LED strip flashing - diagnosis, replacement part, fitting

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timmmay

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#289503 9-Sep-2021 14:41

An LED strip under the vanity in our bathroom has started flashing. It's about 8-9 years old, has worked fine until now. It flashes bright for a fraction of a second, goes dark for 2 seconds, then flashes again.

My best guess is the LED driver has failed rather than the LED strip, does that sound right? The driver is the Keytech KAV-12012-I which is 230V in and 12V / 1A / 12W out. The LED strip is low power, deliberately dim, and about 2m long so power needs very modest.

Can anyone suggest a suitable driver - maybe this one? It's in the ceiling cavity so it has to cope with high temperatures easily into the 50s. Can I replace it myself or do I need an electrician to do it? I'm fairly competent at electrical stuff, but I'm not an electrician.

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#2775443 9-Sep-2021 15:11

No problem DIY replacement if it's plugged in, if you're competent then it would be legal to replace it yourself if hard-wired.

I'd connect the light strip up to any 12V DC source >1a if you've got one handy - just to check that it isn't the strip light at fault. As the original driver was constant voltage (not constant current) then the replacement you selected should be fine.

timmmay

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#2775522 9-Sep-2021 15:42

Thanks Fred. Connecting to a 12V source would be a bit tricky given locations, not impossible for two people. If the LED strip is faulty I guess I'll just replace that next anyway, and the age of the driver it's due for replacement either way.

Any comment on brand / model of driver? The old one had the mains going in one end, that goes into a junction box I think. The other end had the 12V coming out. The new one I linked to has just terminals. I'm competent to cut the cables and connect to the new driver (after testing power is off with multimeter), but like for like tends to be easier.

DonH

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#2775572 9-Sep-2021 16:42

Based on the symptoms, you can be almost certain it's the driver. Faulty LEDs can cause flickering, but only some of the LEDs would flicker. The LEDs in a long 12 volt string are wired in groups of 3 or 4, so a faulty LED will only affect a short section.

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snnet

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#2775573 9-Sep-2021 16:48

I'd agree it's most likely the driver - I usually replace drivers with ones from Halcyon or Switch for peace of mind, your one in question may work I just don't know for how long. I often chuckle at the names of failed ones I pull out like "Mean Well" as if they meant well but it didn't work out

timmmay

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#2775574 9-Sep-2021 16:50

snnet:
I'd agree it's most likely the driver - I usually replace drivers with ones from Halcyon or Switch for peace of mind, your one in question may work I just don't know for how long. I often chuckle at the names of failed ones I pull out like "Mean Well" as if they meant well but it didn't work out

If you could link to a good brand or store that would be appreciated 🙂 I'm buying retail.

Fred99

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#2775583 9-Sep-2021 17:08

I have no comment on quality of the driver you linked to, higher capacity (20 vs 12W) might mean it'll last longer all other things being equal (which maybe they aren't and maybe it won't).

Note it says to install above insulation.

LEDs (with separate drivers) seem to be shifting away from 12v. Much of it now seems to be 24v constant voltage (strips etc) - or 28-36v constant current (downlights etc).

I've been in spec houses that are only 5 years old, and half the LED downlights the builder wanted installed have already failed, presumably the drivers. Much like the early B22 and ES27 LED globes I bought years ago, they seemed to start failing as soon as I'd chucked out or lost the receipts.

snnet

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#2775612 9-Sep-2021 18:51

timmmay:
snnet:

I'd agree it's most likely the driver - I usually replace drivers with ones from Halcyon or Switch for peace of mind, your one in question may work I just don't know for how long. I often chuckle at the names of failed ones I pull out like "Mean Well" as if they meant well but it didn't work out

If you could link to a good brand or store that would be appreciated 🙂 I'm buying retail.

The one you posted above will suit

https://www.thelightingshop.co.nz/collections/driver/products/12v-20w-constant-voltage-driver

Though it is mains wired not plug in type, should be installed by a licensed electrician, or inspected by a licensed electrical inspector

However I'm not the police so...

This is assuming the total load isn't more than 20W (you actually want it to be no more than about 18, but at least 4W, non-dimming)

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Fred99

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#2775631 9-Sep-2021 18:56

snnet:

Though it is mains wired not plug in type, should be installed by a licensed electrician

However I'm not the police so...

It's considered the same as replacing a light fitting, so as long as it's done to code by a competent person in their own home, then it's legal to DIY.

