interestrateripoff Posted January 10, 2011 Share Posted January 10, 2011 http://www.google.co.uk/#q=redring+super+7s+kw&hl=en&prmd=ivns&ei=50QrTcTDJo-1hAezm9TtAQ&start=10&sa=N&fp=de610b7113b09eab We need to replace our old shower unit, but the shop is asking about kW rating and I've got no idea. http://www.shower-spares.co.uk/redring_showers.html Super 7 (80-85) | Super 7 (92-95) | Super 7S | Super 7XSuper Extra 7.2kW | Super 8 | Super Extra 8.5kW To me this seems to suggest it's a 7.2kW? Can we replace this with a 8.5kW? The cable coming from the fuse box is similar gauge to what's connecting the cooker, I presume this is all the way up to the switch at the top of the stairs, although I've no idea what the cable is like from the shower switch to the actual shower. Repair diagram Anyone got any ideas on this? Thanks. Link to comment Share on other sites More sharing options...
Harry Monk Posted January 10, 2011 Share Posted January 10, 2011 Domestic electric shower units are normally rated at between 7-10kW. You need to measure the diameter of the cable that feeds it (the copper core, not including the insulation). A 4mm cable is rated to 7.75 kW, the next size up is 6mm which is rated to 9.75kW. Link to comment Share on other sites More sharing options...
Number79 Posted January 10, 2011 Share Posted January 10, 2011 You really need to know the cable size. If it is 4mm then no is the answer. Fortunately there are few cookers put in on 4mm so if the cable is the same as the cooker cable then there is every chance that it is 6mm in which case it is fine. The safest place to look at the cable is probably inside the shower. ISOLATE the shower at the fuse box by switching the circuit breaker off. Make sure that the shower circuit is dead. Whip the front off the shower and look at the cable, take it out if need be and find out if it is 4mm or 6mm. Link to comment Share on other sites More sharing options...
geezer466 Posted January 10, 2011 Share Posted January 10, 2011 If you are into all that Hip Pak stuff (before they binned the idea) and electrical safety then the simple fact you are replacing the shower means you are duty bound to uprate the cable. If like me you are not then don't worry about it. Don't be tempted to fit a higher KW shower if you are in any way unsure about the cable. If it is rated to low then it will get hot possibly very hot and could combust all sorts of materials like old fag packets and insulation material that you have lurking under your floorboards. At the same time you not be naughty by checking the fuse rating in the consumer unit. Edit missed word. Link to comment Share on other sites More sharing options...
interestrateripoff Posted January 10, 2011 Author Share Posted January 10, 2011 You really need to know the cable size. If it is 4mm then no is the answer. Fortunately there are few cookers put in on 4mm so if the cable is the same as the cooker cable then there is every chance that it is 6mm in which case it is fine. The safest place to look at the cable is probably inside the shower. ISOLATE the shower at the fuse box by switching the circuit breaker off. Make sure that the shower circuit is dead. Whip the front off the shower and look at the cable, take it out if need be and find out if it is 4mm or 6mm. I have a problem with that the screw holding the screw cover in place appears rusted in, meaning the only way to check it is going to break off the shower cover I think. However it looks like I'll have to switch off the power to the shower and take apart the on/off switch at the top of the stairs. Link to comment Share on other sites More sharing options...
Harry Monk Posted January 10, 2011 Share Posted January 10, 2011 Disconnect the electrical supply and then just hammer/jemmy the old unit off of the wall. Then fit the new unit. Unless you develop a taste for hotter or longer showers, your old wiring will be fine. If your new shower unit does draw more current than your wiring is capable of delivering, your circuit breaker/ fuse will pop long before your wiring does, that's what circuit breakers and fuses are for. Link to comment Share on other sites More sharing options...
