Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.


aucklander

477 posts

Ultimate Geek


#136770 8-Dec-2013 16:20
Send private message

Hi there,
considering even a modest PSU is rated 15-18A for the 12V DC rail (and maybe 40A for the 5V DC rail), I wonder why I do not hear more about these being used for exterior lighting? They are mass produced, which means they are cheap to get or to replace. They are fairly reliable and I would say safe (I did not hear about a house fire started by a PSU yet). They have internal cooling and if they overheat, they will shutdown.

As long as it is installed indoors (garage? workshop?) then all looks OK to me. They plug into a power point and the wiring on low voltage is not prescribed work, so you can do whatever you want without needing an electrician. Of course you need to have common sense and use properly sized cables, fuses switching gear and such, but otherwise I do not see a downside?

what do you think?

Secondly, why are not the isolating transformers more often used for garden lights? You can get then lots of power (and light) safely, while using standard fittings and bulbs (cheaper). With an isolating transformer there is no way you can get an electric shock (this is why they were created). You can easily get 1kW or 2kW isolating transformers. Not entirely sure if this requires an electrician (it is mains voltage, but at the same time safe?). This is just an idea... but the PSU thing looks doable!




mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.


View this topic in a long page with up to 500 replies per page Create new topic
 1 | 2 | 3
gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #947536 8-Dec-2013 16:42
Send private message



I think you should look up perscribed electrical work 1st, it covers a lot more than you may think.




richms
28168 posts

Uber Geek

Trusted
Lifetime subscriber

  #947573 8-Dec-2013 17:57
Send private message

Till recently outdoor lighting has been all halogen so needed ac to not have lousy lamp life. And long cables meant it had to be low frequency so no nice electronic transformers.

An open frame 12v power supply isn't much more than a quality desktop pc power supply and doesn't have all the needless 5v stuff in it. Those get used extensively now that led is the norm for outdoor lighting.

There are still places you want a selv power supply like pool lights and water features so a common old magnetic transformer still gets used there.




Richard rich.ms

aucklander

477 posts

Ultimate Geek


  #947587 8-Dec-2013 18:26
Send private message

Hi gregmcc,

do you suggest that 12V wiring is prescribed electrical work? I would like to look it up, could you please point me into the right direction where to look for clarifications? Many thanks.

I also know there is a document which lists what a homeowner can do even if mains voltage fixed wiring is involved. Does that help at all?




mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.




gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #947607 8-Dec-2013 19:20
Send private message

aucklander: Hi gregmcc,

do you suggest that 12V wiring is prescribed electrical work? I would like to look it up, could you please point me into the right direction where to look for clarifications? Many thanks.

I also know there is a document which lists what a homeowner can do even if mains voltage fixed wiring is involved. Does that help at all?


here is the link for the legislation describing prescribed electrical work.

Your out clause may have been 2 (b) (i), but as the PSU is 230V that makes it low voltage which is higher than the extra-low voltage, so thus it is perscribed electrical work.

stevenz
2802 posts

Uber Geek


  #948198 9-Dec-2013 16:22
Send private message

The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?






gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #948206 9-Dec-2013 16:31
Send private message

stevenz: The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?




That would be correct, building your own PC (if it includes the PSU) is perscribed electrical work.

There are quite a number of calculations that need to be done to work out the correct loading, fitting the correct protection devices to the load side and so on, unless you have the required formal training there is virtually no way it can be safely done.

A lot of computer shops know this already and some of their techs may already have the right kind of registration to legally be able to do this, some shops don't and they know it but would rather play dumb and try and get away with it.

fastmikey
287 posts

Ultimate Geek

ID Verified

  #948518 10-Dec-2013 10:07
Send private message

gregmcc:
stevenz: The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?




That would be correct, building your own PC (if it includes the PSU) is perscribed electrical work.

There are quite a number of calculations that need to be done to work out the correct loading, fitting the correct protection devices to the load side and so on, unless you have the required formal training there is virtually no way it can be safely done.

A lot of computer shops know this already and some of their techs may already have the right kind of registration to legally be able to do this, some shops don't and they know it but would rather play dumb and try and get away with it.


Sorry to be pedantic, but doesn't 1 c) blow that out of the water? Assembling a PC doesn't (generally) involve more with electrical wiring then plugging connections together...

