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[leonpc]

I have used x10 now since 1996 and have used the X10 XPCP or the Leviton version to bridge the phases without a problem on at least 4 occasions.  About a year ago I moved into a new house and pretty soon installed an X10 XPCP that I bought from an eBay reseller.  It worked for less than 5 minutes.  After I removed the XPCP, I opened it up to find a couple of blown capacitors in it. I assumed that the unit was faulty and decided to replace it with a Leviton counterpart.  To my amazement the Leviton unit also worked for only about 5 minutes.  I ordered another Leviton, called an electrician and explained what had happened.  Obviously I suspected an issue with my wiring (or rather the house's wiring).  The electrician checked things out, gave it a clean bill of health and installed the Leviton.  Unfortunately 5 minutes later I had another blown Leviton coupler/repeater.  It was getting very expensive, so I did not try it again.  I actually moved cable runs in the box so that I could have all my x10 units on the same phase.  Unfortunately I have now reached a point where that is no longer an option.  The electrician just shrugged his shoulders and said as far as he can see everything was fine.  Well obviously it is not.  Have I missed something?  What would blow these coupler/repeaters?  Where can I even start looking. 
I am considering one of the XTB units since I will have some cable runs  over 300 feet but before I install that I need to find out why the couplers blow up...

Thanks

Leon

[JeffVolp]

The XPCP has twin tuned-circuit coupling networks connected by a pair of capacitors.  I assume it is the pair of capacitors between the coupling networks that were destroyed.  They bridge the signal across the two phases, and see the full "rail-to-rail" voltage.

Capacitors can be damaged from over voltage.  Perhaps you have a voltage transient well in excess of the normal 340V peak voltage across the two phases.  It might be worth adding a whole-house surge protector to snub something like that.

I don't recall what voltage rating is used for the capacitors inside the XPCP, but the SmartHome 4816H coupler has a capacitor rated for 400VDC.  As you can see, there isn't much margin above the expected 340V peak.  Coupling capacitors in the XTB-IIR are rated 630VDC/250VAC.

(FYI - the X10 spell checker offered some interesting options on this post.)

Jeff

[dave w]

leonpc and Jeff
FWIW
Being the devils advocate here, and putting on my Nomex flame proof tights smeared liberally with anti caustic remark gel....

Are these XPCP being installed correctly? Are they the same date code?

Admittedly, I can not think of a way to install passive couplers and get them vaporise on a 220V panel. However the fact that they all have failed within 5 minutes of installation hints to me that the spikes Jeff is thinking of,  is on your system all the time, and I would think if that the case, they would have produced other failures in your home in the year you have lived in the home.

The date code inquiry is open minded consideration of X10 building them wrong or using mis labled or faulty parts and I am quite sure the ever capable X10 QA-QC checks would have caught that instantly. 

[JeffVolp]

Admittedly, I can not think of a way to install passive couplers and get them vaporise on a 220V panel. However the fact that they all have failed within 5 minutes of installation hints to me that the spikes Jeff is thinking of,  is on your system all the time, and I would think if that the case, they would have produced other failures in your home in the year you have lived in the home.

Actually, the XPCP could be damaged if it is not connected properly.  Unlike the simple SignaLinc 4816H, which is just a 2-wire device, the XPCP connects to hot and neutral on both phases.  Misconnecting it could put 240V across a 120V input.  I did not suggest that option because the connections were apparently verified by an electrician.  However, on reflection, it is certainly a possibility.

Regarding the transient, a low energy voltage spike would not cause a problem for most electrical devices, but could punch through the insulation of a capacitor.  We have a pretty good size transient here that falls right in the middle of the X10 transmission window.  I have never found the cause.

Jeff

[dave w]

Regarding the transient, a low energy voltage spike would not cause a problem for most electrical devices, but could punch through the insulation of a capacitor. 
Jeff

I was thinking of constant spikes (since everything blows up in 5 minutes after install, it must be all the time) with amplitude high enough to short the caps, would reek havoc on switching power supplies. However a neuron just fired...I wonder if each time the XPCP was replaced, the main breaker was used. If so,  that would explain why other gizmos in the house were not blowing up, since the main breaker use produced the damaging spike(?).

[Brian H]

Well if other devices where also failing a bad Neutral could unbalance the loads. That said the Electrician should have found such a problem.

[JeffVolp]

Reading through this thread again, I saw the part number XPCP listed several times, which is just a passive coupler.  That is the unit I described earlier.  Later in the original post there is reference to a coupler/repeater.  That is the XPCR.  If this is the XPCR (or its Leviton equivalent), that is an active device with a transformerless power supply.

Transformerless power supplies can be damaged by non-sinusoidal waveforms, as some have found out trying to run their X10 equipment from an UPS.  However, the failure is usually either a current limiting resistor or zener diode.  A fast rise time should not bother the capacitor.

What WOULD damage the capacitors in a transformerless power supply is a poor or open neutral connection.  Each phase normally receives 120V.  A bad neutral connection could result in almost double the normal voltage appearing across the power supply AC input capacitor.

Jeff

[Brian H]

I also thought it was the XPCP passive unit.

[leonpc]

Thanks Jeff, Dave and Brian for your insightful comments.

As it is, I replied with some additional comments based on the information you provided, but somehow it never posted to the forum. So I will try it again but it will probably be a  summary from my post last night.

JeffVolp said on: March 03, 2009, 06:09:06 AM

Perhaps you have a voltage transient well in excess of the normal 340V peak voltage across the two phases.  It might be worth adding a whole-house surge protector to snub something like that.

Since I work out of the house with some advance equipment, I had a whole house surge protector installed by the utility company within a week of moving in.  They installed it at the meter outside the house.  So far it seems to have done a good job.  I also use 4 ACT AF120 plugin filters along with power conditioning UPSs to isolate computers and audio equipment.  That may be why I have not noticed the issue with other equipment.

dave w said on: March 03, 2009, 11:11:15 AM

would reek havoc on switching power supplies. However a neuron just fired...I wonder if each time the XPCP was replaced, the main breaker was used

Yes the main breaker was used.  Would it help to switch the individual breakers off before turning the main breaker on?  Once the main breaker is on I can then turn on the individual breakers one at a time. 

JeffVolp said on: March 03, 2009, 02:13:48 PM

Reading through this thread again, I saw the part number XPCP listed several times, which is just a passive coupler.  That is the unit I described earlier.  Later in the original post there is reference to a coupler/repeater.  That is the XPCR.  If this is the XPCR (or its Leviton equivalent), that is an active device with a transformerless power supply.

I should have checked the equipment before I wrote the post.  As it is I first installed a X-10 XPCP.  I replaced it with a Leviton HCA02 and when the Leviton did not survive either I used a X-10 XPCR.  Even though the electrician could not see any problem, I wonder if there is a way to test the neutral connection?  If I move the installation to the other side of the distribution panel I would be using breakers in a different position in the distribution panel as well as a different neutral bar to connect to.  It should not really make a difference.

Again thanks in advance.
Leon

[JeffVolp]

Since the failure was the XCPR or Leviton equivalent repeater, I have to go with a bad neutral being the cause.  MOVs and fuses were popped in a couple of XTB-II/R units due to a bad neutral connection.

Depending on how the load balances, an open neutral can place most of the 240V across an input designed for 120V.  That obviously can cause devices to fail.

I believe both the XCPR and Leviton equivalent use a white wire for neutral.  Just make sure there is a solid connection from that to the neutral busbar in the panel.  If you slipped that into the same lug that is used for another wire, it is entirely possible that the smaller conductor did not make a connection.

Jeff