Number79 Posted January 10, 2011 Share Posted January 10, 2011 If you are into all that Hip Pak stuff (before they binned the idea) and electrical safety then the simple fact you are replacing the shower means you are duty bound to uprate the cable. If like me you are not then don't worry about it. Don't be tempted to fit a higher KW shower if you are in any way unsure about the cable. If it is rated to low then it will get hot possibly very hot and could combust all sorts of materials like old fag packets and insulation material that you have lurking under your floorboards. At the same time you not be naughty by checking the fuse rating in the consumer unit. Edit missed word. this isnt true, you can replace a shower no problem. There is no liability to uprate the cable even if it is the wrong size, which we dont know yet. It wouldnt be safe but he couldnt be touched for it. Link to comment Share on other sites More sharing options...
SarahBell Posted January 10, 2011 Share Posted January 10, 2011 Bathroom elecs is all part p. But get some quotes and grill the workmen as to what you need. Link to comment Share on other sites More sharing options...
Number79 Posted January 10, 2011 Share Posted January 10, 2011 Bathroom elecs is all part p. But get some quotes and grill the workmen as to what you need. new installation work in a bathroom comes under part p but replacing like for like appliances like light switches, light fittings, showers are not and can be done by any competent person. just like replacing fittings in a kitchen or outside. putting in a new shower comes under part p but when using the existing circuit you are not altering anything but the end appliance. The installation has not been altered. Link to comment Share on other sites More sharing options...
Bootsox Posted January 11, 2011 Share Posted January 11, 2011 this isnt true, you can replace a shower no problem. There is no liability to uprate the cable even if it is the wrong size, which we dont know yet. It wouldnt be safe but he couldnt be touched for it. Could there not be insurance implications if you ended up burning your own house down? Link to comment Share on other sites More sharing options...
Number79 Posted January 11, 2011 Share Posted January 11, 2011 Could there not be insurance implications if you ended up burning your own house down? possibly, insurance companies try to wriggle out of paying even when they are clearly supposed to. You could probably argue that the breaker is rated to trip before the cable could draw enough current to become a fire risk thereby making it irrelevant what appliance was connected to the end of said cable. The cable is protected by the breaker. The cable can take a max of 36amps, it should be on a 32a breaker tops. If I put an appliance on the end of the cable that could draw 90amps it doesnt matter in reality, the breaker will trip at 32a to protect the cable. There are some other issues that can affect breakers and cables but this is the basics in a nut shell. Link to comment Share on other sites More sharing options...
Sledgehead Posted January 11, 2011 Share Posted January 11, 2011 Any Shower Experts Out There? Need Kw On A Redring Well, you could start by ... ... hang on, it's just occured to me that this might not be a question about watersports and b*tt f**king after all ... Link to comment Share on other sites More sharing options...
geezer466 Posted January 13, 2011 Share Posted January 13, 2011 possibly, insurance companies try to wriggle out of paying even when they are clearly supposed to. You could probably argue that the breaker is rated to trip before the cable could draw enough current to become a fire risk thereby making it irrelevant what appliance was connected to the end of said cable. The cable is protected by the breaker. The cable can take a max of 36amps, it should be on a 32a breaker tops. If I put an appliance on the end of the cable that could draw 90amps it doesnt matter in reality, the breaker will trip at 32a to protect the cable. There are some other issues that can affect breakers and cables but this is the basics in a nut shell. Assuming of course the correct rated fuse/breaker is in place!! A check is a must, someone in the past might have stuck a rusty nail in.... You may jest but it does happen!! Part P requires that new installations reflect (and upgrades where necessary) to the latest regulations and or Codes of Practice. Whether a new shower unit falls under this category is a moot point. Whether or not it would need an upgraded cable would depend on what was in place, the Kw rating of the new shower and what was recommended in Part P. End of the day no one is going to come round and check it, nor need the installation date be referenced by any paperwork. It is not unknown for the rules to change from time to time and indeed Part P and supposed compliance to it is one of the changes implemented in the last decade or so. Currently all properties in commercial use are required to have their entire electrics checked and certified every 5 years. Whilst this doesn't apply to the domestic market it is not beyond the realms of possibility that it may do 10 years from now or on sale. Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 Currently all properties in commercial use are required to have their entire electrics checked and certified every 5 years. Whilst this doesn't apply to the domestic market it is not beyond the realms of possibility that it may do 10 years from now or on sale. Yeah, this isnt true either. It is a recommendation that there is a test and inspection of the fixed installation carried out every 5 years but is not enforceable. It is also recommended that domestic installations be inspected every 10 years or at the change of each tenancy but that doesnt happen either and is likewise, unenforceable. It is the same as many companies not having portable appliances tested or emergency lighting inspected annually, all recommendations. Link to comment Share on other sites More sharing options...
