Substituting shower pull cord for wall mounted switch-help!

Hi guys, my 1st time here - so go easy on me!

I have a small question regards wiring for shower.

I currently have a 7.5kw electric shower, with a pull cord switch inside the bathroom. I want to remove this switch, and replace it with a wall mounted version on the exterior wall of the bathroom.

As far as I can see, what I need to do is install a junction box in the loft space (I have obtained a box, with a 60amp connector strip), remove the wiring from the existing pull switch, enter it in to the strip through the box. Then run new cabling (I have purchased some heavy looking cable that claims to be for cookers and showers, and looks the same gauge as that which is already there). I propose to run this new cabling down through the void between a plasterboard wall, into a new 45amp neon wall switch, and back up to the box in the loft, thus completing the circuit. In essence, all I will have done is extend the wiring and change the switch.

I have done a similar operation when I removed a pull cord light switch, and fitted a regular wall mount light switch. I expect it to be much the same with this shower switch, but I am slightly apprehensive, given the heavier nature of the components I propose to involve.

My question is "Does this all sound ok, or can anyone see any problems with what I am planning?"

I welcome any feed back. It may seem a trivial matter, but I want to make sure it's right!

Thanks to anyone who reads this!

Best to have no joints whatsoever. You need to be familiar with cable size to do the next bit: if you are upgrading the shower, you need to think about whether the existing components comprising your circuit are up to scratch: the CU, RCD, MCB, Cable, Switch (know you are changing this anyway)etc...

Depending on the size of shower you want to fit (or may want to fit in the future), you may need 50A mcb and rcd, 10mm cable and a 50A switch.

You also need to make sure bonding is up to the job.

If your meter and fuse are very old, you may need your supply upgrading to 100A, but you need to contact your supplier about this.

where is the switch going to be ?

breezer said:

where is the switch going to be ?

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gairloch said:

a wall mounted version on the exterior wall of the bathroom.

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(I assume he means on the other side of an internal bathroom wall, not on the outside of the house..... )

Gairloch - a few points.

1) Would someone inside the bathroom be able to determine the position of the switch? If not, you have complications regarding concealed cables to deal with.

2) Agree with all that's been said about joints. I would have thought it should be easy to avoid at least 1 - the existing cable that runs up to the ceiling, could this be re-routed to go directly to the switch?

3) Also, definitely equip yourself for a 11kW-ish world, even if you aren't replacing the shower now. 10mm² cable and a 50A switch (Crabtree make one)

Hey guys, I appreciate your posts, here's some further information...

I have further investigated the shower and it is in fact a 8.5kw, not a 7.5kw.

I have found the cable that leads to the exisiting pull cord switch from the fusebox, and yes it will be possible to re-route that down through the plasterboard wall to the wall switch without to a problem. I also reckon that I will be able to insert new cable into the shower itself and route this also, to the switch. This would cancel out any problems arising with joining cables at junction boxes etc.

Also, sorry for confusion, but the switch would be mounted on the wall, at shoulder height, adjacent to the bathroom door, but on the outside of the room, i.e. in my hallway.

As for cable, I hear what you are saying about 10mm2 cable, and I will make sure I use that for the new cable from switch to shower. The existing cable, from switch to fusebox, is huge. Frankly I am unsure of how to measure this to see if it is 10mm2, but I guess that when I buy the new 10mm2 cable, as long as it matches that which exists, then I should be ok?

This existing cable runs, as I said, from the switch along the roof joists, down toward the fuse box, in which is a 40amp trip switch, which plugs in, like a regular fuse would. Given that this switch has been working for, presumably years, would this be ok to be left? Or should It be replaced with one at, say, 50amp? I cannot see any other protective devices, if indeed there should be more.

I must again, say sorry, for not using technical terms, but I hope you all understand what I mean.

This brings me to my penultimate question, try as I might, scouring the web, and browsing my CEF (City Electrical Factor) brochure, I cannot find a 50amp DP switch, largest I can get is 45amp. Can anyone give me a link to a site, where I may be able to order a 50amp switch in a brass finish (to blend in with my existing switches)?

