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Old 11-07-2012, 06:00 PM   #31
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All voltage measurements good until load is put on the circuit


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You may want to talk the owner into driving a ground rod near the panel and running a number 6 copper wire into the panel. Or to the existing water pipe ground. Mostly for lightning protection.
I'll see what I can do, thx.

The electrical contractor didn't correct something that I thought he would... the jumper wires from the main panel to the subpanel for the stove circuit (50A breaker), are #8 copper, stranded. Can anti-oxidant be used on these connections, or should the wires just be replaced with Aluminum. Gotta feeling the correct answer is "replacement" but I'll ask anyway. Hope I'm not wearing out my welcome.

The contractor mentioned it to the owner, but then didn't do anything about it. Don't know why.

How long would it take for the AL/CU connections to cause a problem (contractor said it would cause a hot spot)? The box is less than four years old I'm pretty sure (from talking with the resident) and the copper wires look new.


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Old 11-08-2012, 08:25 AM   #32
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All voltage measurements good until load is put on the circuit


The number 8 copper is fine. No anti oxidant is needed on copper. Copper is better than aluminum, aluminum is cheaper than copper. So there is no need to bother with those.

You mention al/cu connections. Do you have copper to aluminum splices? I'm confused by this.
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Old 11-08-2012, 09:19 AM   #33
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All voltage measurements good until load is put on the circuit


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The number 8 copper is fine. No anti oxidant is needed on copper. Copper is better than aluminum, aluminum is cheaper than copper. So there is no need to bother with those.

You mention al/cu connections. Do you have copper to aluminum splices? I'm confused by this.
The hot bus bars in the main panel are aluminum (I'm assuming because they look to be aluminum, if that means anything, and the electrical contractor called them al to cu connections), and the jumpers to the aluminum subpanel are stranded copper. My splices are al to al.

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Old 11-08-2012, 11:12 AM   #34
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All voltage measurements good until load is put on the circuit


AL/CU means the terminals are rated for either copper or aluminum. The "jumpers" (not quite sure what you mean by that) are connected to the lugs or terminal connectors right? In a terminal or lug with a screw tightened down on the wire? A picture might help.
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Old 11-08-2012, 06:24 PM   #35
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All voltage measurements good until load is put on the circuit


No way to do a pic at the moment - can't get it from my phone to PC and digicam died.

What I meant by jumpers was the #8 stranded copper from the main panel to the subpanel. Those jumpers are stuffed in the holes (lugs?) with the large diameter AL wires and the screw tightens down on them both, jamming them together. The large diameter AL wires are also stranded. Not sure about the subpanel and its connections type.

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AL/CU means the terminals are rated for either copper or aluminum.
I mis-spoke here - the contractor identified (to the owner while they were both standing at the panel) that the copper jumpers were a problem (said it would create a hot spot), but I'm pretty sure he didn't change the jumpers to AL. Will have to go back and check to be sure. If this is an AL (only) panel and not rated for either AL or CU, can you guesstimate how long it might take to create a problem?

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Old 11-09-2012, 08:23 AM   #36
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All voltage measurements good until load is put on the circuit


Okay, I understand. Yes that is a problem and for more than one reason. First only one conductor can be in a terminal like you are describing. Second copper and aluminum can cause corrosion when touching each other as you describe. How long before it becomes a problem depends on how much moisture is present. It might be months, it might be years.

The biggest problem is the #8 wires are not protected against overload, they are connected to the incoming larger conductors.

The number 8 wires should be connected to a 50 amp circuit breaker in the main panel. And to their own proper neutral and ground terminal. To make space in the main panel, two circuits can be moved to the sub panel.
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Old 11-10-2012, 11:53 AM   #37
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All voltage measurements good until load is put on the circuit


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The biggest problem is the #8 wires are not protected against overload, they are connected to the incoming larger conductors.

The number 8 wires should be connected to a 50 amp circuit breaker in the main panel. And to their own proper neutral and ground terminal. To make space in the main panel, two circuits can be moved to the sub panel.
The electrical contractor is going to be changing this main panel, because it has no main circuit breaker in it. I'm going to passing this on to him - maybe he already has it in mind to correct this situation.

Thanks so much for all your help.
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Old 11-10-2012, 04:31 PM   #38
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All voltage measurements good until load is put on the circuit


That sounds good. Hopefully he will fix this issue also.
You're welcome. I'm happy I could help.

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