[Jay S]

Hi.  I'd really appreciate views/advice on how to ground a power filter/power strip.  

I understand the wall outlets in the U.S. & Canada are wired in parallel, while in the UK/Hong Kong a ring circuit is used (I live in Hong Kong).  I have also been told that a ring circuit grounds differently than the parallel circuit and, as a result, the ground of a power filter needs to be wired slightly differently to suit.  Can anyone explain this further?  What should be done differently and why?

I did a search on google and came across this diagram of a ring circuit.

http://www.bbc.co.uk/scotland/education/bitesize/physics/electricity/household_electricity_rev5.shtml

It seems that all outlets in a ring are in series.  My apartment has several circuit breakers (I per room), and also a residual current device (RCD) that I believe monitors leakage to ground and will trip if the leakage exceeds a certain level (50 mA?).  

Thanks!

- Jay

[ginger]

Hi.  I'd really appreciate views/advice on how to ground a power filter/power strip.  

I understand the wall outlets in the U.S. & Canada are wired in parallel, while in the UK/Hong Kong a ring circuit is used (I live in Hong Kong).  I have also been told that a ring circuit grounds differently than the parallel circuit and, as a result, the ground of a power filter needs to be wired slightly differently to suit.  Can anyone explain this further?  What should be done differently and why?

I did a search on google and came across this diagram of a ring circuit.

http://www.bbc.co.uk/scotland/education/bitesize/physics/electricity/household_electricity_rev5.shtml

It seems that all outlets in a ring are in series.  My apartment has several circuit breakers (I per room), and also a residual current device (RCD) that I believe monitors leakage to ground and will trip if the leakage exceeds a certain level (50 mA?).  

Thanks!

- Jay

Jay G'day from Oz (Australia)
Once you come out of the wall socket the grounding arrangement within the house wiring doesn't matter to you SO LONG AS YOU POWER YOUR ENTIRE AUDIO ARRANGEMENT from a single wall outlet. Just Wire the Mains filter ground to the wall socket ground pin and the Power Board/ Power Block (That thing with multiple power outlets) ground to the Filter Ground connection. In Oz at least you can buy a Power board with an integral Filter usually for Computer Equipment BUT will work fine for Audio Gear.

The situation you want to avoid with ring house wiring is having your Preamp, Power Amps, CD player etc. connected to multiple Wall Outlets since Earth Loops can then occur and you MAY get hum. For those items with just a 2 pin mains plug, ie "Double Insulated" equipment, you can get away with having them powered from a separate outlet since there is no earth connection.

Hope this is off help to you,

Cheers,
Ginger

[Jay S]

Jay G'day from Oz (Australia)
Once you come out of the wall socket the grounding arrangement within the house wiring doesn't matter to you SO LONG AS YOU POWER YOUR ENTIRE AUDIO ARRANGEMENT from a single wall outlet. Just Wire the Mains filter ground to the wall socket ground pin and the Power Board/ Power Block (That thing with multiple power outlets) ground to the Filter Ground connection. In Oz at least you can buy a Power board with an integral Filter usually for Computer Equipment BUT will work fine for Audio Gear.

The situation you want to avoid with ring house wiring is having your Preamp, Power Amps, CD player etc. connected to multiple Wall Outlets since Earth Loops can then occur and you MAY get hum. For those items with just a 2 pin mains plug, ie "Double Insulated" equipment, you can get away with having them powered from a separate outlet since there is no earth connection.

Hope this is off help to you,

Cheers,
Ginger

Hi Ginger,

Thanks for your message.  That is quite helpful.  Right now, my audio system is plugged into 2 separate single outlets.  1 outlet is for my digital source, the 2nd outlet is for everything else.  I notice that the RCD trips when I plug my filter into the 1st outlet, many times even before I can plug my digital source into the filter...  These 2 outlets are on the same circuit breaker.  I don't have this problem when I plug the power filter into an outlet in another room which is on a different circuit breaker.  

I seem to be able to plug my audio system into the 2 outlets on the same circuit breaker so long as I don't use the power filter.   The RCD doesn't trip.  And, I don't get hum.  Well, there's a little bit of hum but I only hear it when my ear is right next to the speaker and I figured it was because my preamp is tubed.

Looks like I would need a power filter that can supply my entire system without restricting dynamics -- this will allow me to plug the whole system into 1 single outlet.  My current filter won't work, therefore, since it limits current.

[ginger]

Jay,
The RCD tripping is of concern. This is suggesting that you have too much leakage current in your power filter - a fairly common problem with power filters. There is a trade off between the "agressiveness" of the filter and leakage current. The problem is in the 'Y' Capacitors - the ones from Active and Neutral back to Ground. These need to be well matched AND need to be special 'Y' Safety Rated Capacitors. Remember that RCD devices do NOT monitor Earth Current and Trip if it exceeds a certain limit, what they do is monitor the DIFFERENCE between Active and Neutral Currents and trip if this difference exceeds a threshold value. It is also possible (BUT less likely) that your RCD device has gone super sensitive and is tripping at lower current imbalances than it should. I've seen this happen at least twice in 5 years on the 6 RCD devices in the lab were I work.

Cheers,
Ginger

[Jay S]

Hi Ginger,

I have a friend who is an engineer and he calculated that the leakage from the filter is something like 10-15 mA (I can't remember offhand right now), vs the 30 mA rating of the RCD (at least that is the spec).  The designer of the filter indicated that I may need to half the value of the filter caps since I am using the filter in 230v rather than 115v.  I haven't done so yet as the leakage is below the specified trip point of the RCD.  

What is really wierd is that the filter works fine in outlets in other rooms in my home, and works fine in the homes of my friends.  It only trips the RCD when plugged into the outlet on the same circuit as the rest of my audio system.  Specificially, I plug the filter in the next outlet further from circuit breaker as the one where I plug in the rest of my system.  

I really do appreciate your comments as this problem with the filter has been driving me nuts for over the past year.   Many thanks!  

- Jay