Lastly, are there any problems with cable routing? I.e. Presumably I should keep the cable above the loft insulation, and clip it in place as often as possible? Would I need to protect the cables to and from the new wall switch, which will be inside the void in the plasterboard wall, from ceiling to shoulder height, with any kind of conduit, or is that not neccesary, as the location of the switches themselves would "give away" the location of the cables?

Apologies for the long post guys, but I do appreciate your thoughts, and hope you can find the time to add some more words of wisdom!

gairloch said:

I have found the cable that leads to the exisiting pull cord switch from the fusebox, and yes it will be possible to re-route that down through the plasterboard wall to the wall switch without to a problem. I also reckon that I will be able to insert new cable into the shower itself and route this also, to the switch. This would cancel out any problems arising with joining cables at junction boxes etc.

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Excellent

As for cable, I hear what you are saying about 10mm2 cable, and I will make sure I use that for the new cable from switch to shower. The existing cable, from switch to fusebox, is huge. Frankly I am unsure of how to measure this to see if it is 10mm2, but I guess that when I buy the new 10mm2 cable, as long as it matches that which exists, then I should be ok?

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Yup. If you own a pair of vernier callipers you can measure the size of one of the conductors, to see if its area is 10mm². TLC's website has overall dimensions of cables - 10mm² is about 17mm x 10mm

This existing cable runs, as I said, from the switch along the roof joists, down toward the fuse box, in which is a 40amp trip switch, which plugs in, like a regular fuse would. Given that this switch has been working for, presumably years, would this be ok to be left? Or should It be replaced with one at, say, 50amp? I cannot see any other protective devices, if indeed there should be more.

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40A will be fine for an 8.5kW shower - you can replace it as and when you replace the shower. The only niggling worries I have are that as this is an old fusebox with plug-in MCBs, what is the rating of the main switch, and does the shower have RCD protection?

This brings me to my penultimate question, try as I might, scouring the web, and browsing my CEF (City Electrical Factor) brochure, I cannot find a 50amp DP switch, largest I can get is 45amp. Can anyone give me a link to a site, where I may be able to order a 50amp switch in a brass finish (to blend in with my existing switches)?

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Crabtree are the only makers I know of, but there might be others. Go here http://www.electrium.co.uk/download_file.asp?Type=C&Company=3&Id=11 and download the catalogue - see the bottom of p41. It's only available in plain brass though - not "Georgian" or "Victorian" (as if the Georgians had electricity.... ), but it might be close enough. Alternatively use a 45A one, and stick to 10.3 - 10.8kW showers...

Lastly, are there any problems with cable routing? I.e. Presumably I should keep the cable above the loft insulation, and clip it in place as often as possible? Would I need to protect the cables to and from the new wall switch, which will be inside the void in the plasterboard wall, from ceiling to shoulder height, with any kind of conduit, or is that not neccesary, as the location of the switches themselves would "give away" the location of the cables?

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I need to dash - if nobody else points you at the info on concealed cable zones I'll edit this later.

All good news, thanks for that!

Your 2 concerns, however, how do I know/where do I find out, what the rating of the main switch is?

Secondly, you mention an RCD, and after browsing an online user manual for Mira Zest shower, it is clear that a 30mA RCD should be fitted. Should it look like this? //www.diynot.com/shop/4_POLE_63A_30MA_RCD/4004 If so, then, I can find no sign of it! How do I go about fitting one?

Also, sorry to take up so much of your time, but I'd like to hear your thoughts on the cable concealment/routing issue.

Thanks again for your time!

/me hands ban-all-sheds an imaginary tenner!

gairloch said:

All good news, thanks for that!

Your 2 concerns, however, how do I know/where do I find out, what the rating of the main switch is?

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It should say, somewhere on the CU, what it is

Secondly, you mention an RCD, and after browsing an online user manual for Mira Zest shower, it is clear that a 30mA RCD should be fitted. Should it look like this? //www.diynot.com/shop/4_POLE_63A_30MA_RCD/4004 If so, then, I can find no sign of it! How do I go about fitting one?

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That's a 4-pole one, so it's twice as wide as one you'd have, if you had one. Easy way to spot - they all have a test button. Sounds like you don't have one. You could add a standalone RCD mounted in a small enclosure just after where the cable leaves the CU, or you could install a small dedicated shower CU with RCD & MCB, and not have the shower come off your fusebox. However unless you have an isolation switch before the CU to allow you to completely cut off the incoming supply, the latter would require you to remove the service fuse, which is not something that a DIY-er should be advised to do

Also, sorry to take up so much of your time, but I'd like to hear your thoughts on the cable concealment/routing issue.

