Breaker trips on fixture upgrade

[Chris Barnett]

Had five fluorescent 4ft fluorescent tube (bulb) fixtures each having two tubes controlled by a single wall switch. I rewired and added a single switch to four of the fixtures to enable usused lamps to be turned off, and the one remaining fixture (over the workbench) would be controlled only by the existing wall switch. After the change, the circuit breaker trips instantly when switched on.

I have checked the resistance of each circuit and find three, having new transformers not requiring starters and connected with 12 ga wire, are 12 ohms and two older fixtures having ballasts requiring starters and connected with 14 gauge wire, have 20 ohms. The bulbs are a combination of the standard and the power economy type. All fixtures are connected in parallel, two from one breakout box and the remainder from a second box.

Is there a special requirement for connecting the old and the new fluorescent lamps and is the reisistance unusually low for the circuits? I have rewired several times and still come up with the same answer...breaker trips. I miss my shop and want to get back to doing stuff but obviously, with a few temporary drop lamps, cannot really do much.

[Ken Fitzgerald]

Chris,

Do you still have the fixtures wired so that the wall switch controls one light and the other 4 are on a separate switch?

If so do this:

1. Turn off both switches and reset the breaker. Does the breaker trip?

If so you have a wiring problem between the breaker and the two switches.

If the previous test works, do this:

2. Turn on the origninal wall switch. Does the breaker trip? If so the problem is either (a) a wiring problem between the switch and the fixture or that single fixture.

If that works fine, do this:

3. Turn off the original wall switch and turn on the newly installed switch. If the breaker trips now, the problem is either (a) a wiring problem between the newly installed switch and the 4 fixtures it controls or (b) one of the 4 fixtures is bad. Disconnect them one at a time to eliminate them.


One more thing. The way I would wire in this new switch. I would pigtail the incoming power to the original switch to the new switch. Thus when working properly, you could either turn on 4 fixtures or 1 fixture independently.

Good luck.

[Dave Gaul]

Chris,

Last year when I wired my shop, I was so excited to turn that breaker on that fed my sub-panel to the shop... but as soon as I did, little bugger tripped immediately!!! I spent the following hour or so narrowing down the problem... turned out to be at one of the junction boxes (i used metal ones)... where a wire came into the box, I clamped the bracket down too tighlty and pierced the wire down to bare copper... botta boom botta bing, instant ground!!

Maybe check for something similiar?

[Chris Barnett]

Ken, Dave
Not sure but here is simple diagram of my install. I will comment that initially all worked but I noticed that I had not installed a cover plate on a junction box, so when I pushed one full wire nut deep back into the box, one light flickered :eek:. That is not supposed to happen (might have just been a bad starter, but I'm afraid of [respect] electric) , so I backed up and started to investigate....and everything went in a handbasket.

Dave's comment might be the ticket though...I'm an ME, ....so, if it has a threaded connection, is should be tight...right! I will disconnect all connections and remove cables from the junction boxes and inspect for damage. A meter might be faster but think I can be effective in spotting a cut in the insulation.

Have heard horror stories about the new improved fluorescent lamps so thought I best ask if they can be mixed with the antique ballasts (these fixtures were bought as salvage during preparations for '82 World's [Energy Expo] Fair)...whitest white porcelain coated shades...now that's quality. My lights ...might not work but they sure are pretty :D.

Thanks for the help. Will go check it out now...and watch for smoke.

[Dave Gaul]

If you wired as in your schematic, it should be fine AFAICT.

I'd be looking for that ground/short!

[Ken Fitzgerald]

I'll argue that one Dave...the breaker should be in series with the switches not parallel.

[Jerome Stanek]

if I am seeing this right you are shorting out the circuit.

[Jim O'Dell]

I have one circuit in my shop that I wired where I can have just the bench light on, or all lights on that side of the shop.
From the breaker: White neutral to white input of first light fixture, Black hot wire to input of switch, output of switch to black input at fixture. Pig tail white at first fixture to white at second fixture, pig tail black at first fixture to second switch input, output to black input at second fixture. Then black to black and white to white on the rest of the fixtures to be controlled by that switch. This way with second switch off, and first switch on, only light at bench comes on. With both switches on, all lights (for me on that side of the shop) come on. Switch 1 off, all lights off, no matter what position switch 2 is in. I actually put switch #2 in the ceiling which is low enough I don't even have to tiptoe to reach it. It won't matter what kind of fixtures you have or how old they are, as long as they are in working order.
Disclaimer: I'm not an electrician, don't play one on TV or the internet, and I have never stayed at a Holiday Inn Express. :D Jim.

[Chris Barnett]

OK, now I'm confused, some yeahs and some nays.

The breaker, on the left, has white and black connections, assume black on top and white on the bottom of diagram, which is connected to the right hand side in series. The black goes to the switch, which in reality connects in a wire nut to white, then to the switch, then on the other side of the switch where it changes to black, back to the lamp. Thus the switches are each series connected to the load, and the removed switch was series connected to all loads, with four switchable out of the overall circuit. With the wall switch re-connected, I could turn off all the lights, or switched on, the shop bench light is always on, and the other lights can be individualy switched on. [maybe I see the question....the dotted lines to the removed switch show only where in is placed in line...not actual wire paths). I cannot see a fault in the design but again, I am not an EE.

