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light bar

 
 
Reply Fri 7 Dec, 2007 09:23 pm
So anyway in our master bath over the vanity we have a light bar which is essentially a wooden box about 5 ft wide holding 6 bulbs. Last week the 3 bulbs on the right side went out so I bought new bulbs (odd I thought, that 3 bulbs would burn out at teh same time) anyway I replaced the bulbs and got darkness so I tried the old bulbs in the sockets on the left and they lit up my life. So, how can a single light fixture albeit 6 bulbs only light 3 bulbs?
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Type: Discussion • Score: 1 • Views: 3,007 • Replies: 37
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dadpad
 
  1  
Reply Fri 7 Dec, 2007 09:28 pm
The wiring is most likely in series. This means that power is applies to light 1 the first on the right. the power then travells to light 2 then to light 3.

It appears from your description that there is a fault in the wiring between lights 3 and 4.

check if light 4 is "good" by removing all globes except for light 4
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dyslexia
 
  1  
Reply Fri 7 Dec, 2007 09:34 pm
lights 1-2-3- all work;;;; lights 4-5-6 don't
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Rockhead
 
  1  
Reply Fri 7 Dec, 2007 09:41 pm
Dys, if ya wanna know if it's live, lick yer finger and.....you know.... Shocked

Diane will need to watch with a phone handy, of course....

kRAFTY IN kANSAS
0 Replies
 
dyslexia
 
  1  
Reply Fri 7 Dec, 2007 09:43 pm
Rockhead wrote:
Dys, if ya wanna know if it's live, lick yer finger and.....you know.... Shocked

Diane will need to watch with a phone handy, of course....

kRAFTY IN kANSAS
She said she would lick something else of mine if I promised to...you know, test the socket.
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dadpad
 
  1  
Reply Fri 7 Dec, 2007 09:51 pm
dyslexia wrote:
lights 1-2-3- all work;;;; lights 4-5-6 don't


Wiring fault between globes 3 and 4. you will need to take the cover off "the box"

First dissconnect from power source

If the unit is hard wired Ie not plugged in to a power point you will need to turn the household power supply off completely. for the whole house.

Take the cover off the box and visually check the wiring between globes 3 and 4. The fault will most likely be where the wiring leave globe 3 or joins globe 4.
0 Replies
 
Chumly
 
  1  
Reply Fri 7 Dec, 2007 10:05 pm
dadpad wrote:
The wiring is most likely in series. This means that power is applies to light 1 the first on the right. the power then travells to light 2 then to light 3.

It appears from your description that there is a fault in the wiring between lights 3 and 4.

check if light 4 is "good" by removing all globes except for light 4

No No No! 120 VAC residential lighting loads are not in series!

Certain types of Christmas lights are in series and some specialty trim lighting may also, but 120 VAC residential lighting loads are in parallel.

However the connections behind the facia can have been done in such a fashion as to have a given number of the sockets become un-powered whilst the rest of the sockets remain powered.

On the other hand I would start with the most obvious regardless of any coincidences dyslexia may have encountered.

From dyslexia's "decryption" I would start with an inspection of the suspect sockets, and then the connections behind the facia as discussed above.

Actually if it was me, I would go buy a brand-new fixture as it sounds like this wooden box contraption belongs in the Dark Ages if not in a darkened bathroom.

How do I know all this crap you ask? I am a Journeyman Electrician (check my sparks).
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Chumly
 
  1  
Reply Fri 7 Dec, 2007 10:30 pm
dadpad wrote:
If the unit is hard wired Ie not plugged in to a power point you will need to turn the household power supply off completely. for the whole house.
No No No! Under no normal circumcises would you ever need to turn off the power to the house. This branch circuit will be fed from a breaker in the panel, that's the only circuit you need to shut off.
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Rockhead
 
  1  
Reply Fri 7 Dec, 2007 10:33 pm
Chumly, as cryptic as that was, I think that was your best argument on the forum so far.... Shocked

RH
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dadpad
 
  1  
Reply Fri 7 Dec, 2007 10:35 pm
Chumly wrote:
dadpad wrote:
If the unit is hard wired Ie not plugged in to a power point you will need to turn the household power supply off completely. for the whole house.
No No No! Under no normal circumcises would you ever need to turn off the power to the house. This branch circuit will be fed from a breaker in the panel, that's the only circuit you need to shut off.


