Electricity question

[Patience]

Hope those skilled in the arts of electrons can help.  Does a 220v oven element need to have a fuse?  I plan on running 220V 4 wire with one leg+neutral that will run the PID, smoke generator and convection fan (w/their own fuses) and just the hot wire will also connect to one terminal of the element.  The other leg will be switched on/off thru the SSR and connect to the other side of the element.  Since these things are pretty cheap, do I really need a fuse between the SSR and element?  What am I risking without one, a blown element?

If so, what size would I get if I were to be running the whole works off a 20amp 220v breaker.  The element will be rated at 2400 watts.

[beefmann]

Paatence,

I am an electrican by trade. I  would fuse both legs into the bradley, controll box at 20 amp, then i would fuse both  legs to the heater at 12 amp before the connection to the  heater on  the  one side and to the ssr on the  other.

if the rest of the unit  is 120 volt i would put the controller and fan on one hot leg andthe neutral, and the smoke generator on the other leg and neutral. this way you  would ballance the load and your  220 volt heater across both hot legs. ground only the metal case of the smoke generator and the metal tower.

this way you  have  ballanced the load across both legs as  much as possable though it wont  be 50 / 50 if you are  smoking and  cooking at the  same  time.

to calculate the current the formula is  wattage devided by voltage gives amps

2400 watts / 240 volts = 10  amps... 10 amp might blow at  some point in time .. be a bit  larger then needed

hope this  helps


beefmann

[Patience]

Yes, this helps a lot.  If I already have the 20 amp 220v breaker at the service box, are the 20 amp fuses between it and the electrical box of the smoker just for added security?  Also, is there a specific fuse holder used for large guage wire like that? Also, thanks for the tip on running the SG off the other leg. 

My next question is what guage wire should I run.  I was planning on 10/4 from home service to the receptacle in the garage (about 50 feet), then atleast a 4 foot chord from smoker to to the receptacle.  The chord on my dryer says 8/2+10/1 and I assume the 10/1 is the neutral used to run the 110v electronics of the dryer and the 8/2 is for the element terminals.  Do they make a simlar size chord with the ground in it as well?  If so, that would be perfect as far as I can tell.

So, would a dryer chord w/ground be ok, or should I make my own out of 10/4 wire (I don't care if its not as flexible as the dryer chord)

Thank you again!

[beefmann]

if you  have 10 / 4 already yes u can use it... and  if it is on a electric dryer 240 volt dryer circuit  it is at 30 amp typically so use  10 / 4

black and red are your  hots the white is your neutral and the green is your  ground.

what you can do and i recomend is on the 10 / 4 is put a 30 amp plug at the end of where the dryer / range recptical is so all you  have to  do is plug  it in. then adapt how evewr you  want at the other  end.. a good recomendation would be  useing  a  30 amp 125/ 250 volt twistlock female cord end recptical on the cord you  would run  the 50 or  so feet to the smoker.

at the smoker put a 30 amp 125 /250 volt male and into your  controll box / smoke generator and some 10 - 4. at this point put 2  case mount fuse holders rated at  30 amp each. ( you  can fuse  smaller ie 20 amp ) after that i would add a few smaller  fuses  such as both legs to the 230 volt heater, fuse to the PID, fuse the fan / blower( look at the blower amps and add 20 % to it to get fuse  size. and any other devices.

this is just  being a bit  cautious and a little over kill.. though it is better safe then sorry  down the road..

one miss-wire and you  can  damage everything,,

when you go to fire up your  unit for the first time .. take  extra time and only  add  fuses to one  item at a time,, starting  with the  timer,  smoke generator, fan then your  heater... at  each  point check and turn on in each fused  step to check to see if it is wired correctly.. if you fised the timer and put the fuse in it  should be the only thing operating..

then ass the fuse for the blower and  check to see  that it  works along with the  timer
then on to the  smoke generator and  confirm all three works
and finally the  heater and  confirm that all  works properally

taking extra time will prevent problems later

make the cord from the controller long.. 5 to 10 feet so you  can have it  available and in easy  reach so you wont  have to scramble to  unplug it

good luck and hope this is good information

[Patience]

ok, I think I understand the wiring setup now.  I would have just put it all together and turned it on, but now I will do as you recommended w/only turning one thing on at a time (by adding each fuse)  down the line I will try and paintshop a schematic and post it.

