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SSR to heating element wire HOT?

post #1 of 12
Thread Starter 
I am building a 1950 IH fridge smoker with PID and SSR control... I've searched for hours but have yet to find any suggestions on which type of wire to use from the SSR to the heating element.

My smoker is 90% complete but I am worried that the wire that I used to go from my SSR to the element may be incorrect.. I started it up last night to do a functions check of the heating system and noticed that the wires going to the heating element were very hot to the touch after 5 minutes...

I wired the SSR to the 1500 watt elements with high temp paired 12 gauge wire that is used on aircraft and is stable up to 1000 degrees F..

Everything else on my build is working great but I am hesitant to let the smoker run for very long and risk frying some of the electronics....

I've followed this forum ever since I started thinking about my smoker build when was deployed to Iraq and want to personally thank everyone here for all the suggestions and knowledge!

Control Box with with timer, circuit breaker, PID, rotary knobs to turn off or adjust each burner for even heat, SSR, external outlet and 4 temperature gauges for meat probes:


Just have to grind off excess high temp silicone then add a door gasket and door latches then its off to get its coat of LINE-X!!!
post #2 of 12

Looks cool,  Are you running both off one 120 volt 20 amp line or are you  using 240v. You could replace the 12G with 10G. 

 

Stan

post #3 of 12
I used 12g wire from SSR to element (actually I bought a 12g 3 wire pig tail), I haven't noticed it getting hot at all? Of course, I only have 1 1,500w element?

3,000w sounds like a lot for a 120v? I have a 220v 5,000w smoker as well, it doesn't get hot at all either and it's 10g?

I would say that's your culprit?

~Brett
post #4 of 12
Thread Starter 
1500 watt combined @ 110v. Sorry I should have added that. My supply line for the control box does not get warm @ all... I still don't understand how wire rated to 1000 F would be getting hot @ all...
post #5 of 12
Thread Starter 
1500 watt combined @ 110v. Sorry I should have added that. My supply line for the control box does not get warm @ all... I still don't understand how wire rated to 1000 F would be getting hot @ all...
post #6 of 12

Just kinda thinking about your build here, if you have those heating elements wired in parallel, you will be drawing approximately 25 amps.  That is a bit high for 12ga COPPER wire.  It really should be 10ga copper.  If that is aircraft wire, would it happen to be aluminum?  I know weight is a huge issue on aircraft and copper would add, literally, a ton of weight.  I would change out to 10ga copper, with a hi-temp jacket.  Are you plugging this into a 120 Volt, 30 Amp circuit?  If you could, post a wiring diagram.  I would like to analyze it.

post #7 of 12
The heat is not generated by the smoker elements as direct heat, rather by the resistance in the wire against the amperage...just like all things that create "friction" there's heat involved, electricity is no different. resistance = friction = heat, if it's rated to 1,000* it will most likely be fine, but the SSR will fry if subjected to that amount of heat for prolonged times. also, aluminum has more resistance (all things being equal) than copper so that will add to the heat issue.

I would either change out the wiring or only use one element until you can?

~Brett

P.S. that's one nice looking smoker/panel control with PID!
post #8 of 12

If anybody read the long post I made before editing this..... Ignore it

 

Most important question:

 

Did you wire the two 1,500 watt elements in SERIES or PARALLEL?  It makes a difference.  One way both elements are getting 110v and will "try" to output the 1,500 watts they are rated for.  The other way you are only going to output about 1/4 the rated power (ie, heat) out of them due to ohms law.

 

Other issues flow from there, but this question needs to be answered first.

 

(HINT:  In SERIES you add the resistances, therefore dropping the current across each element by half. In PARALLEL you double the current draw and therefore double the power for the full 3,000 watt output.  I suspect it's in Parallel if you are getting wire heating as 3,000 watts is too much for any "standard" household 110v circuit but answer my question first before I go down that road.)

 

PS - also is that electrical wire copper or aluminum, and what is the voltage rating marked on the wire outer sheath?


