I got today very weird lights problems that I cannot understand. I have
6 recessed lights on one circuit in basement: three in one area, three
other in another but very close to the first three. When I turned the
light switch on today one of recessed light bulb (65 W halogen) blew
off. I replaced it with another one and now I have very weird
situation. Three lights in the area that I replaced bulb in works only
in half power as if they are dimmed by 50%. If I leave only one bulb of
three it works OK, if I put the second one, does not matter which they
are both dimmed. Three other lights work OK. I checked with multimeter
and found that when two bulbs are appeared dimmed the voltage in the
third recessed light socket is 120V. Why do I have bulbs dimmed? What
could be the reason for this situation? Note, I did replace another
bulb but it didn't help. These six lights are switched by regular 3-way
switch (not dimmer) and are on 20 A circuit and share the same circuit
with 9 recessed lights in another room in basement.
Sounds like you have a 'floating' or disconnected neutral somewhere. Either
a loose connection at one of your light fixtures or at the panel. Check all
the white wires.
Do you have any shared neutral 'Edison circuits? This is where 2 hot
circuits both on different 'poles' in the panel, share one neutral wire.
You can also have an unintentional 'Edison circuit' of sorts when someone
wires neutrals from different circuits together in a junction box somewhere.
In either case if a neutral is 'floating' then you will get weird things
happening like dim lights or neutral wires that arc and shock you when you
disconnect them even though the power for that circuit was off... BTDT.
Also check that none of your grounds are connected to neutrals.
I agree with Kevin. It sounds like a floating neutral. That is a
disconnected wire(s) someplace. It could be in a different room or at the
breaker box or almost anywhere in your home.
I suspect that since you did not know about that possibility, you don't
have the knowledge and or experience to hunt this down efficiently and
safely. This may be one that you should call in the pros for.
Note: this can be dangerous. I once worked for a man who had just moved
due to a fire cased by this kind of problem at his old location. He had
ignored the problem too long. Don't let that happen to you.
Is is possible that when you changed the bulb you spun the light socket and
disconnected a daisy chained neutral?....I agree with the other posters on
the problem and hey, listen to Joe...fix it now it's a dangerous
Thank you all very much for the advise. however, i do not understand
why if neutral wire is loose voltage at recessed light socket is 120V?
Also I have some additional data. If I put only one bulb of three (does
not matter which one) it seems to be working at 100% or close to that.
If I put the second one, both immediately dimmed, if I put the third
one al lthree dimmed even more.
One thought are you measuring from hot to neutral or ground?
It could also be a similar problem like a bad hot or neutral connection
somewhere in the line. If it were resistive it would act like your
symptom. When you measure with a meter it would depend on where the
power enters the 3 (probably) daisy chained lights. If you were at the
entry point you would measure full voltage. If you were at the end of
the chain you would see a reduced voltage ie downstream of the dimmed
lights. Often these resistive connections are not linear. 1 bulb>near
full voltage, 2 bulbs more current draw> bad junction heats up>more
resistance>more voltage drop. Like they say get it fixed. When your
lights are dimming like that there is a voltage drop across the bad
junction and heat is being generated there equal to the voltage drop
times the current draw. Fire hazard.
when the lights are dimmed and you don't have a dimmer, something is
probably getting hot and could start a fire.
when the bulb burned out the surge of current could have damaged a
switch or a connection which is now getting hot when the load of
several bulbs pass through it...
if a switch or anything is getting hot turn it off immediatly and keep
it off until it is fixed
Guys, I really need help. I opened up three recessed lights fixtures
and here is what I found that confuses me even more. Lights 1, 2 and 3
work OK and do not dim. Lights 4, 5 and 6 dim if more then one light
from this group is on. If all are on all three dim even more. Power is
on fixture and comes to the fixture #3, then to fixture 4. From 4 it
goes both to 5 and 6. I opened both #3 and #4. I measured voltage
between neutral and hot wires and between hot and ground wires when two
lights from the problem group are dimmed. Voltage at fixture #3 is OK,
120V between hot and ground or neutral. However, at fixture #4 voltage
is 60 V between hot and neutral, 60 V between neutral and ground and
120 V between hot and ground. What can be wrong with the wire
connecting #3 and #4? The wire is BX armored cable AWG12. And what's
the best and safest way to fix the problem? I would like not to remover
that wire since to do so I have to rip sheetrock in half basement.
