Fluorescent tube (LED) glowing constantly.

[phetphet]

Replaced a 4' fluorescent tube fitting in my bathroom. The end brackets had cracked, and would no longer hold the tube in place.

Was sold a Philips one with LED tube. PhiliSave EcoFit Set.

 

After fitting, works OK, but the tube glows constantly, even when switched off.

 

I did noticed that it does not seem to be earthed. There were only two wires.

 

Any ideas what could be wrong? Or what I can do to correct it please? 

 

TIA

[Crossy]

I'll lay odds the switch is in the neutral, can be real fun to sort depending how everything is wired.

 

Do you have any test gear, neon screwdriver, multimeter?

 

[lopburi3]

Aa above - switch on neutral rather than hot wire is common issue here.  Hopefully both wires are at the switch - which makes it easy to correct.  Just switch the wires going in/out of the switch.  Below you would change to white wires to switch from black.  The test is use neon screwdriver to check which wire lights it up - only one side of switch should light neon when turned off.  You need to use other wire if that is not the case (or rewire if not another wire in box.  Disregard the yellow wire below as you do not have.

[phetphet]

18 minutes ago, Crossy said:

I'll lay odds the switch is in the neutral, can be real fun to sort depending how everything is wired.

 

Do you have any test gear, neon screwdriver, multimeter?

 

I have a neon screwdriver and a voltage alert pen.

[bankruatsteve]

If above doesn't do it, make sure the switch is actually switching.  I have had to clean out switches filled with ant dust.  Usually, those won't switch on until fixed but suppose getting stuck "on" would be a possibility.

[Crossy]

9 minutes ago, phetphet said:

I have a neon screwdriver and a voltage alert pen.

 

With your neon check that the switch has live both sides when it's turned on.

 

If it only shows a live when off (it will only show on one side) it's switching the neutral.

 

How to actually fix it depends how much access you have to the wiring.

 

 

[bankruatsteve]

19 minutes ago, Crossy said:

If it only shows a live when off (it will only show on one side) it's switching the neutral.

 

Hmm.

 

Edit:  Not sure where Crossy was going there.  But, if you disconnect the leads at the light and then find neither side of the switch shows live, that would indicate a neutral being switched to me.

[Crossy]

16 minutes ago, bankruatsteve said:

But, if you disconnect the leads at the light and then find neither side of the switch shows live, that would indicate a neutral being switched to me.

 

Indeed, but testing without disconnecting is easier (particularly as a switched neutral will leave live wire at the light).

 

The switch being live both sides when ON is the acid test.

[bankruatsteve]

1 minute ago, Crossy said:

 

Indeed, but testing without disconnecting is easier (particularly as a switched neutral will leave live wire at the light).

 

The switch being live both sides when ON is the acid test.

So, you are testing at the light - not at the switch, yah?

[Crossy]

2 minutes ago, bankruatsteve said:

So, you are testing at the light - not at the switch, yah?

 

Testing at the switch. No need to climb ladders.

 

[bankruatsteve]

41 minutes ago, Crossy said:

 

With your neon check that the switch has live both sides when it's turned on.

 

If it only shows a live when off (it will only show on one side) it's switching the neutral.

 

How to actually fix it depends how much access you have to the wiring.

 

 

I'm pretty sure switching the Live will also show one side only live when the switch is off.  Or, what am I missing?

[Crossy]

5 hours ago, bankruatsteve said:

I'm pretty sure switching the Live will also show one side only live when the switch is off.  Or, what am I missing?

 

Not missing anything, I didn't give the whole story (it was too early), yes, that's right.

 

Acid test - Switch ON (so the light is lit):-

• Live both sides OK
• Nothing both sides NOT OK

 

 

[phetphet]

I did as you suggested. Opened switch. It is a double switch. One turns on ceiling lights, and the other, the right one in the attached image no.1, with two blue wires, is the one that switches the tube light above the bathroom cabinet.

 

Result.  Power on, switch on. Shows live both sides.

            Power on, switch off. shows live both sides.

 

When I use the neon pen on the two wires above the bathroom cabinet, that lead to the tube light fitting, (image 2),  the left one shows live when switch is on or off. 

 

Could it be that I have wired it wrong? Reversed the two wires? I only reconnected the two white wires, top one marked "blue" in image 3, and the bottom white in image 3.

 

EDIT.

Tried reversing the wires into the light fitting, and the tube still glows when switched off.

 

 

[Fruit Trader]

13 hours ago, phetphet said:

After fitting, works OK, but the tube glows constantly, even when switched off.

I am guessing the light glows at a reduced level when off?

Avoid using live check wands for faults like this as they can throw false indication in the mix. Your neon screwdriver is a little more positive but will require you finding a place to probe the conductors.

To check that you are switching live.

 

The black cable at your switches should be permanently live and is best tested using the neon screwdriver. This is linked to the adjacent switch via a blue loop.

 

In the second photo, the right hand orange twisted terminal should be neutral and should not illuminate the neon screwdriver.

[wayned]

15 hours ago, lopburi3 said:

Just switch the wires going in/out of the switch. 

Easily said but not normally easily done as most switch boxes do not have  both  live and neutral in them.  They normally have a runner , two wires, from the fixture to the box and you have to locate that runner connection and switch the wires there.  None of the switch boxes in my house have neutrals in them unless there is also a plug.  I know because I wired the house myself like it would be wired in the USA.

