician doing installation work should have that equipment


whether he's registered or not