(But usual proviso - if you have to ask how to do it in a forum, then nope, you shouldn't be doing it).

snnet

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#2775645 9-Sep-2021 19:26

Fred99:

snnet:

Though it is mains wired not plug in type, should be installed by a licensed electrician

However I'm not the police so...

It's considered the same as replacing a light fitting, so as long as it's done to code by a competent person in their own home, then it's legal to DIY.

(But usual proviso - if you have to ask how to do it in a forum, then nope, you shouldn't be doing it).

I'm not sure that's true - all the legislation, acts and regulations, wiring rules I studied to become an electrician are quite specific with these things in NZ - fixed wiring is legally required to be inspected or done by a registered electrician

[edit]

In addition to the clauses allowing homewoners to do things as long as they are inspected it's also stipulated they can only do so at their primary residence - not holiday homes, not homes rented or any other homes/buildings/dwellings

[edit]

Quite right, Sorry Fred99, you were indeed correct. I don't recall it being allowed in the Electricity Act without inspection, but other documents say otherwise ECP51 in particular

I don't know what laws and acts overlap and what supersedes what however, because I know a person cannot do it for reward of any kind yet my father's building license renewal test stated he could do so on client's homes

timmmay

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#2775648 9-Sep-2021 19:40

I guess I'll have to get up again tomorrow and look at the termination, whether there's plugs on each end of the current one or if it's just hard wired in. I took photos but only of the driver not the wider area.

I wouldn't have any issue cutting the current mains wiring, screwing it into the terminals of the new driver, and ditto for the DC. I would be pretty damn careful, probably turning off all power to the entire house, not just that circuit, and check with the multimeter. I'd still wonder if anything in the house is holding charge in a way that could hurt me though.

To be safe maybe I just buy the driver and have an electrician fit it. $100 or so isn't a big deal.

snnet

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#2775650 9-Sep-2021 19:48

timmmay:

I guess I'll have to get up again tomorrow and look at the termination, whether there's plugs on each end of the current one or if it's just hard wired in. I took photos but only of the driver not the wider area.

I wouldn't have any issue cutting the current mains wiring, screwing it into the terminals of the new driver, and ditto for the DC. I would be pretty damn careful, probably turning off all power to the entire house, not just that circuit, and check with the multimeter. I'd still wonder if anything in the house is holding charge in a way that could hurt me though.

To be safe maybe I just buy the driver and have an electrician fit it. $100 or so isn't a big deal.

Looks like I was in fact wrong after all, ECP51 details that you can do it yourself as a homeowner in your own home

timmmay

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#2775651 9-Sep-2021 19:52

Even if I can, and can do low voltage stuff, I suspect I should probably be cautious with mains voltage. My retire neighbor used to be an electrician until a year ago, think he's still licensed, he could supervise but probably a bit tricky for him to get into the tight spaces.

@snnet if I switch off the mains power then cut and grab the exposed mains wires (which I would avoid doing - one wire at a time) is there any risk from devices holding charge in the house?

snnet

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#2775653 9-Sep-2021 19:56

timmmay:

Even if I can, and can do low voltage stuff, I suspect I should probably be cautious with mains voltage. My retire neighbor used to be an electrician until a year ago, think he's still licensed, he could supervise but probably a bit tricky for him to get into the tight spaces.

@snnet if I switch off the mains power then cut and grab the exposed mains wires (which I would avoid doing - one wire at a time) is there any risk from devices holding charge in the house?

If you've turned the mains off, and checked that light also no longer flickers and no other lights are working you won't have an issue - just make sure the main switch IS the main switch, I see so many switchboards where things have been moved and nobody updated it! If you want to be put at ease take a photo of the inside of the board (isolation / disconnect switches are usually easy to tell apart from circuit breakers) and I'll let you know if it looks right :P Or, ask your neighbour

If you have a multimeter, use that on AC volts on the driver's main terminals too

timmmay

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#2775656 9-Sep-2021 20:03

I have a 3 month old switchboard so I know where the switch is, and a multimeter. Sounds like the risks are fairly low. I did university level electronics but that's quite different from what electricians do!

snnet

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#2775668 9-Sep-2021 20:21

timmmay:

I have a 3 month old switchboard so I know where the switch is, and a multimeter. Sounds like the risks are fairly low. I did university level electronics but that's quite different from what electricians do!

Should be all set then :)

I'm still annoyed I had several documents I'm sure told me the opposite to what is in ECP51 (because of the information I've "known" being wrong!)

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