Garden Room Workshop: Part 14. First fix Electrics & Plumbing transcript

in the last video I laid the utilities between the House and Garden Room and in this video we'll cover first fix electrics and plumbing so first off how do we know what size armored cable we require this depends on what electric components you have in your garden room so let's work backwards starting with lighting the brightness of lights is measured in lumens and Lux is a measurement of lumens per meter squared the minimum amount of light required for perception of detail is 200 Lux as my garden room is 30 meters squared I could have 3200 lumen down lighters that's not really practical the main area of my garden room is 27 meters squared 200 Lux times 27 meter squared equals 5,400 the actual town lights I'll be using are 520 lumens each so five thousand four hundred divided by five hundred twenty equals ten point four so the minimum number of Lights that I'd need to get 200 Lux is 11 because we round up I wanted to divide my main room into two circuits one for this area and another for this area so my electrician and I settled on nine and four totaling 13 so it should in fact be brighter than 200 Lux but there'll be on a dimmer switch so I can adjust that as needed bathrooms tend to need brighter light at 320 lux so if we do the same calculation for my shower room 320 lux times roughly three meters squared equals nine hundred and sixty nine sixty divided by five hundred 20 lumens equals one point eight so the minimum number of lights would be two but we went for three I think it's well worth going for external lighting to wall lights next to the main door is a nice option but I decided to just have six down lights in the soffit at the front these will be of similar power to my internal ones so in total I will have twenty two lights of seven watts each which equals one hundred and fifty four watts 154 watts divided by 240 volts equals naught point six four amperes not a lot in the UK a residential property requires a six amp fuse probably because older halogen bulbs require a lot more power than the LEDs we use today but I'm going to show you this calculation here as we'll be using it for other devices later on in the video but as long as you're using LED lights you could have as many as 200 and the mandatory six amps will still be enough anyway we now know how many lights we'll need and we can add those six amps to our consumer unit next up heating just to cover all the options you can run a gas line to your garden room for a boiler or indeed hot water pipes straight from your house if your garden room isn't too far away but that's already practicable for our purposes another option is a wood-burning stove which I love but for most of us electric heaters will be the go-to method if you Google electric radiator calculator there are various web sites where you can input the size of your space and various other metrics to tell you the power of radiator you'll require I'll be using q-rad dimplex radiators and their calculators came out with a four kilowatt radiator as I'll have one on either side of the room I'll be using two two kilowatt radiators we could do the same calculation as before four thousand watts divided by 240 volts equals sixteen point six amps so we'll add 17 amps to the consumer unit so that's the easy way however the calculators make assumptions about you values and number of exposed walls which are inaccurate for my build so while I try to keep this series to a need-to-know basis I've talked a lot about you values in past videos and spent a considerable amount of time and money on insulation so just for fun let's delve deeper into this topic as a quick aside if you're in the US or elsewhere where insulation comes in our values you can use this simple equation so what do those characters after the U value number actually mean u value is measured in watts per meter squared Kelvin let's expand this so u value equals power watts divided by surface area meter squared divided by tempor differential Kelvin rearranging this equation we have power which is what we're trying to work out equals u value times surface area times temperature differential first up is U value each of my mediums u values differ so we have to break it down into floor roof walls and windows and doors the U values for the floor and roof I calculated in part six or nine the walls I've now insulated so I have that figure too and the windows you value I've taken from the suppliers website the second part of the equation is surface area each of the mediums has a different internal surface area length times width my floor is just over the 30 meter squared building regs rule but comes under when I include the footprint of my showroom stud wall but for this purpose we want the whole area the roof is pretty much the same as the floor but just slightly more because it's sloped the windows and doors you can either measure or find the dimensions from your invoice and lastly the four walls are added together - the windows and doors for each of the mediums I can multiply the two columns together and then total them up and that's the first two parts the equation dealt with temperature differential the coldest it gets in London is give or take around minus three degrees Celsius during the day when I'd be using the Garden Room and let's say I want it to be 21 degrees inside the garden room that's a temperature differential of 24 degrees or 24 Kelvin Celsius and Kelvin move up and down on the same scale so thirty four point six three times 24 Kelvin equals more or less 831 watts required to maintain that difference in temperature for that cold winter's day example so let's say I wanted to use my garden room as an office for eight hours a day well that's naught point eight three one kilowatts an hour times eight hours times let's say fifteen pence per kilowatt hour which equals less than a pound a day to heat your garden room of course on a warmer day it would be even less now we use our other equation to turn it into amps 831 watts divided by 240 volts equals three point four six amps so the time and money spent insulating actually gives me a pretty good return but why the difference in amps from the heat isn't going for well you have to heat everything in the garden room up to that temperature from cold so you need extra power to do that the more extra power you have over and above the amount required to maintain the temperature differential the faster your garden room will come up to the desired temperature if you want the room to heat up quickly fit more powerful heaters if you will always have the heaters on so they're maintaining the temperature long term you need much smaller heaters a bigger heater doesn't hurt course as whilst it would draw more power it will switch off sooner but it does mean that you'll need a bigger power cable and the cost is higher too so hopefully that was