One final question, as far as elements go.  Do I just get a 30 dollar oven element that I can buy spare ones and have on hand or do I spring for a fancy infrared element thats thrice the cost (Bradley uses this type?) which claim they heat up faster and cool down faster thus making the PID work more efficiently.  Each time I research I come up with another possiblity that looks better.  Any thoughts?

Oh yea, regardless of which element, do I keep the entire element (terminals w/good high temp wiring) inside the shell of the oven, or do I attempt to atleast get the terminals outside the shell like typical household ovens and hook up terminals with regular wire.  Thoughts on this?

Thanks again for your input.

Patience

[beefmann]

you might consider a finned heater much like here ( copy and paste  link to browser ) it is a 900 watt heater and it is one that i  use .. currently have over 300 hours on it and no problems as you  see it  configured


http://forum.bradleysmoker.com/index.php?topic=7203.0

if you like the setup you  can get the blower and heater at  Graingers  The blower is aan updraft for furnaces and the  heater is rated for food service..

finned heaters can be quite usefull

as for the terminals andconnections i would leave as soon as possable  the interior food cabinit to the void between the interior and the exterior, if possable run high temp wire of at least 250 degree C or like 500 degree F for the wires the higher  the better - from the heater  to the controll  min. 18 inch from the heater

oh yeah bypass the heat limit switch on the back of the bradley and let the heater be controlled by the PID .. if you  want to use a simular infared heater  like what bradley does go for it .. though i think 2400 watts is a bit  much when im running only  900 watts in a finned heater and have had no problems  doing  40 lbs  food and it will pretty  much  hold any  tempture that  you  give it.. have been as high as 350 though i normally run between 190 and 230 with zero problems. of course everything is fused

beef

[beefmann]

btw if you  decide to use a fined heater like mine be aware that the main part of the heat starts at the far end of the finns away from the electrical connections.. so what i would do is set up the fan and heater so that the most of air volume is at the end with the most heat even if the electrical connections on the heater are on the oppisite side of the bradley then the  controll box / smoke generator

[Patience]

Here is my first draft of hook up.  I've added an element since the previous posts.  Say each element is 2400 Watts instead of what is listed, and I am running 10 guage wire from service panel to the fuse box listed above, then 10 guage wire to the bus bars, then 10 guage wire to the SSR and elements.  4800Watts/240volts = 20 amps which 10 guage wire can handle w/no problem.  Do I still need to fuse the elements with lower rating than 30 amps? 

Also, say from the bus bars to feed the PID  I only run 16 guage wire to feed the 110V PID with a fuse rated by the mfr. (0.1amp? or something small like that).  If the elements are cranked and pulling all 20 amps thru the 10 guage wire, what happens to the little 16 guage wire being fed off the bus bar w/black wire in the picture? Is this a concern? I guess I'm having a hard time understanding if something of very high amps is getting fed all that electricity, doesn't smaller things hooked to the same circuit get overloaded?? 

Thanks!

[beefmann]

Pat,

what you show in your schmatic looks good. One thing i  did notice in mine when i had it  configured like yours  the fan removed to much heat from the smoke generator. not letting the heater in the generator to get hot enough to allow it to generate the  smoke .What i  did was add in a 3 position switch to select on-off-on so we  would have "smoke, off  cook ". it is a  simple  mod ..both power  legs  to the  center of the switch... from one outside tab of the swith to the smoke generator and catycorner of the  switch to your pid / fan ( look for a double pole double throw) this  should work very  well  for you ( the switch will have  6 tabs 2 columbs of two the two hots attach .. one hot to each of the center tabs.. and the outside tabs on the swich would be the same as the center tab much like your  top bus bar with the black leads where you  have three on the  right .. you would have another  three on the left  side.. then you  should  have it setup)

another thing i did notice is that you  dont  have a thermocouple ( you just might ne be  showing  it ) just dont forget it.