However I can put another cable in parallel.
Sorry just can't figure out what your problem is with the information given.
Seems to me that in order to have the symptoms you describe there may be
multiple wiring problems with that circuit.
From my experience using a volt meter to diagnose these kinds of problems
leads to more confusion than help especially when open neutrals are
I have better luck using a simple light tester to find the hots and then
using a continuity tester with power off and all light bulbs removed.
It may help to diagram that entire circuit and account for EVERY wire in all
the boxes. Then label and disconnect all the wires and systematically go
through each wire and fixture and check for opens shorts etc with a
continuity tester. (There is probably one built into your volt meter).
Some other things to check out:
Are there any doorbell or other transformers attached to any of the boxes?
Do any of the light or switch boxes contain wires from other circuits?
Are there any other circuits in the house acting funny?
Thank you all guys. There was indeed loose neutral wire, however not
where I expected. I had to rip and patch quite a few places in basement
sheetrock ceiling. This time I created a sketch of all wiring in
It violates code to have any boxes that cannot be accessed. Your
map should not come into play if you can open every box. There
should be no joints that are not in boxes.
(top posted for your convenience)
Keep the whole world singing . . . .
DanG (remove the sevens)
What are you talking about? All connections are made inside recessed
light boxes that obviously cannot be opened without ripping ceiling. I
just don't understand how else you can wire multiple recessed lights? I
have more then 50 of them throughout the house, all work was inspected,
never had any questions from inspector. Also never had before any
issues with recessed lights or any wiring, this is first time in my
life I have problem.
With a recessed light, you know where the connections are. Just putting a
connection or splice in a box hidden in the wall or ceiling is not good as
it may never be found, can cause problems after a time. That is why we have
IIRC someone already told you how to access the "recessed" boxes on the
fixtures. If you look close, inside the can you will see some screws,
remove them and the can comes out, making the make up box accessible.
There is not a fixture made where you cannot access the wiring directly.
Sometimes you have to disassemble part of the fixture and/or remove a metal
cover plate, but never would you have to tear out wall/ceiling just to get
to the connections.
It is extremely rare that a problem develops in wires between fixtures or
switches unless someone has driven a nail or something. Even that is rare
unless wire was not installed correctly to code.
There's got to be 50 ways at least. Depending on the layout of your house.
Could be a star pattern branching out from one fixture in the middle. 'T'
patterns, 'L' anything. Most likely it is done in a way that uses the least
amount of wire. You may even have more than one circuit inside a single box
especially at a multiple switch box.
Not really relevant. Fixtures /sockets switches can break. Connections can
jar loose by foot traffic on the floor above etc. An inspecter does not
touch every connection or follow every circuit etc. Maybe 1 or 2 in the
entire house. I have seen inspectetors come and look at a house, in and out
in 15 minutes and that included about 10 min. of BS.
Inspections/ permits are only a revenue generator for your city. There is no
guarantee made that everyting is correct or up to code or that your house
doesn't burn down due to electrical problems etc.
With most of these "can lights" you can access the junction box by
dropping the can fixtures. It is not intuitive how this is done if
you've never seen one before. As I remember this was a Halo 6" so if
you downloaded the PDF for this model you could see how this is done.
Usually there's 3 black clips that are in the perimeter of the can and
sit in long slotted holes. You slide the bottom tab upwards to where
the slot widens and the black clip will pop inside the can. Then you
can pull the entire can out of the plate that holds it to the joist
spanner and it will hang on it's pigtail that comes from the junction
box. It's also a real pain working on that box through this little
hole. I use mirrors and often swear a lot as the original installer
often leaves these little short pigtails.
Yes it is also true that it violates code to hide wiring junctions. I
can't tell you how many times I've had to bust out drywall to find a
junction that someone had buried. Quote "You stupid @*&#(@)" or
something to that effect.
The thing I've found a lot is an upgraded panel with conduit running
everywhere that's visable in the basement then when you go on the upper
floors and start opening up fixtures you find knob and tube everywhere
and can't find where these "f***ers" junctioned to make this
transitions! And don't get me started on pulling out knob and tube,
talk about buried junctions. I have one client with an upgraded 250A
service panel where you knock off one breaker and everything on the 2nd
floor (6 rooms and hallway) goes dead!
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