Edited by dward51 - 5/11/13 at 2:01pm
post #9 of 12
Thread Starter 
Dward, yes they are wired in parallel... guess I should have done some simple math. To the best of my knowledge it is wired exactly the same as it was as a hot plate from amazon. The only difference is that I added a PID and SSR before the original rheostats. The wiring is also aluminum which I didnt expect to make that that much of a difference but I suppose every little bit counts especially in a heating application. I will be gone all weekend but I will try running just one burner and see if I still have the same issue.

I am still interested to see what type of wire everyone else uses? Not so much size but style.
post #10 of 12
Quote:
Originally Posted by smokinkarl View Post

Dward, yes they are wired in parallel... guess I should have done some simple math. To the best of my knowledge it is wired exactly the same as it was as a hot plate from amazon. The only difference is that I added a PID and SSR before the original rheostats. The wiring is also aluminum which I didnt expect to make that that much of a difference but I suppose every little bit counts especially in a heating application. I will be gone all weekend but I will try running just one burner and see if I still have the same issue.

I am still interested to see what type of wire everyone else uses? Not so much size but style.


Ok,  a few observations, suggestions and options.....

 

Aluminum "aircraft" cable may very well not be rated for 110/220v service (voltage rating of your particular cable should be marked on the outside sheath of the wire).  If it's not rated for 110v or 220v, it needs to be replaced (and if it's only rated at 110v, it may still have to go depending on where you go from here).  Also aluminum electrical cable should be de-rated for the amperage capacity as compared to copper electrical cable, by using the next higher gauge of aluminum wiring.  So 12 gauge aluminum wire is generally going to be capable of carrying the same number of amps as 14 gauge copper.  To get the same capacity as 12 gauge copper, you are looking at using 10 gauge aluminum.  The other issue with aluminum electrical wiring is oxidation. Over time, unless some oxygen shielding compound is used at the connections, the aluminum wire will oxidize and the increased resistance at the junction can cause a fire (this is the primary reason houses are no longer wired with aluminum wire).

 

As to the heating elements....

 

3,000 watts is going to draw over 27 amps at 110v (not including any power for the other components in the smoker such as PID, fans, etc...).  The average household outlet is wired on a 15 amp breaker with 14 gauge wire and occasionally you will find a 20 amp household circuit.  Either way, 3,000 watts load is going to overload a standard residential circuit.  You do occasionally see 30 amp residential circuits used for RV connections, but those have 10 gauge copper wire and a special outlet/plug is used. 

 

Options......

 

There are quite a lot of similar sized electric smokers people have made and posted about on this forum which use a single 1,500 watt element and work just fine.  I would try disconnecting one of your elements from the circuit and see how the cabinet performs with a single 1,500 watt element.  You may be perfectly happy and problem solved.

 

If you want to keep the cabinet running on 3,000 watts, your next choice involves rewiring the outlet you are powering the smoker from to either a 30 amp 110v circuit (30 amp breaker and at least 10 gauge copper wire for entire circuit run) *OR* running a 220v circuit to where the smoker will be used.  A 20 amp 220v circuit should be plenty and you could use 12 gauge copper wire for the run.

 

If you go with the 30 amp 110v option, just upgrade your wire in the smoker to handle the 27.7 amp resistive load and I think you are done.  

 

If you go with the 220v option you need to add a second SSR and do a little re-routing of the wiring inside the smoker.  For the sake of discussion let's assume you have already had a 20amp 220v outlet installed where the smoker will be used.  You can then break the 220v into the two independent 110v legs inside the smoker.  Instead of wiring each leg together as a single 220v circuit, they can be split into two 110v circuits using a common neutral.  Use each independent 110v leg to power one 1,500 watt heating element.  Other than a little re-wiring and the possible addition of a terminal strip to split the 220v into the two 110v legs, the only other somewhat major change is adding a 2nd SSR so each heating element is totally independent of the other.  You can still use the PID setup like it is as you can trigger the SSR's in parallel from the PID.  You could also add a on/off switch to interrupt the triggering signal to one of the SSR's letting you run only one element if you are going to do a low temp smoke (say the low 100's for sausage making).

 

If it was me and I wanted to stay with the full 3,000 watts I would go with the 220v option. But try running one element alone first.

post #11 of 12
Quote:
Originally Posted by dward51 View Post


Ok,  a few observations, suggestions and options.....

