LED Shower Niche

[morg]

Hi, I've just had an email back from Thermopanel,

They are saying the LED is rated IP67.

 

[morqthana]

Did they say where you should install the power supply, given that it needs to be in an enclosure but also needs cooling by free air, it can't go in Zone 1 and it needs re-testing and re-certifying for EMC compliance?

Looks like something thrown together from parts with no consideration as to how the whole assembly is supposed to comply with any known standards.

 

[morg]

Hi, I didn't ask about the driver location.

But as you say the meanwell datasheet states "Cooling by free air convection"

That said I guess that means all LED drivers shouldn't be stuffed in the ceiling void, but I bet most are installed in the ceiling void or some other air tight location.

So basically the proper way would be mount this box/driver outside the bathroom i.e the landing ceiling or top of wall to allow airflow / heat dissipation

Power Supply Enclosure for Meanwell LED Power Supply | LEDSpace

This power supply enclosure is used in conjunction with our LED Drivers to secure it to surfaces. They also protect the driver and enclose the live terminals, making it a necessary purchase where the driver may be exposed. Four holes are drilled either side of the enclosure for wiring. Not...

www.ledspace.co.uk

Does anyone actually install this box? Probably not.

But I do like the idea of a vented enclosure instead of an access panel

 

[morqthana]

But as you say the meanwell datasheet states "Cooling by free air convection"

That said I guess that means all LED drivers shouldn't be stuffed in the ceiling void, but I bet most are installed in the ceiling void or some other air tight location.

Ceiling voids aren't air tight.

So basically the proper way would be mount this box/driver outside the bathroom i.e the landing ceiling or top of wall to allow airflow / heat dissipation

Power Supply Enclosure for Meanwell LED Power Supply | LEDSpace

This power supply enclosure is used in conjunction with our LED Drivers to secure it to surfaces. They also protect the driver and enclose the live terminals, making it a necessary purchase where the driver may be exposed. Four holes are drilled either side of the enclosure for wiring. Not...

www.ledspace.co.uk

It's quite neat looking, but do you want it on show?

Does anyone actually install this box? Probably not.

No - probably not. It's rather expensive for a plastic enclosure that size.

People have been putting supplies like that above ceilings without enclosures for years, and ones putting out 10x as much power when sold for halogen lighting, to no ill effect. They too would have contravened the manufacturers instructions on EMC compliance.

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I've been giving Thermopanel a hard time because they ought to have done a better job of designing and manufacturing an integrated product, not just sourcing a collection of components to turn their plain shelves into illuminated ones and leaving their customers to figure out how to install it all.

If it were me, I'd fix the supply to a ceiling joist and put a junction box hard up against it to enclose the unsheathed mains cables.

 

[endecotp]

But as you say the meanwell datasheet states "Cooling by free air convection"

It's a 12W power supply. If it's 60% efficient, that means it is dissipating 8W itself. (It should be better than that.) That's not a lot of heat.

It claims max ta = 45C (ambient temperature?) and tc = 75C (case temperature?).

With those numbers, I don't think it needs any particular provision for air flow. If you're concerned, run it for a few minutes wrapped up in some fibreglass insulation and measure the case temperature.

 

[endecotp]

If it were me, I'd fix the supply to a ceiling joist and put a junction box hard up against it to enclose the unsheathed mains cables.

If it were me, I'd investigate opening it up and replacing the existing unsheathed wires with T&E.

I wouldn't necessarily recommend that for others though!

 

[ebee]

In my day I have seen quite a few potential hotspots create problems such as open top tungsten halogen fittings 50W and absolutely packed tight with insulation causing the bog standard strip connectors to melt and cause problems, actually I`ve been rather surprised on how long they actually lasted after the insulation had been applied - plumbers wire some fittings in the cavity then a few weeks later same fir of plumbers adds the insulation and crams it in on one occasion , no regard for either operation or both operations in unison, it beggars belief, well it should do but it didn`t !!!

Another example, builder advised to get forward beam diachronic reflectors on 12v T/H lighting but gets mains ones cos they cheaper and wholesalers advise him to use plant pots inverted to cover and protect from insulation, well he gets plastic tubs alright, margarine tubs and with not much space for air to flow either.

 

[morqthana]

It's a 12W power supply. If it's 60% efficient, that means it is dissipating 8W itself. (It should be better than that.)

Assuming that 0.35A is the worst case, i.e. with an input voltage of 100V, doesn't this mean that it consumes 35W for an output of 12W?

 

[morqthana]

If it were me, I'd investigate opening it up and replacing the existing unsheathed wires with T&E.

I'd be amazed if the case could be (non-destructively) opened

 

[SUNRAY]

Assuming that 0.35A is the worst case, i.e. with an input voltage of 100V, doesn't this mean that it consumes 35W for an output of 12W?

View attachment 390980

I'd be amazed if a SMPS typically stated as efficiency of 82% could run at 34% efficient or even that any SMPS could be designed and/or built to be only 34% efficient.

 

[morqthana]

I'd be amazed if a SMPS typically stated as efficiency of 82% could run at 34% efficient or even that any SMPS could be designed and/or built to be only 34% efficient.

Well, yeah, but the maker's spec sheet does say:

Also, having watched a number of Big Clive's videos I'm no longer amazed at how shoite some products can be.

 

[endecotp]

Assuming that 0.35A is the worst case, i.e. with an input voltage of 100V, doesn't this mean that it consumes 35W for an output of 12W?

I think you should consider 0.35A as worst-case as in brief inrush current, or something like that. I.e. don’t fit an upstream fuse of less than that.

Edit: I see that the inrush is 70A for a few microseconds. I can’t really explain under what circumstances it might take 0.35A.

 

[endecotp]

I'd be amazed if a SMPS typically stated as efficiency of 82% could run at 34% efficient or even that any SMPS could be designed and/or built to be only 34% efficient.

It can do if the load is low; the quoted efficiency is at full load.

If you’re running at half load, you’re losing the same amount of power in the gate capacitance of the MOSFET as at full power; other components are similar. The moral is not to use power supplies that are substantially larger than needed.

 

[SUNRAY]

Well, yeah, but the maker's spec sheet does say:

View attachment 390986

Also, having watched a number of Big Clive's videos I'm no longer amazed at how shoite some products can be.

But this is a MeanWell product, not some eebyjeeby parc from Aliexpress.

 

[SUNRAY]

It can do if the load is low; the quoted efficiency is at full load.

If you’re running at half load, you’re losing the same amount of power in the gate capacitance of the MOSFET as at full power; other components are similar. The moral is not to use power supplies that are substantially larger than needed.

Yes totally accepted, if taken to the 'no load' situation the efficiency has to be zero by simple definition. I did go through some experimentation a while back when a previous member insisted the efficiency of SMPSs was constant across input voltages. I don't believe I kept a no load record but do recall it was very dependant on supply voltage.