as for  using 4800 watts it is my  opinion it is way to  much... im using  900 watts in a 4  rack and has more then pleanty of  reserve heat  to  do 25 lbs baby back ribs at 240' f though that  is about as high as i would  go. also has done 40 lbs of tri tip at  once  with a  cook temp of 210 for 20 hours with the  same  900 watt heater. as for a test  run I  have taken the tempture up to 400 and it  held it very well though it  took better   part  of 30 minutes to get it there ... not that  i would ever go that high but i know i have th capicity to

my operation is a 2 to 4 hour cold smoke ( I.E smoke generator rather then smoke and cook

[Patience]

Thanks for your input beefman.  The smoker I'm building is about 2 feet deep by 4 feet long and 5 feet high.  I would also like to use it for pseudo baking (i.e. upto max of 350 deg.) for doing several turkeys or something at once and not worrying about the meat load making the heat source struggle, especially outside in a Michigan winter.  I havn't ordered the elements yet.  After I insulate the stainless shell w/mineral wool (only 1.5 inch) I'm going to fire up two or three 1000W hotplates and take some initial readings for how it holds the heat.  If I can get an inside temp of 400+ and everything is ok as far as insulation and no hot spots on exposed metal I'm gonna go ahead and cover the whole thing in aluminum or something else thats cheap and start mounting the fuse box, electrical box and switches and all the rest.  I think I need two elements because of the length, to get even heat for each column of racks.  If I can get by with some smaller 1800W's that would be fine with me also.  Like you, most of my cook time for butts is only 225.  I just want the option to turn it up when I need to.

What about using 2400W elements (two) and putting a simple oven dial controller after the SSR.   Then I can simply turn the dial to 3/4's of the way, and let the PID think that is 100% of output.  It will act somewhat like a governer I guess.  I understand though, if that dial is moved, I will have to run the PID's auto calibration/calculation deal over again.  I'm stuck on 2400W because the style I found will fit perfecty on the floor of the smoker and they are not very expensive, and I figure the higher wattage might last longer if not run full tilt all the time.

My fan will be above and on the opposite side of the smoke generator (this after reading your experience with cooling the puck burner, thanks) and I was hoping a dimmer type switch would work to control fan speed.  Fast for the initial drying/resting, the cutting back for smoke, then faster again when the heat gets cranking.  I'm far from that stage though.

One last question, do I put the switches for the accessories between its supply and its fuse, or the fuse and the load?  Or doesn't it matter.

Thanks again for your input.

[beefmann]

Pat,

i dident relize it is going to be a big unit and you  wanted higher heat, then  you are  making all the  right  moves. I would still put in a  dual pole  double throw on-off-on to control the fan, cook and the smoke generator for when you  dont need it and keep the fan from robbing the heat fron the generator

you  are on the  right track and insulate your cooker as good as you  can,,

just to confirm your calculations on wattage you  mat  want to  check out this site for heat loads

http://www.heatershop.com/btu_calculator.htm

and good  luck with your project and your on your wat to having a good unit,,, when you  get  done would like to see pictures of it.


beefmann

[Patience]

Thanks Beefman.  Once I get rolling I will post pics.  Comparing avg. insulation to good insulation is a difference of almost double watts.  My best bet is to insulate, then get a few 1000W round coil hotplates that are dime a dozen, and see how many it takes to get to temp and how fast and then see how the unit holds the heat.  I can even have the guys at the local fire dept. bring their thermal camera over to see where the insulation is poorest.  I guess what makes a Bradley so efficient is the insulation job and door seal.

Thanks again for your input.

[beefmann]

welcome Pat sounds like you  have a good design and gave it a lot of thought... hope it gives you a lot of years of  smoking and cooking