interesting you know do plug your own you values and surface areas in and see what the cost comes out at I'd be interested to know electricians generally don't go into these figures and instead rely on the calculators shown at the start and to be fair this is just the beginning of the rabbit hole of calculations you can do as it doesn't take into account things like air tightness or thermal mass so just to clarify this figure gives me a good indication of the average power consumption but I still need those 17 amps as my heaters will turn on have a spike of consumption and then turn back off again so as I said this is just a bit of fun to make us feel good about insulating our garden rooms and it's quite dusty job so there's your encouragement so last point I want to make on heating is that a great option is a wall-mounted heater / air-conditioner but you do need the space on the outside of the building for the heat pump so that's why I didn't go for it so let's rattle off the rest I decided on having an alarm fitted and while it draws little power like the lights will need the six amps standard current rating the electric shower I chose is 9.5 kilowatts and for every kilowatt extra in power you get about 12% more flow without the temperature dropping but whether you go for seven point five or ten point five kilowatts it requires a significant amount of power and my nine point five kilowatt translates to thirty nine point five amps similarly I wanted my tap to produce warm water and got a four point four kilowatt heater I'm slightly skeptical as to whether this will do the job we'll have to wait until the second thinks to find out but we'll add eighteen point three amps the sockets are on a pretty standard 32 amp circuit and lastly back to heating I'm only putting acoustic insulation between the main room and the shower room so a good amount of warmth or should transfer across but I'll be installing a wall-mounted fan heater above the door to warm the shower room quickly should it be needed Dimplex again supply these at two kilowatts which is eight point three amps so that's everything now to work out what size cable we need we first need to take out the highest rated device which in my case is the shower at 39 and a half amps we then total up the rest which comes to 87.6 you then multiply that figure by 0.4 which equals 35 point zero four amps for me you then add back in the highest rating device which equals seventy four point five four amps we then want to add 10% so we can multiply that figure by one point one which for me equals eighty two amps why this calculation I hear you ask well it's taken from this guide and I believe it's to do with the fact that you won't be using every device all at the same time which makes sense but I'm not clear on the exact mathematics so I'm just accepting it as an in a leotard for me to do as I always want to know why something is the way it is anyway now that we have that figure we can make our way over to a website called Doncaster cables the links in the description select the following single phase three phase not to be confused with three core is usually for commercial buildings only while single phase is residential five percent voltage drop as I understand it this is lost as heat throughout the length of the cable the figure you calculated in amps in my case 82 the length of the cable from the consumer unit in the house to the consumer unit in the garden room mines around 25 meters and select directed ground if yours is buried mines about 50/50 above ground and below ground but I've selected both and they both came to this same size cable so click calculate and scroll down until you find the armored cable and as you can see mine came out at 16 millimeters squared and that's the size cable you saw I put in in the last video and the reason why I couldn't use the original cable that ran to my old garage if you don't have an electric shower or have a smaller garden room than mine then it's likely you won't need such a large cable but I'd recommend going bigger than you need in retrospect I might have gone for 22 or 25 millimeters squared cable because you just never know when you're gonna take up welding and need that extra capacity of course the thicker the cable the more expensive it is so as usual there is a trade-off you want again SW a three core excel PE armored cable prices vary quite dramatically and I got mine from a local shop rather than which turned out to be cheaper so do look about so let's follow the cable at the garden remand mine came up near my shower room and then I tucked it behind the block peers after which it pops up to the left of the main doors as this will be where my consumer unit is so the consumer unit needs to be a minimum of 45 centimeters from the floor and you need around 30 centimeters of excess armored cable to go inside the consumer unit all the cables for the circuits I talked about then come out of here so where can cables go and where can't they go there are safe zones which span out horizontally and vertically from sockets which is Isolators and few Spurs additionally you can run cables along the top of your walls and in the corners both inside and outside corners and of course in the ceiling too this is so the next unsuspecting person who comes along doesn't try to drill a wall here and get a nasty shock in the next main video in this series I'll show how I insulated my walls but there's no doubt about it the wiring does rather get in the way however because I have a warm roof I have an advantage because the space between my joists will have no insulation and is totally free to run cables in so instead of going around my stud wall the majority of the cables in my walls drop down from the ceiling to the sockets and switches a cold roof design doesn't entirely preclude doing it this way but it may make everything a bit more fiddly especially if your joists on that thick however you'll want lights in the ceiling so you'll at least have some wires so where do you cut holes so let's take an example of a four meter span and a joist depth of 200 millimetres no holes should be cut within the first quarter of the span that's 1 meter in in this case and no further than naught point 4 of the span that's 1.6 so that leaves two sweet spots the holes should then be drilled right in the center line of the joist each hole should have a diameter of no more than a quarter of the depth of the joist so here our maximum hole size of 50 millimeters and lastly holes should be spaced no closer together than three times the diameter of the holes so again in this case no closer than a hundred and fifty millimeters these are the building regs for floor joists to ensure structural integrity is maintained but don't seem to apply to roof joists but I think they are worth bearing in mind so you can drill through with confidence my electrician did stray into the end zone but