interestrateripoff Posted January 13, 2011 Author Share Posted January 13, 2011 Got a plumber coming round tomorrow so hopefully he'll know what he's looking at.... Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 Got a plumber coming round tomorrow so hopefully he'll know what he's looking at.... I wouldnt bank on it, thats why he is a plumber and bends pipes instead of installing installation units. Lots of my work has come from sorting out plumbers and kitchen fitters jobs, neither should be allowed to touch a wire imo. Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 Get an electrician in for a quote. There are only 2 options here. Either you have a 4mm cable probably on a 32a breaker which is fine for the shower that you have but not for the new one. Or you have a 6mm cable which is fine for the new one and would only require the breaker being uprated to 40a. A spark will tell you straight off what size the cable is. If it is 4mm then you have to decide what to do. The cable should be replaced with a 6mm but as harry pointed out the new shower should still work and the 32a breaker would trip if it tries to draw too much current. The breaker is there to protect the cable. This would not be according to the regs and there is a risk that you will have a shower that trips if you turn it too hot. If it is a 6mm cable then just pull the old shower off the wall and fit the new one. Dont worry about what anyone says about needing rcd's or anything else. That would be for a new installation and you are not obliged to meet the current regs with your existing installation when replacing a shower. If they tell you that it has to be done then they are fishing for work or dont understand. If you do need a 6mm cable installed then it is a new installation of the circuit, has to be done according to part p and I would let the spark do it because he knows what he is doing. Link to comment Share on other sites More sharing options...
jungllie jim Posted January 13, 2011 Share Posted January 13, 2011 possibly, insurance companies try to wriggle out of paying even when they are clearly supposed to. You could probably argue that the breaker is rated to trip before the cable could draw enough current to become a fire risk thereby making it irrelevant what appliance was connected to the end of said cable. The cable is protected by the breaker. The cable can take a max of 36amps, it should be on a 32a breaker tops. If I put an appliance on the end of the cable that could draw 90amps it doesnt matter in reality, the breaker will trip at 32a to protect the cable. There are some other issues that can affect breakers and cables but this is the basics in a nut shell. How is the cable routed....? If it's routed along the same run as other cables then the cable capacity needs to be downrated. The same goes with how the cables fitted and secured, is it been runder thru "kingspan" thermal insulation or under loft insulation? These all affect the cables capacity to disipate heat and therfore to carry 36A safely. You may need to uprate the cable size alond with the MCB in the consumer unit dependent on calculations. As for bathrooms they are areas of increased danger and thus special rules apply for equipment and location....Zones 0&1 and IP rating for electrical protection...IEE 17th Edition wiring Regs refer. Suggest that you also condsider a 30ma RCD or a RCBO (combined 30ma RCD &32/40A MCB) to provide earth protection in the event of electrical failure of the shower. The MCB in the concumer unit will protect your house and trip on over current but not a earth leakage. You'll need to get a qualifed electricain in the assess, fit and certify IAW current regulations. Also worth considering getting your ring mains protected ba 30mA RCD if the Electrician is going to have to be doing some work in the consumer unit and you have a spare way available. In short if the cable capacity is good then change the shower. If the cable needs to be replaced then you'll need to comply with current regs for that installation in this case the shower and regs state it needs to be protected by RCD. Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 How is the cable routed....? If it's routed along the same run as other cables then the cable capacity needs to be downrated. The same goes with how the cables fitted and secured, is it been runder thru "kingspan" thermal insulation or under loft insulation? These all affect the cables capacity to disipate heat and therfore to carry 36A safely. You may need to uprate the cable size alond with the MCB in the consumer unit dependent on calculations. As for bathrooms they are areas of increased danger and thus special rules apply for equipment and location....Zones 0&1 and IP rating for electrical protection...IEE 17th Edition wiring Regs refer. Suggest that you also condsider a 30ma RCD or a RCBO (combined 30ma RCD &32/40A MCB) to provide earth protection in the event of electrical failure of the shower. The MCB in the concumer unit will protect your house