Did not have the umpff to do any inspections today...but in the morning or late tonight if conditions permit, will check out the obvious....which would not show as a short since the circuit in a transformer arrangement is a closed path.

Thanks for the help. Now, if I cannot find a short to a breakout box....will need to call a shaman....beware the Ides of July.

[Dave MacArthur]

not sure why you list the resistance/ohms of the lights? This is purely an over-current, too many amps issue. I'd think a basic trouble shooting tree would be this:
1. Add up the amps of all the lights when turned on and tripping the breaker. If the total circuit amperage is > breaker, problem found.
2. If amps for circuit < breaker amps, then either you are leaking current somewhere (short, poked through your insulation somewhere, one of the light units is bad/shorted), OR your circuit breaker is bad. Next logic step, test to see which...
2A. Replace circuit breaker with another one known to be good. Test. If it trips, breaker good, current leak bad. Find current leak.
2B. Hook up ammeter near panel and see what amps are flowing, if it flows long enough to register before CB trips.
2C. Disconnect furthest fixture, turn on, check. Work? Problem found, find leak in that fixture. CB trip? Move to next fixture...

Good luck!

[Dave Gaul]

I'll argue that one Dave...the breaker should be in series with the switches not parallel.


I do not see why the switches can't be where they are if he wants individual switches for L1-L4.

How else can you wire a switch to control each load independanlty of the others in the circuit?

As I see it, each switch has to be in series with the load that it is controlling...

[Ken Fitzgerald]

The circuit breaker Dave in that drawing is paralleled to the load....shorting across it.

[Rick Prosser]

The circuit breaker Dave in that drawing is paralleled to the load....shorting across it.

Yeah - Ken is correct, the drawing is incorrect. It (110) is more normally shown as:
155256

[Dave Gaul]

The circuit breaker Dave in that drawing is paralleled to the load....shorting across it.


Oh ok... got it!!! Honestly, I didn't pay much attention to the way he drew the breaker... I was focusing on the switches & loads...

Now I see your point Ken... and Rick made it more clear by re-drawing...

[Roger Frazee]

OK, now I'm confused, some yeahs and some nays.

The breaker, on the left, has white and black connections, assume black on top and white on the bottom of diagram, which is connected to the right hand side in series. The black goes to the switch, which in reality connects in a wire nut to white, then to the switch, then on the other side of the switch where it changes to black, back to the lamp. Thus the switches are each series connected to the load, and the removed switch was series connected to all loads, with four switchable out of the overall circuit. With the wall switch re-connected, I could turn off all the lights, or switched on, the shop bench light is always on, and the other lights can be individualy switched on. [maybe I see the question....the dotted lines to the removed switch show only where in is placed in line...not actual wire paths). I cannot see a fault in the design but again, I am not an EE.

Did not have the umpff to do any inspections today...but in the morning or late tonight if conditions permit, will check out the obvious....which would not show as a short since the circuit in a transformer arrangement is a closed path.

Thanks for the help. Now, if I cannot find a short to a breakout box....will need to call a shaman....beware the Ides of July.

Chris

First your drawing does show the breaker in parallel with the circuit. The white (grounded leg of a 120 volt circuit) never connects to the circuit breaker so the drawing is not correct as such... but your problem is a wiring error somewhere.

My understanding is you want to be able to turn the far right light on/off with one switch and be able to control the other 4 with individual switches. So instead of trying to troubleshoot what you have done I'm going to put up a drawing of how you would wire the circuit. Of course I cannot see what your wiring configuration is but a correct drawing should help solve the problem. I suspect you have wired in a direct short to the grounded leg of the circuit.

One thing you mentioned that puts up a possible red flag is connecting to a white wire with a black wire. This can be correct if wiring switch legs from the fixtures themselves where both white and black are used as switched hot and constant hot.

Anyway here is a drawing of one way to do what you want. I'm only showing 3 lights individually controlled where you have 4... My guess is that somewhere you have connected power either through a switch or at the light fixture to the grounded leg (white ) of the circuit from the panel.
The fact that the breaker immediately trips off tells me you have a short to ground or to the grounded leg.

Edit: Added a drawing for switch loops from the fixtures themselves.

[Chris Barnett]

Akums Razor.... the simplest solution. Checked via a meter and small light with dental mirror but could not see the cut in the insulation from the mounting screw through the box. Had one fixture still to go when it became apparent by adding the closest then the next fixture etc. when breaker tripped. Had previously replaced the breaker and meter checked all wiring for grounds before posting this item. Was sure it had something to do with a new type transformer, and not the circuit installation.
Really appreciate the help and realizing that others, even with care, unknowingly cut insulation.
Now to put it all back together and on with business.

[Roger Frazee]

Yep that is a common mishap glad you found the problem.

[Dave Gaul]

[QUOTE=Chris Barnett;1462294]
Really appreciate the help and realizing that others, even with care, unknowingly cut insulation.
QUOTE]

When I did it as mentioned earlier, I kinda left out the "with care" part!! I fastened the clamps on the metal box with an impact driver!! Thought I finessed it enough to not cause damage, but was obviously wrong there....lesson learned!!!

Glad you found the problem, happy ww'ing to come now!