DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Electrical and Wiring > Dual 20 Breaker Short




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Old 12-13-2011, 11:07 PM  
ChollaBob
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Default Dual 20 Breaker Short

A dual twenty breaker was off this morning which shut the well down. I replaced the breaker and instead of shutting off slow, the new breaker shut off fast. From the breaker, the heavy 600 V submersible yellow three wire (a 240 line) goes underground for a 100 yards to a well house where the line is hooked up to the water pump pressure switch. After replacing the Schneider D 30/50 switch (confirmed wiring by company tech), the breaker shut off with a flash.

So instead of thinking I have a bad pump or relay, I disconnected the line from the pressure switch, capped the three wires and turned on the breaker. It stayed on for a couple of hours and then shut off.

The ground is wet and muddy here as snow has started to melt. Does anyone have any idea on how to troubleshoot 100 yards of underground? Maybe I will unhook the wires at the box and see if its the new breaker! Pictures tomorrow and thanks for any help.



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Old 12-14-2011, 02:31 PM  
speedy petey
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It's NOT the breaker, nor was it the pressure switch.

You are throwing parts at this hoping something will work. That can be an expensive and frustrating way of troubleshooting.

You need someone to come out and megger the underground wires.



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Old 12-14-2011, 03:47 PM  
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To my knowledge, a dual breaker only feeds from one phase in the breaker box.
If you need a proper 240V circuit, you must feed the circuit from opposing phases in the box.
You will want to install a properly rated, full size, 2-pole breaker for this circuit.

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Old 12-14-2011, 06:31 PM  
speedy petey
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Quote:
Originally Posted by kok328 View Post
To my knowledge, a dual breaker only feeds from one phase in the breaker box.
What is a "dual" breaker?
Two pole?
Twin?

I am assuming since it was working he had the proper "dual" (two-pole) breaker in there. A twin breaker while not working will NOT trip just because it is wrong.
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Old 12-15-2011, 01:49 AM  
ChollaBob
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Attached is a picture from when I rewired the box: the 20 amp two pole is marked Well. Sorry for calling dual twenty! We have no water and having someone come out to megger the underground line is a good idea.

The fuse shut off with the underground line disconnected from the well house. Can I try the breaker alone or will the load on the breaker with no wires throw it anyway? This new breaker flips quick a couple of times before setting. When hooked up to the well house, the breaker throws a spark while shutting off immediately after turning on.

If a short is identified by a megger, can they locate the break in the underground line or does the line have to be replaced?

I replaced the breaker as this box is in bad condition and the house breaker had burnt out causing a major electric problem in the house. The pressure switch was from 1980 with corrosion so took the opportunity to upgrade. Thanks!

Well fuse runs two black and white 120 wires to the conduit where it is wired into the yellow underground line. Thinking now maybe there is a loose connection at the splice as never have seen this splice. As the ground is very wet, this could be the short if the connection is in the ground below the box - would not be surprised from what I've fixed here so far!

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Old 12-15-2011, 04:36 AM  
speedy petey
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OK, well that explains a lot more. The breaker and switch made sense then as well.

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Old 12-15-2011, 03:49 PM  
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The submersible cable runs under the ground 3 inches! Travels under the trailer and must splice into the new yellow submersible at some point between the pole and the well house. I am suspecting this ancient cable, the splice, and the wet ground is the problem. Called an electrician to do a megger but I bet I am going to have to dig up this cable and replace anyway. This place is the way out on the plains so no surprise finding this. What is the general code for underground cable? Four feet?

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Old 12-15-2011, 05:32 PM  
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I was thrown by the phrase "dual twenty breaker". I pictured it to be one of those space saver breakers where two circuits occupy on breaker or otherwise correct terminology is (Tandem Breakers).
From the pics, your setup is correct (what I refer to as a 2-pole breaker).
A draw back of online troubleshooting.

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Old 12-17-2011, 08:51 AM  
ChollaBob
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I had an electrician out yesterday to review everything and he found no short in the underground line. After reconnecting the water pump pressure switch, the water came back. He suggested to replace the fast 2-pole 20 amp breaker with a 30 amp 2-pole.

Last night the 2-pole 20 breaker switched off. I had to flip the breaker three times before it stayed on, and it has been of for two hours now. I am putting in a fast 2-pole 30 amp tomorrow. I had replaced the slow acting 2-pole 20 with a fast 2-pole 20 last week with the first shutdown. The electrician suggested that one exposed water line had frozen and originally threw the breaker.

The unknown factor is that both of us had found continuity with the multimeter audio continuity function with all motor wires at the Franklin pump relay box. I had measured 11.5 to 15 resistance in the motor, which seems to be right. I had told the electrician that I was starting to test the relay box itself for a short. After that, he threw the fast 2-pole 20 amp breaker and everything ran.

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Old 12-18-2011, 10:34 AM  
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I believe it is the cable. Right now the ground freeze is melting and saturated wet: I can't keep the breaker on, but it stayed on last night for a few hours with the ground frozen. The new breaker shut off with the line disconnected. I am planning on digging the 60 foot trench, laying in plastic conduit, and adding an extra line to keep the well house from freezing with heat tape and a lamp. If this does not solve the problem, then it's still progress as I won't be replacing frozen pipes like last winter. Presently, the cable runs for two inches under ground for the ten feet I have dug up, in the wrong direction. There is an underground splice somewhere. I want to upgrade this.

How deep should the trench be? Use 10 gauge wire?

I will get the motor amperage today and buying a Harbor Freight amp meter tomorrow. For four years, the pump ran without throwing the breaker once. I think this cable short is intermittent: a short that comes and goes with ground conditions. Thanks!



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