and trip on over current but not a earth leakage. You'll need to get a qualifed electricain in the assess, fit and certify IAW current regulations. Also worth considering getting your ring mains protected ba 30mA RCD if the Electrician is going to have to be doing some work in the consumer unit and you have a spare way available. In short if the cable capacity is good then change the shower. If the cable needs to be replaced then you'll need to comply with current regs for that installation in this case the shower and regs state it needs to be protected by RCD. Yes, I pointed out that the cable can take a MAX of 36a and should be on a 32a breaker. The worst case scenario is if the cable were 4mm and run completely through insulated walls in which case It should be down rated to about 26a from memory. But on a 32a breaker the cable will not get to the max of 36a and there is a substantial safety margin built into to cable calcs anyway. The post that you quote was in response to a comment about fire. I stated that "The cable can take a max of 36amps, it should be on a 32a breaker tops. If I put an appliance on the end of the cable that could draw 90amps it doesnt matter in reality, the breaker will trip at 32a to protect the cable. There are some other issues that can affect breakers and cables but this is the basics in a nut shell." The other issues being the possible installation method but this is the basics in a nut shell. The assumption, we all know what they are, is that the cable was installed correctly in the first place and likely runs under the floor most of the way rather than through insulated walls or cramped with other cables. The few other cables that may run up stairs shouldnt be an issue though. All the regs apply to a new installation. I dont disagree that an rcd would be a preferred option but I dislike people being lied to and told that they have to have it fitted. He should know exactly where he stands so that he isnt screwed over which is all that I have tried to do. It is only the downstairs ring that should be protected by an rcd as that is the ring likely to provide power externally. It is there to prevent you from being killed when you are outside of the earthed zone (house) if you run over a cable with your lawnmower etc etc. Link to comment Share on other sites More sharing options...
jungllie jim Posted January 13, 2011 Share Posted January 13, 2011 Yes, I pointed out that the cable can take a MAX of 36a and should be on a 32a breaker. The worst case scenario is if the cable were 4mm and run completely through insulated walls in which case It should be down rated to about 26a from memory. But on a 32a breaker the cable will not get to the max of 36a and there is a substantial safety margin built into to cable calcs anyway. The post that you quote was in response to a comment about fire. I stated that "The cable can take a max of 36amps, it should be on a 32a breaker tops. If I put an appliance on the end of the cable that could draw 90amps it doesnt matter in reality, the breaker will trip at 32a to protect the cable. There are some other issues that can affect breakers and cables but this is the basics in a nut shell." The other issues being the possible installation method but this is the basics in a nut shell. The assumption, we all know what they are, is that the cable was installed correctly in the first place and likely runs under the floor most of the way rather than through insulated walls or cramped with other cables. The few other cables that may run up stairs shouldnt be an issue though. All the regs apply to a new installation. I dont disagree that an rcd would be a preferred option but I dislike people being lied to and told that they have to have it fitted. He should know exactly where he stands so that he isnt screwed over which is all that I have tried to do. It is only the downstairs ring that should be protected by an rcd as that is the ring likely to provide power externally. It is there to prevent you from being killed when you are outside of the earthed zone (house) if you run over a cable with your lawnmower etc etc. Nothing to stop all circuits being protetced by a single RCD after the main 100a breaker.Space allowing and assuming there is no fire alarm fed from the consumer unit. Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 Nothing to stop all circuits being protetced by a single RCD after the main 100a breaker.Space allowing and assuming there is no fire alarm fed from the consumer unit. True but I would rather have a split board or be able to have some circuits not protected by the rcd. Everything going off each time a light bulb goes is pretty annoying but not as much as finding a freezer full of defrosted food because the rcd tripped while you were out/away. I cant remember the reg but there is one about rcd's not causing unnecessary disruption which to my mind is clearly broken if everything in the house goes off because a light bulb blew. Link to comment Share on other sites More sharing options...
