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Old 03-26-2011, 04:22 AM   #11
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Yeah without some real information about all the involved devices, I think your tag line speaks worlds ... I would love to recommend that he meter the potentials between the different grounds and neutrals to ensure no ground loops/floating grounds/improperly bonded neutrals; but, it would not reveal anything with a complete picture of the circuit from the mains panel to his rig.



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Old 03-27-2011, 12:55 AM   #12
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I'm wondering the same as Walker, where's the neutral wire on the 240v? You said the neutral and ground were tied together on the 240v. Did you splice them all together inside your control panel? If so, I'd agree, that's probably your problem. If you aren't using the neutral on the 240v for anything, just put a marrett on it and don't use it. The only time the neutral and ground should ever be together is in your main panel where the power comes into the house. Anywhere else and it "can" be dangerous.

If that's not your issue...

On your schematic, you show the element having a neutral. Is this correct? Most (by most I mean I've never seen one with a neutral) straight up heat elements don't have one. If it does, it can't be hooked up onto the neutral bus. It would have to be hooked up to a separate neutral with the 240v line (not connected with the neutral from your 120v line at all).

Hope this helps.

I haven't done any brewing with electrical rigs, but I am an electrician... If I missed what your saying or can help out in any other way, let me know.



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Old 03-27-2011, 03:47 AM   #13
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Exactly Wberry, can't agree more.

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Old 03-27-2011, 06:22 PM   #14
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I did not splice together the 240v ground and neutral, the outlet that I have available is a 3-wire NEMA 10-30R, so by spliced together I was referring to my understanding that in this older system, the ground and neutral are wired together as the same wire (this is the green wire coming out of my 240v inlet). This is the reason that I have a separate 120v inlet and what I think may be causing the issue (at least one of the factors at least) because I am running this combined wire to the ground post in my control panel where the 120v inlet and receptacles are also grounded.

As far as the element is concerned, there is no neutral running to it. I have a neutral wire from the neutral bus (from the 120v) and a hot line from its respective bus through the 2 pos NO switch that both run to the 120v coils of the 240v 40A element contactor. The load side of the contactor is then supplied by one hot line directly from the inlet and the other hot line runs from the inlet through the SSR driven by the PID then to the contactor.

I don't know if this clarifies anything, but let me know if you can glean anything from it. I am going to fiddle with it some today based on your suggestions, and if I can't get it still I will try to post some more detalied info

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Old 03-27-2011, 07:53 PM   #15
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You have a neutral from your 120 distribution block going to the coil for the 220, I don't think that is kosher.

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Old 03-27-2011, 08:50 PM   #16
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How else would I get a neutral line to the coil? The contactor itself is rated to 240v, but the coil to power it is 120v

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Old 03-27-2011, 08:59 PM   #17
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Haha, my bad. I took the ground coming off the element in your diagram as a neutral. I guess I've got a worse cold than I thought. Let's try again. Powering the 240v coil from a separate source (the 120v line) is fine, so that shouldn't be an issue. If I'm understanding you right, you can start the control circuit up fine, so the 120v contact pulls in and stays in, and the power light is on right? But then when you flip/push the element switch, that's when both GFCI's trip?

If I understand this correctly, have you double checked the wiring to make sure that the 120v line and neutral don't connect anywhere? Especially the connection points on the 240v relay. It's easy to get them mixed up. If all the connections are good. Try turning off the 240v circuit, and then try turning everything (including the element) on. Yes, the element won't actually turn on, but the 240v contact should still pull in. Then try it the other way around (only if you feel comfortable working live!!!) Turn off the 120v circuit and turn on the 240v. You will have to manually push in the contacts on the 240v coil. See if the 240v gfci trips. Let me know what happens.

Work safe! Make sure you wear safety glasses when doing this! I'm not trying to talk down to you at all, but it only takes a quick slip and a 30a 240v explosion can blind you! Seriously, if you don't feel comfortable pushing in the coil, don't do it. There's other ways we can troubleshoot it. You might be perfectly fine doing it and that's great, but I don't want to give advice that gets somebody hurt, you know what I mean?

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Old 03-27-2011, 09:38 PM   #18
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Ok, so I went with me gut reaction first when I went to figure it out and tried firing everything up after removing the ground/neutral line from the 240v inlet from the mutual ground screw in the panel and sure enough, everything fired up without an issue! Now my issue is what to do with that extra line in my panel, and how to go about grounding the inlet safely yet separately; any ideas?

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Old 03-27-2011, 10:44 PM   #19
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My 2 cents would be to simply cap the ground/neutral from the 240V and ensure that the ground from the 120V service is beefy enough to handle the amperage of a ground out of all the supplied amperage (both the 240 & 120 circuits).

IN THEORY - if your element went bad you would case ground to your rig and the only available path would be back through the 120V ground. Coming out of the industrial automation world ... I am paranoid about grounding on multiple levels. I would highly suggest ensuring that your WHOLE rig has a great ground of solid not stranded copper bonding everything - don't necessarily trust bolted and hinged connections to be current carrying capable. Great resources are looking at local code specs for hot tubs and above ground pools.

One last consideration, overall, is isolating the ground for your PID controller. To assist in lowering erroneous PID compensation, thus wearing our your element and amplifier, you will want your controller to have access to both a current ground and signal ground ... current grounds want to be solid/low stranded copper and signal grounds want to be highly stranded for more surface area.

Examples of this are as follows: Sensors, pump drives/amplifier control circuits, valve feedback and controller cards want signal grounds so they they share a common ground potential/reference. Items like pumps, heaters, frames, cases, panels all want current grounds rated for the max potential that can develop at that point in the system. The problem I see often in the threads posted here and other forums about people having a hard time tuning their control cards is a lack of understanding of types of grounds and what they are used for. Integrated electronics need a different approach then raw consumption devices - pumps, fans, etc.

Back to your problem though - I would meter the ground/neutral from your 240V supply to a KNOWN properly wired outlet in your house - using continuity on your meter to see if it is really a ground or a neutral. Please report back so that we can make a better recommendation and ensure you are safely wired. Unfortunately, electricity and proper wiring approach for projects like this are very dependent on how your house is wired. Let us know!

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Old 03-27-2011, 11:05 PM   #20
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How would he go about grounding a PID that does not have a ground? Not sure what OP is using but for example Auber PID that I have does not have a ground terminal and the case is plastic.



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