 
 
 

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.
gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #948591 10-Dec-2013 11:44
Send private message

fastmikey:
gregmcc:
stevenz: The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?




That would be correct, building your own PC (if it includes the PSU) is perscribed electrical work.

There are quite a number of calculations that need to be done to work out the correct loading, fitting the correct protection devices to the load side and so on, unless you have the required formal training there is virtually no way it can be safely done.

A lot of computer shops know this already and some of their techs may already have the right kind of registration to legally be able to do this, some shops don't and they know it but would rather play dumb and try and get away with it.


Sorry to be pedantic, but doesn't 1 c) blow that out of the water? Assembling a PC doesn't (generally) involve more with electrical wiring then plugging connections together...



The computer as a whole box is an appliance and 1 (c) would apply, but the PSU as an internal component of that appliance would not, the PSU is desgined to be mounted and contained with a PC case, it is not desgined for use as a stand alone unit, as it is desgined as a component that operates at low voltage >50VAC to <1000VAC then any work done on a component that operates at low voltage is perscribed electrical work

Fred99
13684 posts

Uber Geek


  #948614 10-Dec-2013 11:53
Send private message

fastmikey:
gregmcc:
stevenz: The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?




That would be correct, building your own PC (if it includes the PSU) is perscribed electrical work.

There are quite a number of calculations that need to be done to work out the correct loading, fitting the correct protection devices to the load side and so on, unless you have the required formal training there is virtually no way it can be safely done.

A lot of computer shops know this already and some of their techs may already have the right kind of registration to legally be able to do this, some shops don't and they know it but would rather play dumb and try and get away with it.


Sorry to be pedantic, but doesn't 1 c) blow that out of the water? Assembling a PC doesn't (generally) involve more with electrical wiring then plugging connections together...


That's how I'd see it too, the PSU unit in an enclosed separate case with plug-in power cord, AS/NZS approved, protection circuits already in place, the technician only ever dealing with the "extra-low voltage" out, not significantly different from plugging in a laptop charger or connecting a car battery charger to a a battery etc.  But opening up the PSU would be a different story, presumably the same requirements as for appliance service people requiring limited electrical registration.  The work installing or replacing a PSU on a PC can be done without "without exposure to live parts intended to operate at voltages exceeding extra-low voltage" so should not be prescribed electrical work.

Fred99
13684 posts

Uber Geek


  #948617 10-Dec-2013 11:59
Send private message

gregmcc:
fastmikey:
gregmcc:
stevenz: The voltage supply itself is only 12V, the input _to_ the supply from a standard IEC lead is 230/240V. 

If that's not ok, then would that also suggest that building your own PC would be prescribed work as you're working with a 230V PSU supplying 12V hardware?




That would be correct, building your own PC (if it includes the PSU) is perscribed electrical work.

There are quite a number of calculations that need to be done to work out the correct loading, fitting the correct protection devices to the load side and so on, unless you have the required formal training there is virtually no way it can be safely done.

A lot of computer shops know this already and some of their techs may already have the right kind of registration to legally be able to do this, some shops don't and they know it but would rather play dumb and try and get away with it.


Sorry to be pedantic, but doesn't 1 c) blow that out of the water? Assembling a PC doesn't (generally) involve more with electrical wiring then plugging connections together...



The computer as a whole box is an appliance and 1 (c) would apply, but the PSU as an internal component of that appliance would not, the PSU is desgined to be mounted and contained with a PC case, it is not desgined for use as a stand alone unit, as it is desgined as a component that operates at low voltage >50VAC to <1000VAC then any work done on a component that operates at low voltage is perscribed electrical work


That's fair enough, I suppose there's risk from a PSU in usually heavily perforated case if it was used for the OP's suggested purpose, and just left somewhere where it could be exposed to water, kids poking knitting needles in to it or whatever.
I'm sure Jaycar etc will sell either transformer or switchmode based PSU made for the intended purpose.

fastmikey
287 posts

Ultimate Geek

ID Verified

  #948854 10-Dec-2013 17:18
Send private message

gregmcc: The computer as a whole box is an appliance and 1 (c) would apply, but the PSU as an internal component of that appliance would not, the PSU is desgined to be mounted and contained with a PC case, it is not desgined for use as a stand alone unit, as it is desgined as a component that operates at low voltage >50VAC to <1000VAC then any work done on a component that operates at low voltage is perscribed electrical work


Oh, I'm not disagreeing there, but computer shops assembling PCs are exempted under 1 (c). Just don't want to see any SME business owners unduly freaking out 

gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #948861 10-Dec-2013 17:49
Send private message

fastmikey:
gregmcc: The computer as a whole box is an appliance and 1 (c) would apply, but the PSU as an internal component of that appliance would not, the PSU is desgined to be mounted and contained with a PC case, it is not desgined for use as a stand alone unit, as it is desgined as a component that operates at low voltage >50VAC to <1000VAC then any work done on a component that operates at low voltage is perscribed electrical work


Oh, I'm not disagreeing there, but computer shops assembling PCs are exempted under 1 (c). Just don't want to see any SME business owners unduly freaking out 


And I would disagree there, 1 (C) is reffering to appliances, such as your jug or toaster or fully assembled PC, as soon as the cover comes off the PC then you are now preforming a servicing or assembling task, when the PSU is removed (or installed), remembering that clause 2 goes on to describe exacty what is not perscribed work and assembling a PC PSU in to a case or using it in another manor does not fall in to the defination of none perscribed work.

You just can't pick out 1 clause of the regs and say look that clause seems to fit what I think so it must be so, a full and complete understanding of all the regulations is required, and when a particular reg quite clearly defines what is not perscribed work as in clause 2


Fred99
13684 posts

Uber Geek


  #948863 10-Dec-2013 17:54
Send private message

IMO, there's a much more serious issue here - from the original post:
"With an isolating transformer there is no way you can get an electric shock (this is why they were created)"

Fred99
13684 posts

Uber Geek


  #948873 10-Dec-2013 18:08
Send private message

13.8V DC 20A switchmode benchtop PSU, for $119.00

http://www.jaycar.co.nz/productView.asp?ID=MP3078&form=CAT2&SUBCATID=999#3

D
o anything you like with the 13.8V out - it's not subject to any electrical reg.
Much less mucking around than trying to adapt a computer PSU.

gregmcc
2147 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #948875 10-Dec-2013 18:09
Send private message

Fred99: IMO, there's a much more serious issue here - from the original post:
"With an isolating transformer there is no way you can get an electric shock (this is why they were created)"


Been quite honest here, this is the kind of thing that someone who thinks they know what they are doing, but doesn't says.

A little knowledge is a dangerious thing, this is why the electrical industry is heavily regulated.



 1 | 2 | 3
View this topic in a long page with up to 500 replies per page Create new topic





News and reviews »

Air New Zealand Starts AI adoption with OpenAI
Posted 24-Jul-2025 16:00


eero Pro 7 Review
Posted 23-Jul-2025 12:07


BeeStation Plus Review
Posted 21-Jul-2025 14:21


eero Unveils New Wi-Fi 7 Products in New Zealand
Posted 21-Jul-2025 00:01


WiZ Introduces HDMI Sync Box and other Light Devices
Posted 20-Jul-2025 17:32


RedShield Enhances DDoS and Bot Attack Protection
Posted 20-Jul-2025 17:26


Seagate Ships 30TB Drives
Posted 17-Jul-2025 11:24


Oclean AirPump A10 Water Flosser Review
Posted 13-Jul-2025 11:05


Samsung Galaxy Z Fold7: Raising the Bar for Smartphones
Posted 10-Jul-2025 02:01


Samsung Galaxy Z Flip7 Brings New Edge-To-Edge FlexWindow
Posted 10-Jul-2025 02:01


Epson Launches New AM-C550Z WorkForce Enterprise printer
Posted 9-Jul-2025 18:22


Samsung Releases Smart Monitor M9
Posted 9-Jul-2025 17:46


Nearly Half of Older Kiwis Still Write their Passwords on Paper
Posted 9-Jul-2025 08:42


D-Link 4G+ Cat6 Wi-Fi 6 DWR-933M Mobile Hotspot Review
Posted 1-Jul-2025 11:34


Oppo A5 Series Launches With New Levels of Durability
Posted 30-Jun-2025 10:15









Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.