Why won't this breaker trip ? Very Dangerous

Reply

  #1  
Old 10-02-06, 08:42 AM
Member
Thread Starter
Join Date: May 2006
Location: Sparta, NJ
Posts: 169
Why won't this breaker trip ? Very Dangerous

OK guys here is my situation that I discovered by accident. I was changing a light switch in a bathroom, the circuit was hot and I did not know wich breaker to turn off. So to kill the circuit I pulled the switch out from the metal box and used a screwdriver to short the circuit( I know VERY stupid) but to my suprise the breaker would not trip. The light flickered, sparks were flying but the power stayed on. The metal box is grounded. So to investigate further I remove the switch from the wires and touch the hot wire to a neutral in the box, same result. I tested every recepticale on this circuit with a plug in circuit tester, result was correct wiring on all receps according to the lamps on the tester. I changed the breaker thinking it was defective, same result.

Some more background:

House was built in 1964, 200 amp service panel 5 yrs old, Cutler Hammer breaker, 15 amp circuit, 14/2 NM w/ground, circuit serves 3 bedrooms and 2 bathrooms. The ground and neutral are tight in the service panel.
 
Sponsored Links
  #2  
Old 10-02-06, 09:02 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Shame on you for not knowing which breaker drives this circuit. You should have completely mapped your house within a short time of moving in. This information could save your life.

Either you have defective breakers or you have not found the correct panel.

Sort this mess out and then completely map out your electrical system. Your goal is to what is on each and every circuit breaker and which circuit breaker controls each and every receptacle, light or appliance in the house.

And never do something stupid like try to trip a circuit breaker or blow a gfuse by creating a short circuit. That is, unless you have a death wish.
 
  #3  
Old 10-02-06, 09:02 AM
itsunclebill's Avatar
Member
Join Date: Jan 2006
Location: Denver, CO area
Posts: 221
I'd suspect a bad breaker. But on the other hand a bad connection somewhere in the circuit may prevent the breaker from seeing enough current to fault.

In any event, a direct short should trip the main breaker if the branch breaker doesn't trip. This leads me back to a bad connection somewhere.

As to your method of tripping the breaker, let's just say it could have gotten you hurt.
 
  #4  
Old 10-02-06, 09:17 AM
Member
Thread Starter
Join Date: May 2006
Location: Sparta, NJ
Posts: 169
No doubt trying to short the circuit was stupid but I'm glad I did it in this instance. How else would I have detected this problem, is there a safe way to test for this ? I would not want my house to burn down because the breaker won't trip. I will check for a loose connection at every junction and replace the breaker with another one. If it is a bad connection would it most likely be a neutral or the ground ?
 
  #5  
Old 10-02-06, 09:40 AM
Member
Join Date: Oct 2005
Location: Milwaukee WI
Posts: 1,338
Now that you've been given 50 e-lashes ... how about some tips?

The proper procedure is to turn off breakers off and on one-by-one until the circuit in question goes out.

If no individual breaker does the trick then you turn off all the breakers one-by-one, again checking after each to see if the circuit is affected.

The reason for this is that sometimes downstream from the panel, somebody has erroneously wirenutted two separate circuits on the same bus together.

If that had no effect, then once all the breakers are off, shut off the main and see if that does the trick.

If that does not do anything either you have a bad main breaker or you have not found the right panel.

In the case of testing by shorting, it's already been made clear that that is a bad idea. While you might die doing this sort of thing, it's much more likely that you would be injured and cause permanent damage to your wiring.

So anyway, post back and let us know what's up. Just don't mention the things you already know you did wrong, unless you are a masochist.
 
  #6  
Old 10-02-06, 10:11 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
The average homeowner should not test his or her breakers. What should be done is that at least once per year the breakers should be turned off, the circuit checked for power, and the en the breaker should be tuened on again. Naturally if a breaker does not turn off it needs to be replaced. Arc-fault and GFCI breakers should be tested according to the manufacturers instructions, which usually states once per month.
 
  #7  
Old 10-02-06, 11:54 AM
Member
Thread Starter
Join Date: May 2006
Location: Sparta, NJ
Posts: 169
I know this circuit serves the entire top floor of the house wich is the 3 bedrooms and the 2 baths up there. With the breaker in question off nothing else in the house is without power, but I will double check that again. There is only 1 panel in the house, wich is 5 yrs old.
 
  #8  
Old 10-02-06, 01:29 PM
Member
Join Date: Jun 2002
Location: Brethren, Mi
Posts: 1,648
Has anyone checked to be sure this panel is correctly bonded??????????
 
  #9  
Old 10-02-06, 01:39 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Bonding, proper or improper, of the panel will not effect the breaker tripping properly.

I mean the above with regards to bonding of the panel to the the building plumbing, and to other metal.

Bonding of the neutral and the ground, if done improperly or missing, may prevent the breaker from tripping if the hot wire contacts the ground terminal. It will not prevent tripping if the trip is because of an overloaded circuit.

Is the house five years old, or is the panel five years old?

A five year old house will NOT have the entire upstairs on one circuit.

A five year old panel, in an older (much) house just might have the entire upstairs on one circuit.
 

Last edited by racraft; 10-02-06 at 06:30 PM.
  #10  
Old 10-02-06, 07:31 PM
Member
Join Date: Jun 2002
Location: Brethren, Mi
Posts: 1,648
If the neutral bond is missing it would not trip in the event of a short to ground, which sounds like what it was, it was just not considered in the other responses and I didnt go into details as I was busy at the moment. Whoops, I see he said he short circuit the neutral too.
 
  #11  
Old 10-03-06, 06:15 AM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
It sounds to me like this is a switch loop on the _neutral_ side of the light fixture.

If this _guess_ is correct, then the 'hot' side of the switch is connected to the lamp, with the other side of the lamp connected to the real 'hot' supply. Connecting this terminal to ground will complete the circuit back to the supply transformer, but it won't be a short circuit because it is going _through_ the lamp.

You would see sparks from the inrush current through the lamp, and the lamp would flicker, but the breaker would never trip.

You can test this by measuring the voltage from the switch terminal to ground, with the light switch both on and off. If you detect voltage with the lamp off, and it goes away when the lamp is on, you have a switched neutral. This is a safety issue that needs to be fixed.

-Jon
 
  #12  
Old 10-03-06, 07:04 AM
Member
Join Date: Jun 2006
Location: usa
Posts: 274
Thumbs down

Some of the older breakers are thermal trip type only, which means that they require heat (such as produced by a short circuit of a few seconds duration) to open. Newer models have thermal/magnetic trip which means that they will open instantaneously (by magnetic action) on a short circuit.
I once (accidently) cut (energized) cables completely in two before without the thermal trip breaker opening.
The short must last long enough for the thermal circuit in the breaker to get hot. This will (usually) happen before the conductor gets hot enough to damage the insulation on the wire.
The purpose of the breaker is to protect the wire, not you.
Find another way to check the circuit. Your way will put you in a hospital or a morgue.
steve
 
  #13  
Old 10-04-06, 04:53 AM
Member
Thread Starter
Join Date: May 2006
Location: Sparta, NJ
Posts: 169
The house is 42 yrs old, the original Bulldog Pushmatic box was replaced with a 200 amp Cutler Hammer 5 yrs ago by an electrician and was passed by the bldg inspector. There are 2 ground rods outside and a ground to the cold water pipe.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'