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Home > Archive > Electrical Engineering > February 2007 > Mains powered plug-in enclosure
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Mains powered plug-in enclosure
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| Hello, I'm working on a mains powered design and am having
difficulties finding a wall plugin 'shell' to use for my design. I
would like to place a custom PCB inside the wall plugin (picture a
cell phone charger, and cut the cord) and have my circuit mains
powered. My circuit will require around 300mA at 3.3VDC. Any
suggestions? Would something like this have to go through UL certs if
I find the ACtoDC converter in an enclosure that is already UL
certified?
Thank you in advance!
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| gfretwell@aol.com 2007-02-27, 3:25 am |
| On 26 Feb 2007 20:55:07 -0800, "teaks" <mark.tekippe@gmail.com> wrote:
>Hello, I'm working on a mains powered design and am having
>difficulties finding a wall plugin 'shell' to use for my design. I
>would like to place a custom PCB inside the wall plugin (picture a
>cell phone charger, and cut the cord) and have my circuit mains
>powered. My circuit will require around 300mA at 3.3VDC. Any
>suggestions? Would something like this have to go through UL certs if
>I find the ACtoDC converter in an enclosure that is already UL
>certified?
>
>Thank you in advance!
U/L certification is the main reason why you have so many wall warts
behind your PC. Designing and getting a mains powered device NRTL
tested will gobble up a huge part of your potential profits. It is
easier for a designer to start with low voltage DC from an already
listed supply.
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| Ben Miller 2007-02-27, 3:25 am |
| "teaks" <mark.tekippe@gmail.com> wrote in message
news:1172552107.853333.98170@p10g2000cwp.googlegroups.com...
> Hello, I'm working on a mains powered design and am having
> difficulties finding a wall plugin 'shell' to use for my design. I
> would like to place a custom PCB inside the wall plugin (picture a
> cell phone charger, and cut the cord) and have my circuit mains
> powered. My circuit will require around 300mA at 3.3VDC. Any
> suggestions? Would something like this have to go through UL certs if
> I find the ACtoDC converter in an enclosure that is already UL
> certified?
>
> Thank you in advance!
>
If you use a UL listed low voltage power supply, and your device is in a
separate enclosure so it only sees low voltage, then you will probably not
need UL listing on your device. However, if you mount your circuit board
inside the plug-in housing, you will need to get the finished product UL
listed. Even if you use a listed converter, as soon as you open it and
install your components you void the previous listing. Of course, not
knowing what your product is, I should point out that there may still be
other agency approvals necessary.
Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
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| billb@abc.net 2007-02-27, 5:25 pm |
| When will you guys in the USA learn that you do not need a UL approval any
more for the USA, what you need is a NRTL approval, where the product has
been tested to UL standard, but not a UL approval.
We moved away from this in Europe years ago, we now only look for an
approval from a European Nationally recognised approval body.
For example if you wanted TUV to approve a piece of IT equipment, they would
look for components approvals from a European Approval Body, this could be
BSI, DEMKO, NF, VDE etc. This makes life much easier when you are designing
a new product and need to source components.
BillB
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| Ben Miller 2007-02-27, 5:25 pm |
| <billb@abc.net> wrote in message
news:TR%Eh.23799$tz6.3230@newsfe2-gui.ntli.net...
> When will you guys in the USA learn that you do not need a UL approval any
> more for the USA, what you need is a NRTL approval, where the product has
> been tested to UL standard, but not a UL approval.
> We moved away from this in Europe years ago, we now only look for an
> approval from a European Nationally recognised approval body.
> For example if you wanted TUV to approve a piece of IT equipment, they
> would
> look for components approvals from a European Approval Body, this could be
> BSI, DEMKO, NF, VDE etc. This makes life much easier when you are
> designing
> a new product and need to source components.
>
> BillB
True, to be accurate it can have any NRTL mark, such as ETL, but that will
still imply the same requirements for the product. Nothing changes with
regard to the OP query, other than the name of the lab.
Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
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| billb@abc.net 2007-02-27, 5:25 pm |
| I'm glad to hear you agree, but everyone seems to only think in terms of a
UL approval.
In the UK clients complain about the service they get from UL, but still
keep going back for more.
It's time more people realised that any of the NRTL can issue approval as
long as they are accredited for the standard involved.
Some clients in the UK come to us for a CB test report and certificate and
then apply for a UL approval using our CB certificate and report, they tell
me it reduces the time to get an approval from UL.
We could issue a NRTL approval in the USA for them, without the extra cost
of a CB report and certificate and in less than half the time it will take
them to get a UL approval.
When we ask them why they keep using UL the answer is always their clients
in the USA is asking for a UL approval.
BillB
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| Tom Horne, Electrician 2007-02-28, 3:25 am |
| billb@abc.net wrote:
> I'm glad to hear you agree, but everyone seems to only think in terms of a
> UL approval.
> In the UK clients complain about the service they get from UL, but still
> keep going back for more.
> It's time more people realised that any of the NRTL can issue approval as
> long as they are accredited for the standard involved.
>
> Some clients in the UK come to us for a CB test report and certificate and
> then apply for a UL approval using our CB certificate and report, they tell
> me it reduces the time to get an approval from UL.
> We could issue a NRTL approval in the USA for them, without the extra cost
> of a CB report and certificate and in less than half the time it will take
> them to get a UL approval.
> When we ask them why they keep using UL the answer is always their clients
> in the USA is asking for a UL approval.
>
> BillB
Bill
That may make sense given the origin of the name "Underwriters
Laboratories." The original UL was a loft building in Chicago were an
engineer hired by the insurance underwriters for the great Chicago
Exposition set up his shop. The fires caused by the inadequate parts
being used to install the brand new electric lights for the exposition
had killed two of the first due fire companies horses by exhaustion.
After the underwriters forced all of the installers to submit samples to
their engineer the exposition came off with far fewer problems then the
construction phase would have suggested.
There may still be insurance carriers that will only except the UL
label. The counterpart in the mutual insurance companies was the
factory mutual approval process. UL served the stock companies and FM
served the mutual insurers.
The other problem we have here is that UL has become the Kleenex or
Zerox of testing laboratories. Their customer may be saying UL when
they only mean NRTL listed.
--
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison
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| Ben Miller 2007-02-28, 1:25 pm |
| "Tom Horne, Electrician" <hornetd@mindspring.com> wrote in message
news:Vs8Fh.7275$tD2.5633@newsread1.news.pas.earthlink.net...
> Bill
> That may make sense given the origin of the name "Underwriters
> Laboratories." The original UL was a loft building in Chicago were an
> engineer hired by the insurance underwriters for the great Chicago
> Exposition set up his shop. The fires caused by the inadequate parts
> being used to install the brand new electric lights for the exposition had
> killed two of the first due fire companies horses by exhaustion. After the
> underwriters forced all of the installers to submit samples to their
> engineer the exposition came off with far fewer problems then the
> construction phase would have suggested.
Wow, you learn something new every day. I never knew that history. Back in
the 70's I used to work a block away from the then UL Chicago headquarters,
which was a small multi-story building on the near north side, not far from
Navy Pier. The building had winding staircases with brass railings. Perhaps
the same building? I called on them often working on our product approvals.
They closed that building down years ago. I now work less than a mile from
their Northbrook, IL main headquarters. It is just a bit bigger!
Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
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