Sub-panel without separate neutral/ground bars.

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  #1  
Old 10-28-15, 11:42 AM
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Sub-panel without separate neutral/ground bars.

I've recently hooked up a 220v outlet from a sub-panel, using a triplex breaker to be able to hit both buses in the box. While doing so, I noticed that this sub-panel does not have separate ground/neutral bars, both are going to the same bar.

I have been trying to use a triac to control the power going to a heating element that I use for making beer, and the triac instantly blew out upon being plugged in. Everything appears to be hooked up correctly, so I'm wondering if the fact that the neutrals and grounds share the same bar could be the culprit.

For the record, I did not install this sub-panel, it was this way when we bought the house, despite having an electrical inspection and having some work done on both panels as a result of the inspection.

Any advice would be greatly appreciated.
 
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Old 10-28-15, 11:53 AM
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I'm wondering if the fact that the neutrals and grounds share the same bar could be the culprit.
No. What you have is grandfathered and electrically okay though just a bit less safe then modern code requires.

However unless you have three phase your description of how you connected it doesn't make sense.
using a triplex breaker to be able to hit both buses in the box.
It would be a double pole breaker. Triplex refers to a type of cable. In this case though you would use 2-conductor cable plus ground.

Nominal voltage is 240v not 220v. Is the triac rated for 240 volts? Show us a diagram or tell us how you connected the controller.
 
  #3  
Old 10-28-15, 11:55 AM
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Not sure why you used a triplex breaker instead of standard two pole, unless you didn't have room in the panel to add another two pole.

Having ground and neutral tied to together in a subpanel is a code violation and a safety issue, but is not a functional issue and should not have caused any problem with your circuit. Under all normal operating conditions, neutral and ground are at the same electrical potential, namely zero volts with respect to earth ground. The reason ground and neutral are only tied together in your main panel (or sometimes in the meter base, depending on local standards) is to avoid having any current flowing in the grounded conductors under normal conditions. This is primarily a safety consideration.

If you give us more information on your controller (perhaps a diagram) and what you are trying to do, we may be able to help identify the problem.
 
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Old 10-28-15, 12:56 PM
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Apologies, I used one of these breakers, and had been told it was called a triplex:

http://www.amazon.com/gp/product/B00...ilpage_o02_s00

I used 10/3 wire to the outlet, red and black to each side of the breaker, and the ground to the ground/neutral bar. This all tests out alright, 110 on each pole to the ground, 220 testing them together.

I used a 3-prong Leviton outlet, red/black to each of the live poles, and the ground as the 3rd.

I then used a 3-prong cord (obviously), wired to the SCR like this:

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The SCR is Chinese, and poorly documented, but widely used. It's one of these:

http://www.amazon.com/gp/product/B01...ilpage_o00_s00

So I have it grounded from the plug, with that same ground wire connected to the keggle so that it is grounded as well.

The red and black wires feed into the inputs on the SCR, and from the outputs they go straight out to the heating element on the keggle.

I must be missing something obvious here....

(I can't seem to delete the attached post, which is a diagram of how I had originally tried it, with only one pole going through the SCR. This didn't work at all.)
 

Last edited by ray2047; 10-28-15 at 01:26 PM.
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Old 10-28-15, 01:21 PM
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Apologies. I misread the Ebay info. It should be fine for your application.
 

Last edited by ray2047; 10-28-15 at 02:36 PM.
  #6  
Old 10-28-15, 01:38 PM
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Thanks for deleting the image, I'll remember that next time.

The 10/3 was what I had in the house, and being fairly broke at the moment, I merely capped off the white wire at both ends.

The element can draw up to 22.9 amps, according to this site, which has far more info than Camco's own site:

Heating Elements

I do know of lots of people who have used this same SCR controller with this element without issues, which is why I was assuming that I must have wired something wrong, but it sounds like maybe I haven't?
 
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Old 10-28-15, 02:41 PM
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Again apologies. I misread the specs for your controller. It should be fine for your use so I'm not sure what went wrong.
 

Last edited by ray2047; 10-28-15 at 05:30 PM.
  #8  
Old 10-28-15, 03:46 PM
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Nononono, you mean, "The problem is obvious, you just need to fix X.

I've blown two of these controllers now... Everything looks right, but it just doesn't work. Maybe I've got a short somewhere, or I'm misunderstanding how the controller is supposed to be wired. Today I got a loud POP and some smoke, which I would take to mean that I crossed wires somewhere. Would that happen if I had the black and red wires mixed going in/out of the SCR, or would it not care? I've done a lot of wiring with 120, 240 is new to me.

I guess I'd better either order one that actually comes with documentation, or build one myself with an SCR and a potentiometer.

Thanks for your time, I really do appreciate it.
 
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Old 10-28-15, 05:08 PM
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I'm having trouble deciding whether I don"t understand what I know, or I don't know what I understand.

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Or are my math skills lacking?
 
  #10  
Old 10-28-15, 05:23 PM
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Do the instructions identify the point on the SCR box you are connecting the ground wire to. It could be you are grounding part of the SCR control circuit. I will assume you have deciphered the chinese to determine which 2 terminal lugs are input and which 2 are output. The website for the controller contains a note the SCR output needs to be derated if the heat sinks on the SCR controller reach 80 degrees C. I would say this is not a well designed unit. Good luck.
 
  #11  
Old 10-28-15, 06:44 PM
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Looking at some of the other look-alike controllers at amazon, there was one with labels in English and it showed the left two terminals being line and right two being load. That jibes with how you hooked it up. red/black swap should make no difference.

When you first powered it up, did you have the heater element connected? Was the voltage knob turned up? resistive heating elements have lower resistance when cold and I suppose it's possible the inrush current is blowing the circuit, although it *should* be protected against that.

I would first hook up only the line side, make sure the voltage pot is all the way down, and power it up that way. If it doesn't blow, I'd advance the voltage setting with a meter connected to the output and see if it is working properly. If all that works, I'd connect the heater, but make sure the voltage was all the way down before powering up.....

Oh, one more thing...make sure your heater element isn't shorted to ground. Check resistance from each terminal to ground...should be infinite.

Good luck!
 
  #12  
Old 10-28-15, 06:45 PM
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This old man. Are Camco and Qunqi the same company? What part number do you have for the Qunci? Could be they are not equivalent devices?
 
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