Chris Pearson:

I can understand the satisfaction obtained from doing the work oneself and as a surgeon, jimmyhorns presumably likes fixing things with his hands.


That's the easy bit!


It occurs to me that the existing narrower ceiling does not need acoustic insulation because it must be no worse than it was previously. (R.4(3) of BR 2010). If the building control wallahs want it in the new bit, best to put it in, but the taller void will make it easier.

 

My thoughts were exactly this - the old ceiling does not need 'improvement' as it will not be any worse than it was previously and is not dangerous. I conceed to David's superior knowledge of the soundproofing issues. Due to ceiling height considerations dropping it further in the new kitchen section would not be practical - what you say does make perfect sense in terms of the difference in mechanism of actions of the differing types of insulation.


Building control's approach on this is that it is a new single room, rather than an old room and a new room. The existing rear wall of the property, (apart from 2 x 700mm piers that come out from the wall to support the 6 metre steel) disappear. On the basis that this is a new room, and this area of the room has a change of use into a kitchen, now requires different ventilation / extraction and fire detection I can live with the notion that this is 'new' rather than existing. I also note that part E only applies to new builds. 


I have already had conversations regarding the above and BC have been very reasonable about some other aspects of the build that could have ended up being very expensive to solve but common sense prevailed. I am not up for the fight on this if there is now a solution, even if this means a bit of extra work for me... life is just too short :)



Well the first bit of the electrical notes:


Supply and Main intake:


Single phase, 230V 25mm2 supply into 100 Amp cut out (Henley series 7) with TN-C-S Earth system


25mm2 meter tails from cut out to 80 Amp (non-smart) Meter


25mm2 consumer tails and 16mm2 Earth to Switch Fused unit (100Amp) and then into 100Amp Dual RCD consumer unit.


Planned circuits with diversity calcs:


Lighting 1 - 20 x 10W luminaires (All LED) = 200W = 200/230 = 0.87 Amps, applying 66% diversity =    0.56 Amps

Lighting 2 - 30 x 10W luminaires = 300W = 300/230 = 1.3 Amps, applying 66% diversity =                     0.86 Amps


Immersion Heater - 3000W = 3000/230 = 13 Amps. No diversity =                                                           13 Amps

Cooker - 4800W = 4800/230 = 21 Amps, applying diversity 10 = (0.3x11) = 10 + 3.3 =                            13.3 Amps


Ring final 1 = 32 Amps full load. No diversity applied                                                                                 32 Amps

Ring final 2 = 32 Amps full load, applying 40% diversity = 32 x 0.4 =                                                        12.8 Amps

Ring final 3 = 32 Amps full load, applying 40% diversity = 32 x 0.4 =                                                        12.8 Amps

Garage radial = 32 Amps full load, applying 40% diversity = 32 x 0.4 =                                                    12.8 Amps


Total maximum demand applying diversity =.                                                                                             98.12 Amps





So the first issue I get to is that it is unclear whether the supply is rated for 100 Amps (though the cabling is, the meter isnt and the DNO may not specify a 100A supply)


Any flaws so far?


 

jimmyhorns:

Any flaws so far?

Yes, if you plugged everything in and switched on, how much current would it add up to?


If you had only 2 ring finals in the house, you would subtract 12.8 A from the above, but the overall load would be the same.


32 A is a lot for a garage unless you have an EVCP. Could be 1 x 3 kW heater, but then what?


Try dividing your annual consumption by 365, then 24, and finally 0.23: that will give you your average load. It won't be much.

Chris Pearson:

jimmyhorns:

Any flaws so far?

Yes, if you plugged everything in and switched on, how much current would it add up to?



32 A is a lot for a garage unless you have an EVCP. Could be 1 x 3 kW heater, but then what?

 

I thought that was the purpose of diversity - to correct for the fact that everything is unlikely to be on at the same time.


To answer your question, with everything plugged in and at full capacity, a lot of Amps, but in practice I cant see that happening.


For example, the immersion heater 'never' gets used etc.


In reality the cooker, washing machine, tumble dryer, hairdryer, full garage load and the lights are all that would be on simultaneously which would give:


21+13+8+32+2 = 76 Amps


The garage is more of a workshop and garage. 3kw heater + 4kw compressor + Mill + lathe + Plasma cutter + (insert any of the other toys here). Average demand is actually very low, but if its cold, the compressor kicks in while I am using the plasma cutter you are looking at 13 + 20 + 13 amps so already over spec - I'm careful with what runs simultaneously of course limiting it to one machine if the heater is running or two machines if it isnt.

jimmyhorns:

The garage is more of a workshop and garage. 3kw heater + 4kw compressor + Mill + lathe + Plasma cutter + (insert any of the other toys here). Average demand is actually very low, but if its cold, the compressor kicks in while I am using the plasma cutter you are looking at 13 + 20 + 13 amps so already over spec - I'm careful with what runs simultaneously of course limiting it to one machine if the heater is running or two machines if it isnt.

Hm! How is the compressor wired in?

Hm! How is the compressor wired in?

32 Amp radial to Garage consumer unit to 20 Amp MCB to 6mm2 SWA to Single - 3 phase inverter to 3 phase motor of the compressor.


Using a 3 phase motor and running an inverter avoids the horrific start up currents and also allows speed control and avoids on-off cycling when the air drawn off is fairly constant. I designed/built the microcontroller circuitary that controls the inverter to predict / adjust demand.

jimmyhorns:

Hm! How is the compressor wired in?

32 Amp radial to Garage consumer unit to 20 Amp MCB to 6mm2 SWA to Single - 3 phase inverter to 3 phase motor of the compressor.


Using a 3 phase motor and running an inverter avoids the horrific start up currents and also allows speed control and avoids on-off cycling when the air drawn off is fairly constant. I designed/built the microcontroller circuitary that controls the inverter to predict / adjust demand.

And with that level of sophistication you worry about a bit of wadding in a ceiling? ??


My 3 hp compressor eats 13 A fuses for breakfast (on start-up), but at least I have not adopted my chum's solution which is to insert a nicely turned bit of brass rod into the fuse holder. It may not be as bad as it sounds. At a steady state, the motor could not overload a 13 A fuse and under fault conditions, the MCB should trip.


Note, please do not do this at home. ?