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It's going to hinge on whether someone in the bathroom would be able to determine where the switch is. See:

http://www.niceic.org.uk/approved/quest3.html

http://www.niceic.org.uk/downloads/concealedcables.pdf

http://www.iee.org/Publish/WireRegs/IEE_Thin_walls.pdf

Thanks for being patient m8, but I feel that this is slipping away from me...

I cannot see any thing on the CU that looks like it may be a main switch rating, that said, I cant see anything that looks like a main switch, except the huge on/off switch that sits on the fusebox. All that I have on the board is the fusebox with 5 fuses including the trip switch for the shower, and the meter itself which says its 20-100a. I feel somewhat confused now, and slightly thick!

Also, what would happen if I didnt fit this RCD? I mean, if I never had one before, will it matter much? Or did whoever fitted the shower, just cut corners?

I appreciate your efforts to keep me and mine safe though, but I'm almost at the stage where I'm gonna say "Sod it, the pull cord switch ain't that bad!". Almost, but not quite!

Also I saw the sites you mentioned about hidden cabling. The main point would be that would anyone in the room, on the other side of the wall from the wall switch, be able to tell where the wall switch was-presumably so he didnt whack a huge nail in, to hang a picture or something? Given that the room on the other side of the switch is the bathroom anyway, and that the switch would be about 30 cm along from the door aperture, so unlikely that someone would choose to hane a picture or mirror there, do I have a problem with this?

As always, I value your advice.

gairloch said:

Thanks for being patient m8, but I feel that this is slipping away from me...

I cannot see any thing on the CU that looks like it may be a main switch rating, that said, I cant see anything that looks like a main switch, except the huge on/off switch that sits on the fusebox. All that I have on the board is the fusebox with 5 fuses including the trip switch for the shower, and the meter itself which says its 20-100a. I feel somewhat confused now, and slightly thick!

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Can you post a photo?

Also, what would happen if I didnt fit this RCD? I mean, if I never had one before, will it matter much? Or did whoever fitted the shower, just cut corners?

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Well - RCDs are advisable. Past performance is no guide to the future. The value of your safety may go down as well as up, and all that. I could have spent my whole time driving so far without a seat belt, and I'd not have come to any harm, but tomorrow when I get in the car I'll buckle up.

A standalone RCD fitted after the CU is easy to install - if you were happy to replace cables and switches then it's no harder than that.

I appreciate your efforts to keep me and mine safe though, but I'm almost at the stage where I'm gonna say "Sod it, the pull cord switch ain't that bad!". Almost, but not quite!

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It's not because you're changing the switch that an RCD is advised...

Also I saw the sites you mentioned about hidden cabling. The main point would be that would anyone in the room, on the other side of the wall from the wall switch, be able to tell where the wall switch was-presumably so he didnt whack a huge nail in, to hang a picture or something?

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Yup.

Given that the room on the other side of the switch is the bathroom anyway, and that the switch would be about 30 cm along from the door aperture, so unlikely that someone would choose to hane a picture or mirror there, do I have a problem with this?

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No - 30cm from the doorway is definitely close enough for someone in the bathroom to be able to tell it's there.

Ok m8,

So I'm ok with the cabling and I should be able to fit an RCD, so the only concern I have left is my main switch rating, which I haven't a clue about!

As requested, here are 2 pictures of my fusebox etc, for your comments, see if you can figure it out?




As always, thanks for your help!

does the base for that B40 breaker seem to be sitting straight?

if not then it is most likely that it has been formced into a model of CU which is unsuitable

It plugs in fine m8, doesnt seem to sit at an angle, and sits flush without forcing it home. I presume it's ok?

Isn't the breaker at the wrong end of the box? The breaker should ideally be next to the incomer.

Interesting black marks below too.

Sorry, gairloch - I should have warned you that when you post a photo of your CU area, people immediately start spotting oddities.

I'd wondered about those burnmarks too, but b-n got there first, so I'll go for "is that main earth cable 16mm²?"