The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Topic Options
Rate This Topic
#166938 - 08/01/07 08:32 PM Flickering lights
cookcc Offline
Registered: 05/26/07
Posts: 28
Loc: California ,Long Beach
I went to a couctomers house to fix some overhead floressent lights that were not working in the kitchen and the bathroom, the coustomer ( 91 year old lady ) says she leaves the switches on all the time, and since the lamps were all blown out with the exception of one fixture in the kitchen and one fixture the bathroom, (with a total of three fixtures in each room) the constent voltage being applied to the non working fixtures ballasts had caused the ballasts in those fixtures to go bad which I comfirmed two and decided to change all 4 of them (The ballests were leaking like a bad electrolitic capaciter), I also lamped the fixtures with new rapid start T8 30 watt type lamps and now she has light in both rooms but the lights flicker slighly and I'm not happy with the end result and would like some feed back as to what would cause this, also I checkesd the tomb stones and read 135-140 volts AC !!!!! I also checked the voltage going into the the ballest and read 120 Volts.
Thanks in advance.
Work Gear for Electricians and the Trades
#166946 - 08/01/07 10:33 PM Re: Flickering lights [Re: cookcc]
e57 Offline
Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
Electronic ballasts, or magnetic? Magnetic are going to flicker anyway, electronic way less.

First thoughts would be grounding - the lamps need to be near a grounded surface... Second thoughts would be "burn in time" - the lamps need to vaporize the mercury in the lamp, otherwise you get a glowing swiggle. Intiial start up should be left on over night at least. Sounds dumb but it works.
Mark Heller
"Well - I oughta....." -Jackie Gleason
#166976 - 08/02/07 06:19 PM Re: Flickering lights [Re: e57]
Scott35 Offline

Broom Pusher and
Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
What type of "Flickering" is being experienced?
  1. Is it a "Pulsating" type of flickering, with "Brown Corkscrews" flowing inside the Lamp?
  2. Is it a random, non consistent flicker, with possible audible sizzling sounds at the fixture - or "Noise" in the form of spuratic lines seen on Television, in the lower VHF channels (2 through 6)?
  3. Is it repeated flicker across one Lamp?
  4. Is it transient, short term flicker on all lamps of a given fixture?
  5. Do any other fixtures act funny - if yes, what is observed?
  6. Are Incandescent Lamps dimming and flickering while the Fluorescents are?

If #1 is observed, this may be associated with new Lamps' "Burn-In" time, and should cease after a few days.
Another reason may be very cold conditions, and moisture ("corkscrewing" is normally related to dampness and cold)

#2 scenario is when the pins of a Lamp are not seating properly in the Lampholder.
Spin the Lamps around to verify proper seating.
If the Ballast is an Electronic Instant Start type, verify that you have connected both wires at the Lampholder to the Ballast lead wire.
Electronic Instant Start Ballasts typically only have one lead wire to each Lamp at one end, and the opposite ends connect to a single red lead from the Ballast.

Scenario #3 indicates a poor connection on a Lampholder, or a Lamp which is failing prematurely.
This may also indicate a Ground Fault issue from a Lamp lead, or a bad circuit in the Ballast.

Scenario #4 would indicate a drammatic voltage drop occuring very rapidly, which may be from any external loads on the same circuit as the lighting.

Check over this list, plus the one from Mark (E57) and let us know what's up.

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
#166982 - 08/02/07 07:51 PM Re: Flickering lights [Re: Scott35]
cookcc Offline
Registered: 05/26/07
Posts: 28
Loc: California ,Long Beach
Thanks for the info I will post a follow up saterday night or sunday.
#166984 - 08/02/07 11:37 PM Re: Flickering lights [Re: cookcc]
Trumpy Offline

Registered: 07/05/02
Posts: 8560
Loc: SI,New Zealand
From my own experiences with Fluorescent fittings and I have installed hundereds of them, it sounds to me like more of the first problem, just the burn-in period, T8's take a while to get seated when first installed, with either controls on them.
However, if you do come across a flashing effect from a certain tube with magnetic ballast, I'd say replace the starter.
Failing that, replace the tube, dud tubes are not un-common.
If a tube stay's lighted at both ends after replacement, your ballast is faulty.
Let's face it, these days if you're not young, you're old - Red Green grin
#166989 - 08/03/07 06:16 AM Re: Flickering lights [Re: Trumpy]
pauluk Offline
Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I've found that the 8 ft. lamps especially (with conventional ballast) need a reasonable burn-in period before (a) they stop flickering slightly and (b) start quickly at each switch on.
#167071 - 08/04/07 07:10 PM Re: Flickering lights [Re: pauluk]
cookcc Offline
Registered: 05/26/07
Posts: 28
Loc: California ,Long Beach
After the insight I receaved here I had my coustomer burn the lights all knight and made a special visit today to find her excited that the flickering had stopped however I can still see it slightly but I am confident that as the remaining mercury burnes up the light will burn steady.
Thanks alot guys!


2017 NEC and Related
2017 NEC
Now Available!

Shout Box

Recent Posts
Looking for older post
by sparkyinak
Today at 12:27 AM
License exam
Yesterday at 11:33 PM
Members: Non-Members: Did you know?
by Admin
Yesterday at 02:34 PM
Safety at heights?
by HotLine1
01/21/17 08:51 PM
International Wire Colour Codes
by Texas_Ranger
01/21/17 03:29 PM

Who's Online
1 registered (sparkyinak), 108 Guests and 11 Spiders online.
Key: Admin, Global Mod, Mod
New in the Gallery:
Desk-mounted "power-board"
Top Posters
gfretwell 9066
Trumpy 8560
pauluk 7693
HotLine1 6833
sparky 5545
Member Spotlight
Member Since: 08/01/07
Posts: 62

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals