Author Topic: MH PAR lamp uplight  (Read 236 times)
sol
Hero Member
*****
Offline

Posts: 607
View Gallery

MH PAR lamp uplight « on: January 07, 2017, 09:36:27 PM » Author: sol
I'm currently prototyping an uplight that is 35W CDM PAR (I forget the angle at the moment). It is an older Philips Powertone lamp. Question is would you operate this lamp naked for an uplight ? I'm considering an open top enclosure, maybe an old tin can or a galvanized bucket. I've seen countless such lamps in downlight applications but I am wondering about uplighting. I'm not worried about the actual operating of the lamp, just should dust settle on the surface, or a fly dies on the surface, or a piece of paper falls there. I measured mine after a few hours of operation with an infrared thermometer and got a reading of about 111 degrees Celcius.

Thanks for any input.
Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3523
View Gallery

Re: MH PAR lamp uplight « Reply #1 on: January 08, 2017, 10:05:51 AM » Author: Medved
These are designed for open fixture, so should be fine.
110degC should not cause any problem at all (well, except thermal shock from water or ice, so open rated only indoors), most naked incandescents are way hotter than that.

Of course, when you expect a lot of flying paper pieces or other dust (e.g. wood shop,...), then we are not talking about a normal indoor environment anymore, but about an hazardous environment with the combustible dust hazard. And for that you would need the whole installation to be explosion dust proof. But such conditions are not supposed to be present at normal home...
Logged

No more selfballasted c***

Ash
Hero Member
*****
Offline

Posts: 2780
View Gallery


Re: MH PAR lamp uplight « Reply #2 on: January 08, 2017, 10:16:30 AM » Author: Ash
Actually, why not ? What prevents dust from accumulating on the lamp face over 20 years, or the user for not using the lamp and then switching it on for the 1st time in 20 years ?
Logged
sol
Hero Member
*****
Offline

Posts: 607
View Gallery

Re: MH PAR lamp uplight « Reply #3 on: January 08, 2017, 10:16:51 AM » Author: sol
Thank you for the reassurance. An occasionnal pass of the vacuum cleaner should take care of it.
Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3523
View Gallery

Re: MH PAR lamp uplight « Reply #4 on: January 12, 2017, 03:16:58 AM » Author: Medved
Actually, why not ? What prevents dust from accumulating on the lamp face over 20 years, or the user for not using the lamp and then switching it on for the 1st time in 20 years ?

That is called neglected maintenance. I'm not aware about any technology, which will remain safe even when the maintenance is so heavily neglected, which would be still safe. Include a small tent...
Logged

No more selfballasted c***

Ash
Hero Member
*****
Offline

Posts: 2780
View Gallery


Re: MH PAR lamp uplight « Reply #5 on: January 12, 2017, 01:44:24 PM » Author: Ash
You have to expect this, especially in devices meant for home use. Why would anyone even guess that they have to wipe dust on top of a "white box that does nothing" installed in an "unreachable location" above a flight of stairs ?
Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3523
View Gallery

Re: MH PAR lamp uplight « Reply #6 on: January 13, 2017, 11:06:38 AM » Author: Medved
The standard incandescents are way greater problem with this aspect, yet the problem is apparently not that bad in normal home environments.
Don't forget usually there is quite some air movement around any such small exposed things, which prevents buildup of really high amount of dust, unless there is an excessive amount of it in the air (a wood working shop, theaters,...).
Normally (at homes,...) the dust is only on the bulb, so even if some collects there, it just causes a bit of burning smell, but nothing really dangerous.
But when there is a huge amount of dust flying in the air, the smouldering/burning may easily spread over the air and cause a real dangerous dust explosion (I remember one from the 80's - city theater roof just blew off the building, when the janitor just turned ON some side lights...).
Logged

No more selfballasted c***

Ash
Hero Member
*****
Offline

Posts: 2780
View Gallery


Re: MH PAR lamp uplight « Reply #7 on: January 13, 2017, 01:24:01 PM » Author: Ash
i'd think what makes the difference is the power density : Dust directly on the lamp surface, or on a Glass panel with bigger surfce area (so lower temperature)

The dangerous conditions i see are -

if the thing is a lamp with a "classic" paper lampshade or next to curtains, with distance from lamp to fuel which is normally safe enough to not get ignited by the lamp directly, but if there is dust/cobwebs/... on the lamp then this can ignite first and then set fire to the bigger fuel

if something up there can burn for more than a second (something caught in cobwebs ?), so can fall or fly while still burning (like a teabag on fire), and land somewhere else



The flying roof is something i'd expect to see with one of Team Rocket's machines, not in a theater building.. Wow

But ! Was that caused by heat from a lamp ? If the explosion happened immediately at switch on, i'd think it was ignited by some arc (from a short circuit or bad connection, open because somebody connected without a box) and not from heat output of a lamp
Logged
sol
Hero Member
*****
Offline

Posts: 607
View Gallery

Re: MH PAR lamp uplight « Reply #8 on: January 13, 2017, 02:39:35 PM » Author: sol
Well my home is not that dusty so I wouldn't think anything to such extreme would happen. Should a very slight accumulation of dust occur, I would imagine you would smell a bit of "heated substance" similar to an electric heater that hasn't been used for a while.
Logged
wattMaster
Hero Member
*****
Online

Gender: Male
Posts: 1782
View Gallery

Lit With CFL


Re: MH PAR lamp uplight « Reply #9 on: January 13, 2017, 08:35:12 PM » Author: wattMaster
I would probably make an enclosure for the lamp to stop dust.
Logged

Where are daylight fluorescents when you need them?

Print 
© 2005-2017 Lighting-Gallery.net | Powered by SMF 1.1.21 | SMF © 2015, Simple Machines