Axiom Home Page Forums General Discussion Home Theater Grounding question...

I can't believe I've owned my Denon for all of these years without noticing this, but I have. While redirecting some of the wiring in my HT closet yesterday I unplugged the Denon and noticed there were only 2 prongs sticking out from back of the denon to the power cord.... "CRAP"!!! I thought to myself, as I thought I'd somehow broken off the grounding prong. But after carefull inspection I realized that not only was nothing broken off inside the plug-in, there was never anything there to break off... there is no grounding prong. And yet there is a grounding prong that goes into the wall. This made me curious, are AVR's not grounded? I inspected the Emotiva and found the exact same thing, no grounding prong coming out of the back of the amp into the cord, but the other end of the cord is 3 prongs.

So do they wire the ground into either the positive or negative, or both in the wire itself? How do they ground them, if they are grounded at all. And if they aren't grounded, why not? I have seen a grounding prong coming out of the back of some appliance somewhere, I know I have, that's why I thought I'd broken it off when I didn't see it.

No grounding prong is quite common, my PB 13 and my 3808 do not have a grounding prong either. I have no idea why this is somewhat prevalent, never really thought about it. I do know it cuts down on ground loop humming to an extent.

I wonder if the 3808 had a grounding prong if my 'accident' with the A1400 would have been as bad, as I recently picked it up from the repair shop(after 4 months . It had been sent to Denon and the ground on the circuit board had been melted off the board!! They simply used a piece of wire to fix this issue, but if there was a true ground to the outlet would it have shunted the power better and saved the receiver?

As common as it may be, my question is.... why??? Why put a 3 prong cord on an appliance that isn't grounded? Andd if they in deed aren't grounded, then why do so many people warn against 'cheater plugs'? It seems to me if it isn't grounded in the first place then the cheater plug is of no significance what so ever.

They don't put 3 prong cords on appliances that are not grounded. They put 2 prong cords.

So they are grounded then? How do they ground them if not with a grounding post from the device to the cord?

If they are not grounded, they will have 2 prong. If they have 3 prong, they are grounded.

Fred, I think the confusion is stemming from his observation that there are three prongs on the male outlet side of his Denon supplied, detachable power cord and also three holes on the female end of his power cord
but
the receiver itself was built with only two male prongs to plug the cord into. The ground pin is not present on the receiver to plug a grounded cord into.

I can see why he would ask the question.

Now that makes sense. Thanks for the information reset.

I can't explain why a receiver is designed around a two-wire or three-wire system, but the cord is likely that way due to the economies of scale. I have five cords like that sitting in my closet they're so common!

Precisely! Thank you Murph for explaining it better than I could. So the question remains then, is the Denon not grounded? Even given the explanation that Mark theorized about economies of scale being the driving force behind using a three prong plug on an appliance that only had a two prong male connection... I am still miffed at why these recievers and amps aren't grounded? The Denon and Emotiva use the exact same cord as the EP800's amp does, only the Axiom has a three prong male connection where the other two don't. That is confusing to me. Why would one amp need grounding where the other two, by design, do not?

Strictly on the cord choice, Mark may be right and add to that the possible combined illusion of aesthetics.

Grounded, three prong cords are generally thick, heavy and round thus they appear to be much more like the professional, heavy gauge power cord that you would 'expect' to see feeding a powerful amp. The smaller, flat look of most two prong cords just don't give you the same comfort feeling, even if the wire is the same gauge inside.