2

I have a 15A circuit in my house which has only two things that draw meaningful current: my TV and a set of 8 LED floodlights around my house's exterior. The TV draws max 150W and the bulbs (Sylvania Night Chasers) draw 22W each for a total of ~176W.

I frequently (maybe 90% of the time) trip the circuit breaker if I start with the TV on and then turn on the floodlights. If I turn on the floods with the TV off, no problem. If I turn on the floods and THEN turn on the TV, no problem.

My intuition was that inrush current might be the cause and, to my surprise after searching, it turns out LED lights are known to have large inrush current because of the capacitors in their driver circuitry. My theory is that, in my case, since each of the 8 bulbs has its own circuitry, this is leading to a very large inrush current and the breaker is not happy with that.

I really like the bulbs so I'd like to solve this without installing new units where lots of LEDs share common driver circuits. What are some possible ways to fix this situation? I can think of 3:

  • My electrician suggests simply pulling the circuit apart and making sure the floods are on their own 15A circuit. I appreciate this but it feels like a band-aid?
  • I understand that there's such a thing as an inrush current limiter. I have no experience with them though and can't tell if it's appropriate to my situation.
  • The flood bulbs are dimmable and I can imagine a device might exist that, when I turn them on, smoothly ramps them up rather than all at once - but I don't know enough about LED drivers to know which side of the driver the dimming happens so maybe this is not relevant.

EDIT: added pic of breaker per request in comments:

enter image description here

14
  • 9
    I can't see how two devices(tv plus 8 lights) using less than three amps running can trip a 15 amp breaker on start up. Even most motors do not have that great of start up amp range.
    – crip659
    Feb 20 at 18:33
  • 1
    Circuit breakers have been known to go bad over time. Have you tried replacing it?
    – HoneyDo
    Feb 20 at 18:51
  • 3
    Most breakers should handle the short period of saying worst case of 30 amps of inrush, unless there is typo in your watts. It could be a breaker that has weaken and now trips on less amps, but would be concern there is an electrical problem. This is just a simple breaker and not one with lights/test button like a GFCI/AFCI?
    – crip659
    Feb 20 at 19:43
  • 3
    Most AFCI and GFCI breakers have some sort of indicator - different color lights or different sequences/number of blinks, etc. to indicate whether a trip was AFCI, GFCI or overcurrent. Before dealing with anything else, we need to find out what type of trip is occurring. If you can't figure that out, upload a clear picture of the breaker and we should be able to tell you how to find out - it varies by brand. Feb 20 at 20:22
  • 6
    Can you google up the instructions for that model of breaker and follow the procedure for distinguishing an arc fault vs an overload/short circuit trip? That will help enormously. Feb 20 at 22:22

4 Answers 4

4

This is pretty weird - it takes a lot of inrush to actually pop a breaker. A typical 15A thermal magnetic breaker takes 150A or more for one second to trip, and 500+A to trip in a tenth of a second. Have you confirmed that it's not a defective breaker?

There's a couple of approaches here that could help you.

  • Change out the brand of bulb. It's possible that other bulbs may not have this inrush problem. You could confirm that it's actually inrush by temporarily removing bulbs one at a time until the breaker no longer pops. Once you have confirmed that, time to try another brand of LED.

  • Replace the switch with a slider type dimmer switch. It's impossible to turn those on instantly, so just by turning on the switch you will automatically be limiting inrush. One trick to this solution: most dimmer switches are only rated for 150W of LED lights. Your 176W of lights will exceed the capacity. You will either need to split the lights between two dimmers, or locate a 200W+ LED rated dimmer switch.

6
  • 2
    Comment not answer: 21k lumens of light is a lot of outdoor lighting. The place must look pretty bright with all these lights on!
    – KMJ
    Feb 20 at 18:54
  • 7
    OP didn't mention that this is a prison and those are the security lights.... :D
    – FreeMan
    Feb 20 at 19:08
  • @Freeman - Outstanding! :-P
    – DaveBurns
    Feb 20 at 19:16
  • @KMJ - 21k of lumens is a lot but it's on all 4 sides of the house and aimed to cover an acre. That combined with a color temp of 2700k and it's not as bright as it seems on paper. But maybe my neighbors are just being polite. :-)
    – DaveBurns
    Feb 20 at 19:18
  • I agree that it seems like the breaker should handle the inrush but the order of events I describe make it hard to understand other possibilities. That said, new breakers are cheap so it's worth a try. I like the idea of pulling bulbs one by one to see if there's a threshold. Will try. I have a Lutron Diva dimmer elsewhere in my house rated for 250W of LEDs so I know they exist. Great ideas!
    – DaveBurns
    Feb 20 at 19:20
2

First thing to do is to find out what kind of a breaker trip you have and do some basic diagnostics as defined by Siemens. This document has all the details.

