Recessed lights Dim then Bright

[andyselectric]

I recently updated a bathroom and replaced old wiring. The branch circuit now has three recessed lights (65W bulbs). The customer recently called me that the lights in the bathroom got dim then bright, and went out.
After investigating I found all three new 65W bulbs had failed. After replacing the bulbs everything seems to be working fine. I checked the neutral connection and the voltage (varing a bit around 121V), but couldn't find anything. Any suggestions? Or was this perhaps a voltage surge?

 

[mcclary's electrical]

I recently updated a bathroom and replaced old wiring. The branch circuit now has three recessed lights (65W bulbs). The customer recently called me that the lights in the bathroom got dim then bright, and went out.
After investigating I found all three new 65W bulbs had failed. After replacing the bulbs everything seems to be working fine. I checked the neutral connection and the voltage (varing a bit around 121V), but couldn't find anything. Any suggestions? Or was this perhaps a voltage surge?

Welcome to the forum, How long had they been in service? If they were on their last leg, when one "blows",,,it creates a huge surge on the lights close to it. (the same as a set of contacts opening under load,they spark) If they were pretty much worn, it's not uncommon to blow a few at a time, but if they were new, I'd be checking all grounded conductor connections from the branch circuit all the way to the meter

 

[Dennis Alwon]

A few years back I got a bunch-- and I mean a bunch --- of bulbs by an American company- won't mention the name-- that were defective. IThey would work for maybe an hour or more and then burned out. I brought cases of them back and the company has fixed the problem. It was bad-- every electrician in town went nuts and one of them had just trimmed a huge house with about 150 bulbs. After the first batch went he replaced them all.

 

[andyselectric]

The branch circuit from the breaker (new also) to the lights was just installed a couple of weeks ago along with new recessed lights. Nothing else on this branch circuit.

 

[LarryFine]

Andy, welcome to the forum!

Nothing else on this branch circuit.

Now that's what I call dedicated.

 

[mxslick]

Andy, welcome to the Forum ...

If it was ONLY the lights that did the dim, bright sequence then it is possibly bad bulbs. One shorting out as it failed would affect the others.

If the symptoms happened elsewhere in the house as well, there are two possibilities:

Bad/loose main neutral connection in the panel, meter socket or service drop (Latter two are POCO's responsibility) or

There was a one-time event on the poco's lines that created a surge strong enough to blow the bulbs.

In either case ask your customer to check out all of their electronic equipment and any surge strips for damage.

 

[andyselectric]

Thanks, I appreciate the insight!

 

[LarryFine]

Andy, on a serious note (hey, it could happen! :grin, if all three light do the same thing at the same time, it has to be at, or before, the first light from the switch. In other words, it must be something they all share.

I'd start with seeing if a voltmeter at the switch varies with the brightness. If it does, its ahead of the switch. Check for the same varying voltage at the panel, and any splices between. It's gotta be somewhere.

 

[sameguy]

Almost like the thermals are bad.

 

[nate roach]

Yep I agree with sameguy,, thermo couplers

 

[LarryFine]

Not if they flicker in unison.

 

[mcclary's electrical]

Not if they flicker in unison.

I agree with Larry, first off, a thermistor does not flicker,,,it just OPENS ad stays open until it cools,secondly, there is no way one thermistor will make the others flicker with it, and third, there is no way ALL 3 thermistors flickered at the sme time.Larry's and MX sclick's post was really all the direction he needs to fix this problem

 

[andyselectric]

Recessed lights Dim then Bright

I checked out all the grounded connections, didn't find anything. Could be some bad bulbs, as mentioned earlier, or a voltage surge (perhaps).
I asked the customer if they had problems in the past, and of course the answer was no. I'm currently waiting for the symptom to happen again, as its been a couple of weeks with no problem. My next step would be to have the POCO out, pull the meter and check the grounded connections from the service back.