Delay in secondary light illuminating

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I have two exterior lights that are operated from a single switch within the house. I wired these in a few years ago. Here's an image of the light:
upload_2020-1-6_12-7-16.png


The live feed goes to light #1 along with the switch wire and this the has a cable that activates a second light too. The second light (identical) is approximately 10 metres away.

I am unsure of this has always been the case but I noticed that when I switch the light on, light #1 immediately illuminates but the second light probably takes 2-4 seconds before it lights up.

I thought it may be the bulbs and changed both from the existing fluorescent to LED's:
upload_2020-1-6_12-10-53.png


I still get the same behaviour. I checked connections in both sets of terminals and all seems fine.

I have a similar arrangement elsewhere in the house (a slave light or whatever the technical term is!) and haven't noticed a similar delay. Curious to understand why this is the case.
 

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Electronic ballast starting to fail? Or is fitting number 2 a switched-start unit?
 
The second light took almost 30 seconds to come online yesterday.
I am unsure on what you mean by a switched start. Its a relatively cheap external bulkhead and both are operated from a single switch.

Does the above indicate that the unit needs to be replaced?
 
There are two methods to start and run a fluorescent lamp, one is a simple coil of wire which has two jobs, one it gives a voltage spike to assist starting and two it limits the current through the lamp, the other is to use an electronic starter this is far more complex, however it turns the 50 Hz into kHz so reduces the strobe effect and it also limits the current more precisely so it increases the tube life and the light output from the tube meaning a fluorescent tube is nearly as good as a LED but far cheaper.

So when we fit a LED in a fluorescent lamp with a wire wound ballast the ballast becomes a resistor, which reduces the voltage to the LED which the LED's driver compensates for, however in real terms once one includes the losses from the ballast it does not make the LED any more energy saving than the fluorescent it replaced, other than being a lower output, so common for a LED to be 2200 lumen when replacing a fluorescent which was 5600 lumen so the wattage reduction is simply because it gives out less light.

However in the main one can't fit an LED in a fluorescent fitting with a HF electronic ballast, with the 2D unlike unfolded tubes the ballast is part of the unit that the tube plugs into, and can't easy be bypassed, so it seems the built in driver in the folded tube is designed to make the electronic ballast think it still has a fluorescent plugged in, so I would guess it is some thing to do with this which causes the delay in starting.

I did test a straight replacement tube, and although the tube states 22 watt, which is what it takes, the fitting as a whole was drawing more like 28 watt, so as a whole less efficient than a fluorescent tube, however in the kitchen where fitted we did not need 5400 lumen, what we needed was the light to be spread over 5 foot, so reducing output to 22 watt and 2200 lumen was not a problem.

Switched mode is a method to control output, if you switch the supply on/off/on/off quickly so it is only on for half of the time then that is the same average output as putting a resistor in the output to half the voltage, but it does not cause the heat of a resistor so saves energy, this is inside the ballast and nothing to do with the switch on the wall.

You have dropped from 1050 lumen for 16W fluorescent to 750 lumen for the LED replacement so only way it saves energy is it produces less light.
 
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Is there a starter behind the lamp back plate, if unsure post a picture of the inside with the lamp removed as you can usually tell from that
 

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