Aluminum "aircraft" cable may very well not be rated for 110/220v service (voltage rating of your particular cable should be marked on the outside sheath of the wire).  If it's not rated for 110v or 220v, it needs to be replaced (and if it's only rated at 110v, it may still have to go depending on where you go from here).  Also aluminum electrical cable should be de-rated for the amperage capacity as compared to copper electrical cable, by using the next higher gauge of aluminum wiring.  So 12 gauge aluminum wire is generally going to be capable of carrying the same number of amps as 14 gauge copper.  To get the same capacity as 12 gauge copper, you are looking at using 10 gauge aluminum.  The other issue with aluminum electrical wiring is oxidation. Over time, unless some oxygen shielding compound is used at the connections, the aluminum wire will oxidize and the increased resistance at the junction can cause a fire (this is the primary reason houses are no longer wired with aluminum wire).

As to the heating elements....

3,000 watts is going to draw over 27 amps at 110v (not including any power for the other components in the smoker such as PID, fans, etc...).  The average household outlet is wired on a 15 amp breaker with 14 gauge wire and occasionally you will find a 20 amp household circuit.  Either way, 3,000 watts load is going to overload a standard residential circuit.  You do occasionally see 30 amp residential circuits used for RV connections, but those have 10 gauge copper wire and a special outlet/plug is used. 

Options......

There are quite a lot of similar sized electric smokers people have made and posted about on this forum which use a single 1,500 watt element and work just fine.  I would try disconnecting one of your elements from the circuit and see how the cabinet performs with a single 1,500 watt element.  You may be perfectly happy and problem solved.

If you want to keep the cabinet running on 3,000 watts, your next choice involves rewiring the outlet you are powering the smoker from to either a 30 amp 110v circuit (30 amp breaker and at least 10 gauge copper wire for entire circuit run) *OR* running a 220v circuit to where the smoker will be used.  A 20 amp 220v circuit should be plenty and you could use 12 gauge copper wire for the run.

If you go with the 30 amp 110v option, just upgrade your wire in the smoker to handle the 27.7 amp resistive load and I think you are done.  

If you go with the 220v option you need to add a second SSR and do a little re-routing of the wiring inside the smoker.  For the sake of discussion let's assume you have already had a 20amp 220v outlet installed where the smoker will be used.  You can then break the 220v into the two independent 110v legs inside the smoker.  Instead of wiring each leg together as a single 220v circuit, they can be split into two 110v circuits using a common neutral.  Use each independent 110v leg to power one 1,500 watt heating element.  Other than a little re-wiring and the possible addition of a terminal strip to split the 220v into the two 110v legs, the only other somewhat major change is adding a 2nd SSR so each heating element is totally independent of the other.  You can still use the PID setup like it is as you can trigger the SSR's in parallel from the PID.  You could also add a on/off switch to interrupt the triggering signal to one of the SSR's letting you run only one element if you are going to do a low temp smoke (say the low 100's for sausage making).

If it was me and I wanted to stay with the full 3,000 watts I would go with the 220v option. But try running one element alone first.

Dave, I was hoping you'd chime in!!! @Karl, If you listen to Dave (dward51) you will get not only a great advice, but a free education in the world of PID's, SSR's and general electric knowledge, while they often say you get what you pay for, I can tell you from chatting with Dave previously, his is knowledge and advice are worth at least a every penny spent on your smoker!!!

Glad too see you in good hands!

~Brett
post #12 of 12
Thread Starter 
Must have not stated the burner application clearly... 750 Watts per burner for a combined total of 1500 Watts which should put me at 12.5 amps roughly. Of course that is not including any other electronics wired in. I am suspecting that the issue lies within the wiring from the SSR to the burners. I have ordered some high temp oven wire from amazon http://www.amazon.com/gp/product/B001ALK97C/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

My original question which seems to be missed by everyone was what type of wire is everyone else using?

Burners I am using
http://www.amazon.com/Continental-Electric-CE23319-Double-Burner/dp/B001BC7IWY/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1368416321&sr=1-1
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