And you better hope he shuts off the right one.
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Chumly
 
  1  
Reply Fri 7 Dec, 2007 11:00 pm
Rockhead wrote:
Chumly, as cryptic as that was, I think that was your best argument on the forum so far.... Shocked

RH
Now that is funny!
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Chumly
 
  1  
Reply Fri 7 Dec, 2007 11:14 pm
dadpad wrote:
And you better hope he shuts off the right one.
Yes the correct branch circuit breaker can be readily identified by two somewhat redundant methods and one pretty much fail-safe method

1) the light in question will extinguish

2) A conventional VOM (volt / ohm meter) on the load side of the wiring in question will confirm

3) There is a device colloquially called a ticker that is quite cheap and reasonably reliable. With this device you need not disconnect any wiring but simply place the ticker near the wires / light bulbs / sockets etc in question and the magic of capacitance does the rest.

It should be understood that there may be other circuits in the junction box in question, assuming there is a junction box in question, and that these should be metered as well (if a novice is fooling around) even though any other (still hot) circuits will have no effect on the circuit in question given that all is wired correctly.
0 Replies
 
Intrepid
 
  1  
Reply Fri 7 Dec, 2007 11:35 pm
Rockhead wrote:
Chumly, as cryptic as that was, I think that was your best argument on the forum so far.... Shocked

RH


I have to agree. Chumly actually made total and complete sense with no sense of fallacy involved.

Of course, if Dys is not sure about the power actually be off to the circuit. It WOULD be best to power down everything in the name of safety. Wouldn't want Lady Di to have to drive the Porche to the funeral.
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dadpad
 
  1  
Reply Fri 7 Dec, 2007 11:50 pm
Everything chumly has said is 100% correct given that everything is as it should be.

Having no knowledge of dys's electrical system or if he's actually got ciruit breakers (we don't, just ceramic fuses) I was being ultra safe when i suggested turning of the power to the whole house

Quote:
Certain types of Christmas lights are in series and some specialty trim lighting may also, but 120 VAC residential lighting loads are in parallel


Valid only if the unit conforms to standards. If its a home made job who knows.

I will however defer to the sparky. Always better to consult an experienced professional.
0 Replies
 
Chumly
 
  1  
Reply Sat 8 Dec, 2007 12:11 am
If the lights in question were in series (lets assume 3 X 2) in what might be kindly called series-parallel network (but in actuality some sort of screw-up as you suggest) then each bulb would receive only 40 VAC and thus each bulb would be very dim at best.

The above should explain why the bulbs cannot have been in series even as a screw-up.
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Chumly
 
  1  
Reply Sat 8 Dec, 2007 12:31 am
I gotta admit it's kind'a fun that my postings which appear to have elicited the most appreciation(?) from both Rockhead and Intrepid would also appear to be the postings they understand the least.
0 Replies
 
dadpad
 
  1  
Reply Sat 8 Dec, 2007 12:38 am
Chumly wrote:
I gotta admit it's kind'a fun that my postings which appear to have elicited the most appreciation(?) from both Rockhead and Intrepid would also appear to be the postings they understand the least.


I dont "get it" at all. <shrug>. I've gotten used to the fact that cryptic stuff goes over my head.
0 Replies
 
dagmaraka
 
  1  
Reply Sat 8 Dec, 2007 12:46 am
it's a trial and error, dys. just rip the darn thing off the wall and jiggle some wires. it usually works for me.
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edgarblythe
 
  1  
Reply Sat 8 Dec, 2007 12:48 am
If half of the lights are burning, when you trip the correct breaker, they will go out, and you then can safely handle it.
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Chumly
 
  1  
Reply Sat 8 Dec, 2007 01:05 am
When you "trip a breaker" it means that there was an overcuuent fault condition, thus the phrase you are looking for is "switch off the breaker".

Also as discussed above all is not necessarily safe if the branch circuit driving the lights is switched off from the breaker because there may be other circuits that are still hot in the junction box - assuming one needs to access said junction box.

Yes it is even possible and legal if done correctly to have more than one circuit in the lamp fixture itself thus even if junction box access is not needed all risk is not removed until the circuit count is established.
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