How common is this?

[Canuck57]

I was replacing the belt on a Denon DVD-2900 CD/SACD player and noticed that the ground prong in the 3-prong female power socket on the back of the unit was not internally wired to anything inside the unit. I'm assuming it passed an electrical certification as internally it's double insulated. Go easy on me, I'm an accountant not an electrical engineer.

 

[JustJones]

I think it has to do with preventing possible ground loops. The DVD or CD player is grounded through the interconnects to the preamp or integrated amp, most I've seen are like yours which isn't a lot just ones I've owned, the earth ground isn't connected to the chassis. Someone who knows more than I do will come along and explain it better. Here's a photo of another 2900

 

[sam_adams]

I was replacing the belt on a Denon DVD-2900 CD/SACD player and noticed that the ground prong in the 3-prong female power socket on the back of the unit was not internally wired to anything inside the unit.

A device that is double-insulated would not necessarily have an internal EGC safety ground connection to the chassis. Normally, you would see the IEC connector on the device with only two prongs—the EGC prong would be missing— and there would be labelling on the device indicating it is double insulated:

the little square-in-a-square as indicated.

The device you have probably pre-dates those labelling requirements or was from a region that did not require them at the time of manufacture.

 

[Blumlein 88]

Having double insulation and no safety ground is very common in AV components.

 

[Canuck57]

Having double insulation and no safety ground is very common in AV components.

Yes it is common, however it seems deceiving to the customer to have a three-prong power cord connection when there is no grounding of the unit. My unit was made in China, December 2003 and does not have the double insulated symbol but a UL certification.

 

[Blumlein 88]

Yes it is common, however it seems deceiving to the customer to have a three-prong power cord connection when there is no grounding of the unit. My unit was made in China, December 2003 and does not have the double insulated symbol but a UL certification.

Maybe, but it does not matter. Most stuff has the same plug in the back with only 2 prongs. Having three and nothing connected is the same thing. Is there something people expect from that 3rd pin which isn't connected that they don't get? The item is safe in same way.

 

[Canuck57]

I assume it's cheaper for the manufactuer to install the three-prong female IEC receptable on the back of all units and use the ground plug in a country where it's required, if any do require grounding of the chassis over double insulated.

I assume my unit must be double insulated even though there is no indication on the back of the unit. I posted text below which indicates that Canada changed the CSA standards requiring a double-insulated marking effective Feb, 28, 2019, better late than ever ;-(