Once you determine if this is an overload vs. AFCI we can work on a solution.

3
  • 1
    Seems more of a comment than an answer. Yet...
    – FreeMan
    Feb 20 at 23:07
  • 3
    @FreeMan Nah, it's advice and seminal information which already may lead to a solution. Feb 21 at 12:37
  • 1
    Great info. I had no idea AFCIs offered any info on why they tripped. I'll spend time experimenting this weekend.
    – DaveBurns
    Feb 24 at 17:32
1

I have a 15A circuit in my house which has only two things that draw meaningful current... I frequently (maybe 90% of the time) trip the circuit breaker if I start with the TV on and then turn on the floodlights. If I turn on the floods with the TV off, no problem. If I turn on the floods and THEN turn on the TV, no problem.

that implies there are 1 or more other items on the circuit, which by your reckoning don't draw meaningful current? so assuming there really isn't some other significant device on the circuit your problem sounds like a combination of the inrush current of too many LED drivers in addition to power factor. the tv and LED's are all capacitive / leading power factor which do not help.

My intuition was that inrush current might be the cause and, to my surprise after searching, it turns out LED lights are known to have large inrush current

https://professional-electrician.com/technical/mythbusting-with-zano-controls/

It’s a contentious subject, but independent testing has found a huge disparity between the wattage listed on an LED’s box and the power it actually consumes.

combine numerous lights each having their own driver, all on an AFCI breaker which have gained notoriety for nuisance trips, and there you go.

simply test run 1 bulb, 2..3..4 bulbs and find what at what total number trips reliably and then doesn't, that will validate your theory on led inrush current being the problem, in addition to using a meter to measure inrush current on the circuit and also a watt meter ($10 amazon) to measure power factor. And of course you could test swap the afci breaker with a $10 traditional 15A breaker and see if it's more of an AFCI nuisance trip problem.

https://www.eaton.com/gb/en-gb/catalog/lighting-and-controls/inrush-limiter-for-led-lightings.html

LED current inrush limiting isn't new, and while I feel like your electrician should know about them I also just watched goodluckkarly on tiktok ask if anyone has ever known about how you can just pick lemons off a tree. The solution to your problem is measurable, testable, and solvable; you said this crowd is tough... I wouldn't describe the crowd here as tough.

3
  • 1
    Oh -- what's triggered is not the thermal, slow fuse but the arcing protection which by design reacts to short (in the 100kHz frequency range, which means ~10 microsecond periods) bursts of current. Makes much more sense. Yeah, we don't have that here. Makes me wonder whether a ground fault detector could also trigger -- after all, there is no corresponding back current while the capacitors charge, is there? Feb 21 at 12:30
  • Oh, a regular ampere meter may not detect the inrush current at all, you'd need an oscilloscope for that. The sustained load is an order of magnitude smaller than the actual fuse rating. Feb 21 at 12:34
  • I'll add that all of these light fixtures are two stories up so, while the idea to learn more by incrementally removing bulbs is a great one, it's not the easiest or quickest. I'm going to try some other things first.
    – DaveBurns
    Feb 21 at 15:57
0

I agree fully with crip659's assessment that this seems to be an unlikely cause of a breaker trip. Maybe there's a short somewhere that you just haven't found yet.

However, since the bulbs are dimmable, simply replace the simple toggle switch with a dimmer switch. When you want the lights on and the TV is already on, turn the dimmer all the way down, turn the lights on, then bring up the brightness to your desired level.

An LED dimmer isn't particularly expensive, so even if this doesn't work, you haven't lost a lot in giving it a try.

2
  • I can't figure out where a short could be if things DO work depending on the order I turn things on. Ideas?
    – DaveBurns
    Feb 20 at 19:22
  • 2
    If there's a loose connection, it might be getting heated by having the TV on. Once the lights are turned on, that loose connection causes the short. Beyond, that, no guesses.
    – FreeMan
    Feb 20 at 19:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.