[bankruatsteve]

Seems like the problem is at the switch.  The way it is wired doesn't make sense to me.  Seems like the loop wire should be from the hole next to the red.  Does the ceiling light need to be on for the bath light to come on?  That wouldn't explain your problem though.

 

If you see live at both sides when the switch is off, that would indicate a faulty switch.

[Fruit Trader]

2 hours ago, bankruatsteve said:

Seems like the problem is at the switch.  The way it is wired doesn't make sense to me.  Seems like the loop wire should be from the hole next to the red.  Does the ceiling light need to be on for the bath light to come on?  That wouldn't explain your problem though.

 

If you see live at both sides when the switch is off, that would indicate a faulty switch.

Why does the switch not make sense in its current state. The live arrives on black and loops to adjacent switch on blue loop. The remaining red and blue cables connect to ceiling and cabinet light.

 

Some clues are in the photos where there is evidence of a white neutral lurking behind a twisted connector and blue used for the switched live.

 

The lights were working before conversion to LED tube so unless the guy has rearranged the switch cables its best make basic positive test at the switch before moving on.

[bankruatsteve]

2 minutes ago, Fruit Trader said:

Why does the switch not make sense in its current state. The live arrives on black and loops to adjacent switch on blue loop. The remaining red and blue cables connect to ceiling and cabinet light.

 

Some clues are in the photos where there is evidence of a white neutral lurking behind a twisted connector and blue used for the switched live.

 

The lights were working before conversion to LED tube so unless the guy has rearranged the switch cables its best make basic positive test at the switch before moving on.

It does not make sense because it appears that the loop wire (connecting live from switch-A to switch-B is coming from the switched side of switch-A.  Assuming red is the live source.

[Fruit Trader]

1 minute ago, bankruatsteve said:

It does not make sense because it appears that the loop wire (connecting live from switch-A to switch-B is coming from the switched side of switch-A.  Assuming red is the live source.

Why would you assume red is the live feed. Black is often used for live and in the current configuration makes sense.

 

Again, it was working before conversion to LED.

[bankruatsteve]

3 minutes ago, Fruit Trader said:

Why would you assume red is the live feed. Black is often used for live and in the current configuration makes sense.

 

Again, it was working before conversion to LED.

OK.  Whatever.

[phetphet]

6 hours ago, Fruit Trader said:

Why does the switch not make sense in its current state. The live arrives on black and loops to adjacent switch on blue loop. The remaining red and blue cables connect to ceiling and cabinet light.

 

Some clues are in the photos where there is evidence of a white neutral lurking behind a twisted connector and blue used for the switched live.

 

The lights were working before conversion to LED tube so unless the guy has rearranged the switch cables its best make basic positive test at the switch before moving on.

No. I haven't touched any cables in the switch. All I basically did was replace the whole tube fitting with a new one. Only two wires to disconnect and reconnect.

The only thing that I could have done wrong was reverse the two wires. In fact I have tried that to see if it would cure the fault, but it didn't work.

 

 

 

 

[sometimewoodworker]

46 minutes ago, phetphet said:

No. I haven't touched any cables in the switch. All I basically did was replace the whole tube fitting with a new one. Only two wires to disconnect and reconnect.

The only thing that I could have done wrong was reverse the two wires. In fact I have tried that to see if it would cure the fault, but it didn't work.

As has been mentioned it is quite likely that the original fitting was wired incorrectly.

 

The correct was is to switch the line connection. 

It is most probable that the neutral is switched instead.

 

The amount of leakage current would have had no effect on a fluorescent fitting. 

 

Many cheap LED fittings will be affected, yours is, it probably will have no effect on the life of the unit as the current flow when the neural is off is so small.

 

You have a few choices 

 

1) put up with it

2) keep buying different fittings until you find one that has a better power supply so it doesn't glow.

3) get someone to sort out the wiring so that you have switched line connections. (If that is the problem)

4) you house electrical supply may have a floating neutral. (If so then you need someone who understands what is going on and if you should have your neutral and earth linked in your consumer unit.)

[Fruit Trader]

3 hours ago, phetphet said:

No. I haven't touched any cables in the switch. All I basically did was replace the whole tube fitting with a new one. Only two wires to disconnect and reconnect.

The only thing that I could have done wrong was reverse the two wires. In fact I have tried that to see if it would cure the fault, but it didn't work.

 

 

 

 

Several posts have mentioned a switched neutral and I asked you to confirm with a test at the switches.

[Crossy]

On 4/8/2019 at 4:46 PM, phetphet said:

When I use the neon pen on the two wires above the bathroom cabinet, that lead to the tube light fitting, (image 2),  the left one shows live when switch is on or off. 

 

If these leads do indeed go directly to the fitting then you have a switched neutral, with the switch OFF there should be no live at the fitting.

 

For confirmation have a probe of the black wire at the switch with your neon, it should be live all the time if things are wired correctly.

 

If you can't re-wire the circuit to switch the correct side you could try adding a small 250V AC capacitor - 1uF or so (a small motor capacitor would do the trick) across the mains connections inside the fitting. Not a guaranteed fix, but worth the few Baht the cap would cost.

 

EDIT Do confirm you are getting a good solid glow from your neon. They can glow somewhat on dead (unconnected) wires due to capacitive pickup from other wires (the same effect that's causing your LED to glow).