I don't think it's a big deal cabling in the walls shouldn't be completely surrounded by insulation as this can lead them to overheat and reduces the current carrying capacity one way to get around this which is what I have is for the cables to be threaded through PVC conduit which provides air space around the cable to allow heat to dissipate and it makes quite a difference take a look at this table for my 9.5 kilowatt shower which is thirty nine point five amps you would usually specify a ten millimeter cable in conduit like mine it will deliver 44 amps which is sufficient if it were in a masonry wall with no insulation I get as much as 64 amps but if the cable is surrounded directly by insulation the rating would just be too low so as you can see this is an important point so here's another table for a 2.5 millimeter cable with diagrams having the cables touch your clip to an inner or outer wall also helps with heat dissipation other options are to leave space for wiring at the front or back of the wall though this does mean thinner insulation and if your cables are going horizontally across your studs with your cable you really want to be going through the middle of each stud rather than notching out the front or back another option is to go ahead and fill the stud wall void with insulation but then put battens over the studs to create a space for the cables at the front but that has the drawback of eating into your room space you'll also want to be mindful when you are attaching plasterboard of where the wires are so you don't put a screw through one if you opt to put the wiring at the back then I highly recommend putting your external buttons for the cladding on before you do the electrics doing mine recently made me a little nervous I must say another option I've seen done is installing the wiring behind the skirting board however because of the safe zones you'll only be able to put sockets at the same level ie in the skirting itself to exhaust all methods if you really want to minimize wiring then you can use wireless switches for your lights where the act of pressing the switch generates enough energy to send a signal to the receiver to turn the lights on or off which means the only things that you need to wire up in your wars are your sockets to sum up the desire for a warm well insulated garden room without excessively thick walls is in conflict with what's good for electrics and you just have to make the best of it in terms of the circuitry I have a sketch of the original layout we were planning though as you can see we made quite a few changes but hopefully it gives you an idea I'm not going to go into circuitry or running wires because that would be a series unto itself and way beyond my understanding which is why I decided to hire an electrician Andrew to do it all and provide the safety certificate in fact making this video has taught me quite a lot about my own strengths and weaknesses as it turns out I'm quite good at visualizing floor plans layouts and physical structures and I can make analogies to comprehend them I'm really poor at understanding things I can't visualize like electrons whizzing down wires you might be different and want to do the electrics yourself however in the UK you do need the work to be signed off by your local council which will usually mean two visits want to check wiring paths and a second test before they'll give you a certificate the cost is upwards of three hundred and forty pounds if you have a mate who is a registered electrician they're not supposed to sign off others work but I've heard that it does happen personally I'm not a stickler for rules but in the case of electrics I do think it's important to go by the book when all was done Andrew gave me a rundown of what everything was and which cables should poke through the plasterboard and we're right on to plumbing I've seen dozens of your builds now over email and I'm yet to see one where the shower room so I'll keep the section brief the twenty five-millimeter mdpe poly pipe laid in part thirteen is deep enough to be below the frost line but where the pipe comes up at each end it needs to be insulated to prevent the water in the pipe from freezing and there a special pipe installation for this very task at the house side I have a pipe running to an outdoor tap so my plumber Wesley tapped into that and added a stopcock so that I could isolate the water to the garden room in case there was ever a leak without affecting the water supply to the house there are two options for piping you can use copper pipe like Wesley did which requires soldering or more DIY friendly is barrier pipe which is flexible so can be bent around obstacles and has push fit fittings rather than having to solder pepto seems to be a popular brand baaz i wasn't doing the job I didn't mind which was used so at the Garden Room and my MDP pipe comes up through the floor and converts to copper there was a branch to fill the toilet system and the waste from the toilet also goes through the floor which like my shower tray sits between the floor joists to the right the water travels to my shower where my 10 millimeter power cable in conduit is to and Wesley also attached waste for the shower tray to the left I have two pipes to the sink in case I ever want increased pressure or two taps although I'll be adding insulation to these walls these pipes were insulated as well there's another cable at the sink for the heater and also the waste pipe as well of course and finally under the floor we can see these three waste pipes all connect to the main waste pipe laid in the last video so if you've made it to the end of the video thank you I know it's been away so I think you all deserve to see where I am in real time so I'll throw up some photos while I do a bit of talking firstly I want to say a big thanks to Ben from the last video Andrew and Wesley for being good sports by going on camera they've all done a terrific job so if any of you live in the southeast and want their contact details feel free to email me as I alluded to earlier this video isn't my preferred topic but I wanted to cover the subject of electrics as best I could as I felt this series would be incomplete without it and I've learned a lot creating it obviously I've gone into depth on some things like the u-values and scattered over others like circuitry but I hope it's clarified some things for many of you and will come and useful even if you do hire an electrician I'll give a complete tour in the second fix video of where all my sockets and things are but you should spot them in the next main video where we get back to the action with a helping hand from a friend of mine in which we find a novel way of cutting insulation talk about vapor barriers one last time and possibly get into plaster boarding as well thanks for watching please do give it a like if you found it useful and I'll see you soon