Holiday let sleeping 8+. Gas ch (combi) and cooking. 2 x Wylex rewireable cu's, pme (6mm earthing conductor!), no rcd protection. 16mm dno supply, prob 100A dno fuse, no rating on meter but likely to be 80A
1 x cu for normal (lights, rfc's) etc. 2nd cu 60A rating with 3 x 45A fuses feeding 3 x 9kW showers.
Was called in for simple switch replacement today and discovered above without looking too hard!
It is entirely feasible that holidaymakers return home from beach, kettle on, clothes in wash machine and all go for showers at the same time.
I am going to inform customer by letter of my findings and it would be nice to offer a solution. As I see it the possibilities are :-
1) Plumbing solution. Pretty new Greenstar combi so no stored water so not realistic
2) Supply upgrade. Overhead supply now undergrounded, told that rising feed unlikely to have the additional capacity required (even though don't want to increase demand, just want to comply with 7671) so likely to be very expensive
3) Reduce demand with something like Garo 3 way non-priority shower unit (from Meteor) but not really at all satisfactory.
4) Post problem on forum and pick peoples brains.
An additional problem is that it has been this way for 10+ years without the dno fuse popping or the house catching fire so may be difficult to convince the customer of the need for any work.
Another thought I have had is to replace the shower cu with an 80A mcb supplying 3 x 32A mcb's for the showers as a way of limiting the load. So 16mm from Henleys into 100A main switch, N out to dp rcd, L out to 80A mcb supply, 80A L load to dp rcd in, assuming I can get supply upgraded to 25mm (or if dno don't care using existing which is buried for 3m in render). Far from ideal but a crude way of limiting demand by use of an mcb.
Another variation of this (and to my mind better) is to have one cu for the whole house, one shower off a 32A mcb with another 32A mcb supplying a 2 way shower priority switch, such as the Garo 2 way. I have then limited my short shower demand to around 70A leaving 30A for the rest of the house.
Comments / advice / solutions welcome please. In true op stylee I am shortly going out overnight so will not be able to respond until the morning
1 x cu for normal (lights, rfc's) etc. 2nd cu 60A rating with 3 x 45A fuses feeding 3 x 9kW showers.
Was called in for simple switch replacement today and discovered above without looking too hard!
It is entirely feasible that holidaymakers return home from beach, kettle on, clothes in wash machine and all go for showers at the same time.
I am going to inform customer by letter of my findings and it would be nice to offer a solution. As I see it the possibilities are :-
1) Plumbing solution. Pretty new Greenstar combi so no stored water so not realistic
2) Supply upgrade. Overhead supply now undergrounded, told that rising feed unlikely to have the additional capacity required (even though don't want to increase demand, just want to comply with 7671) so likely to be very expensive
3) Reduce demand with something like Garo 3 way non-priority shower unit (from Meteor) but not really at all satisfactory.
4) Post problem on forum and pick peoples brains.
An additional problem is that it has been this way for 10+ years without the dno fuse popping or the house catching fire so may be difficult to convince the customer of the need for any work.
Another thought I have had is to replace the shower cu with an 80A mcb supplying 3 x 32A mcb's for the showers as a way of limiting the load. So 16mm from Henleys into 100A main switch, N out to dp rcd, L out to 80A mcb supply, 80A L load to dp rcd in, assuming I can get supply upgraded to 25mm (or if dno don't care using existing which is buried for 3m in render). Far from ideal but a crude way of limiting demand by use of an mcb.
Another variation of this (and to my mind better) is to have one cu for the whole house, one shower off a 32A mcb with another 32A mcb supplying a 2 way shower priority switch, such as the Garo 2 way. I have then limited my short shower demand to around 70A leaving 30A for the rest of the house.
Comments / advice / solutions welcome please. In true op stylee I am shortly going out overnight so will not be able to respond until the morning