Polarity on this led driver

HappyHippyDad · Aug 4, 2023

Hello all.
Just a bit unsure about polarity on the primary side of this LED driver. 99% certain one relates to live and two to neutral?

DPG · Aug 4, 2023

The AC input can probably be connected either way round on that.

HappyHippyDad · Aug 4, 2023

DPG said:
The AC input can probably be connected either way round on that.

'Probably'?

DPG · Aug 4, 2023

HappyHippyDad said:
'Probably'?

I know, sorry - it's difficult to be 100% sure. Have you checked the instructions, he said optimistically

HappyHippyDad · Aug 4, 2023

DPG said:
The AC input can probably be connected either way round on that.

Just got through to them. No polarity. You were correct

DPG · Aug 4, 2023

HappyHippyDad said:
Just got through to them. No polarity. You were correct

Nice one. Wish I'd been more confident now

steveyboy10 · Aug 4, 2023

Yep. If it doesn't say L - N then there is no polarity. Clever little things lol

oscar21 · Aug 4, 2023

Even if it does say L&N it still makes no difference, there is no way for any electrical product to know which way round the AC is connected if its just a two wire connector.

The only thing I've ever seen which makes a difference is a boiler and that's because the flame sensor measures it reading to earth. So if L&N are reversed the flame sensor wont get a reading and wont fire.

davesparks · Aug 4, 2023

oscar21 said:
Even if it does say L&N it still makes no difference,

Yes it does as any fuses or similar protection will be in the L path within the equipment.

kropaske · Aug 5, 2023

Surely that is not the case. While UK have polarised sockets most EU does not, so any devices with the plug must be designed in such a way to be safe either way they are connected, unless they are hardwired and manual specify how to connect it.

mainline · Aug 5, 2023

oscar21 said:
Even if it does say L&N it still makes no difference, there is no way for any electrical product to know which way round the AC is connected if its just a two wire connector.

Not true, even a non-contact pen proves otherwise.

Pretty Mouth · Aug 5, 2023

davesparks said:
Yes it does as any fuses or similar protection will be in the L path within the equipment.

For equipment that has no connection to earth, why might reverse polarity be an issue? What I mean is, if a fuse isn't for earth fault protection, it would be for overcurrent protection: opening the circuit anywhere would deal with the overcurrent problem.

What further problems could occur if the N was open rather than the L? (Not disputing what you're saying BTW, just asking). The only equipment like this that I can think of that would be a problem reverse polarity would be class II ES lampholders.

mainline · Aug 5, 2023

Pretty Mouth said:
For equipment that has no connection to earth, why might reverse polarity be an issue? What I mean is, if a fuse isn't for earth fault protection, it would be for overcurrent protection: opening the circuit anywhere would deal with the overcurrent problem.

What further problems could occur if the N was open rather than the L? (Not disputing what you're saying BTW, just asking). The only equipment like this that I can think of that would be a problem reverse polarity would be class II ES lampholders.

It will depend on where the reverse polarity occurs.
If it’s at the supply end for instance the cable will remain live as will the item.

oscar21 · Aug 5, 2023

davesparks said:
Yes it does as any fuses or similar protection will be in the L path within the equipment.

How will the fuse or driver know which way round its connected though, there wont be any earth present so its just two live wires with 230V across them, both are live with respect to each other 50 times a second, there isn't any live or neutral as far as the driver is concerned.

Pretty Mouth · Aug 5, 2023

mainline said:
It will depend on where the reverse polarity occurs.
If it’s at the supply end for instance the cable will remain live as will the item.

Understood, but in the context of post #8 we're talking about reversing the wiring at the equipment rather than the upstream circuit

oscar21 · Aug 5, 2023

mainline said:
Not true, even a non-contact pen proves otherwise.

I'm not too sure how those pens work but I assume you are creating a path to earth for it when you hold it, much like a neon screwdriver. Live and neutral are both at 230V relative to each other, its only because one side is tied to earth that it becomes the neutral, you could tie the other side of the supply to earth instead and that would then become the neutral.

timhoward · Aug 5, 2023

I sense cross purposes here. Post 8 is actually more specific than it appears at first glance.

But in terms of cross polarity equipment with no earth, integral switching could make it unsafe.
A integral fuse one the ‘return’ could leave things more dangerous for anyone (unwisely) working on it live.

In most cases, if equipment isn’t marked it isn’t gear I want to be using anyway!

mainline · Aug 5, 2023

oscar21 said:
I'm not too sure how those pens work but I assume you are creating a path to earth for it when you hold it, much like a neon screwdriver. Live and neutral are both at 230V relative to each other, its only because one side is tied to earth that it becomes the neutral, you could tie the other side of the supply to earth instead and that would then become the neutral.

The pen would still only work on the L side whether that’s the chassis or not.

Maybe a socket tester would be a better example

mainline · Aug 5, 2023

Pretty Mouth said:
Understood, but in the context of post #8 we're talking about reversing the wiring at the equipment rather than the upstream circuit

Even a class 2 enclosure circuit could rely on the polarity having to be correct as a fault could make the o/p L instead of N it would have to be a pretty crap circuit for that to happen though.

littlespark · Aug 6, 2023

Let’s just say that some appliances, it doesn’t matter…. On others it does…. For whatever reason.

Radios tvs etc with a figure 8 cable plug can be put in either way… so doesn’t matter there….

Other things, if marked L and N, must be for a reason.

The LED driver in the OP is unmarked, so either way would be possible.

I seem to think the Ring video doorbells are the same? ELV, but still AC from a transformer.
Only 2 connections, and no markings whatsoever.

~

~

~

~

~

~

~

davesparks

~

~

~

~

~

~

~

~

~

~

~

Share this page to anywhere at all

Similar threads

OFFICIAL SPONSORS

Advert

Daily, weekly or monthly email

Thread starter

Thread Information

Thread Tags

Advert

Thread statistics

Advert