Sorry, when he said "The chassis was connected to a 2 pin AC plug", I=20
took it to mean the neutral was tied to the chassis.  If it is not then=20
there is no problem with tying the ground to the chassis.

Kerry

On 7/11/2014 12:06 PM, Dwayne Reid wrote:
> Kerry - what you wrote about is not what was described.  The supply
> has a 2-wire AC input which is NOT connected to the output in any
> way.  The output DC common is connected to the chassis.  This is
> common practise.
>
> dwayne
>
> At 11:04 AM 7/11/2014, Kerry wrote:
>> I don't know if it's 'standard practice' or not, but it shouldn't be.
>> If the neutral and ground are tied together in the device, then there
>> will be current through the ground wire.  There should NEVER be current
>> through the ground wire during normal operation.  It will also trip a
>> GFI type device if one is used.  DC common should be to neutral and the
>> chassis to ground.
>>
>>
>> On 7/11/2014 10:29 AM, Justin Richards wrote:
>>> Basically my question is, Is it standard practice to tie the SMPS DC gr=
ound
>>> to the mains earth?
>>>
>>> I am re-using a metal case and its built in SMPS from a faulty digital =
TV
>>> decoder to house the PI(D) oven controller.
>>>
>>> The chassis was connected to a 2 pin AC plug and as such was not earthe=
d
>>> and the 0V/GND of the SMPS was tied to the chassis.  (I thought such a
>>> device either has to be earthed or double insulated.)
>>>
>>> I have installed an IEC socket and IEC plug and about to connect all th=
e
>>> earths to the metal chassis but noticed the DC ground is currently also
>>> tied to the chassis.  I assume this is standard practice but cant
>>> definitely recall if I have seen a device wired this way.
>>>
>>> Justin
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