jungllie jim Posted January 13, 2011 Share Posted January 13, 2011 True but I would rather have a split board or be able to have some circuits not protected by the rcd. Everything going off each time a light bulb goes is pretty annoying but not as much as finding a freezer full of defrosted food because the rcd tripped while you were out/away. I cant remember the reg but there is one about rcd's not causing unnecessary disruption which to my mind is clearly broken if everything in the house goes off because a light bulb blew. Totally concur regarding split boards and splitting circuits,but current regs state that if CU needs replacing then light, power and Elec circuits and equipment in higher risk areas need to have RCD protection.Replacing of a CU being classed as a installation and not minor works. BS7671 2008 is the rules and the rope for HSE to jail/Fine if you do not comply WRT any installation being no less safe than required by the regs. WRT the original post if the cables good then great, if not and needs replacing it needs either a RCD or the shower MCB replacing by a RCBO . If the CU if fully populated then it's an RCBO in the CU or fitting a RCB external the the CU.......How about airing cupboard if it backs onto the bathroom allowable and easy for access. Link to comment Share on other sites More sharing options...
northwestsmith2 Posted January 13, 2011 Share Posted January 13, 2011 What shower needs 42amps, you're not hiding a hottub are you? Fairgrounds get by on far less. Link to comment Share on other sites More sharing options...
Number79 Posted January 13, 2011 Share Posted January 13, 2011 Totally concur regarding split boards and splitting circuits,but current regs state that if CU needs replacing then light, power and Elec circuits and equipment in higher risk areas need to have RCD protection.Replacing of a CU being classed as a installation and not minor works. I know what the current regs are but replacing the consumer unit was never being discussed or considered here. It is not even a consideration and as I pointed out in an earlier post, if the cable needs to be replaced with a 6mm then it needs to be done by a spark and an rcd fitted. Personally, I think if that were the case then it makes far more sense to have a stand alone rcd unit fitted up stairs rather than replace the consumer unit. BS7671 2008 is the rules and the rope for HSE to jail/Fine if you do not comply WRT any installation being no less safe than required by the regs. Funny thing about part p. It is a statutory requirement that work be carried out in accordance with the regs. But the regs are not a statutory document, they are for guidance and you are under no legal obligation to abide by them. Of course if something goes wrong then your only defence is that you have worked to the current regs and if you have not then you are toast but there it is. Legally required to work to a set of regs that are not legally binding and there for guidance. I am waiting to see how the first few prosecutions go, could be interesting. WRT the original post if the cables good then great, if not and needs replacing it needs either a RCD or the shower MCB replacing by a RCBO . If the CU if fully populated then it's an RCBO in the CU or fitting a RCB external the the CU.......How about airing cupboard if it backs onto the bathroom allowable and easy for access. he already has a shower circuit so there is a space on the board. Stand alone rcd unit would be my choice in the airing cupboard, if not then the wall outside the bathroom. edit to add - I see that I hadnt made it clear that an rcd would be required if a new cable needed to be installed but did make it clear that a spark should do that job because he will know what he was doing. I was more interested in preventing him from being billed for unnecessary work tbh than giving him a full description of the job. Link to comment Share on other sites More sharing options...
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