7 Oct
2005
7 Oct
'05
7:26 a.m.
One for the US members... any idea of a good usenet resource for
questions relating to US wiring / electrics? (I'm thinking an equivalent
to uk.d-i-y)
We've got a cable decoder box here that trips out the house breakers
when plugged into certain outlets - irrespective of whether it's via a
surge protector (probably not surprising there) or of what other loads
might be sharing the same wiring to that outlet.
It works fine in other outlets though, which seems like a strange
problem - but I have no idea how US houses are wired (and the wiring in
this place is ancient anyway!)
Be nice to get it sorted out as the cable box currently requires a cable
trailing across the lounge from an outlet in another room!
cheers
Jules
7 Oct
7 Oct
7:42 a.m.
At 10:26 AM 10/7/2005, you wrote:
One for the US members... any idea of a good usenet
resource for
questions relating to US wiring / electrics? (I'm thinking an
equivalent to uk.d-i-y)
We've got a cable decoder box here that trips out the house breakers
when plugged into certain outlets - irrespective of whether it's via
a surge protector (probably not surprising there) or of what other
loads might be sharing the same wiring to that outlet.
It works fine in other outlets though, which seems like a strange
problem - but I have no idea how US houses are wired (and the wiring
in this place is ancient anyway!)
Be nice to get it sorted out as the cable box currently requires a
cable trailing across the lounge from an outlet in another room!
cheers
Jules
In a modern grounded system, green goes to the grounding
pin, white is common or neutral and goes to the longest of the
parallel slots, and black is hot, and goes to the short parallel slot.
Charles E. Fox Video Production
793 Argyle Rd. Windsor, Ontario
N8Y 3J8
Camcorder Kindergarten, www.chasfoxvideo.com
8:02 a.m.
All,
On 10/7/05, Charles E. Fox <cfox1 at cogeco.ca> wrote:
At 10:26 AM 10/7/2005, you wrote:
>One for the US members... any idea of a good usenet resource for
>questions relating to US wiring / electrics? (I'm thinking an
>equivalent to uk.d-i-y)
I am still trying to get my head around the UK wiring standards -
although optimising house wiring is, or very soon will be illegal in
the UK for all but licenced electricians.
In a modern grounded system, green goes to the
grounding
pin, white is common or neutral and goes to the longest of the
parallel slots, and black is hot, and goes to the short parallel slot.
What is the earthing arrangement?
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
8:36 a.m.
On 10/7/05, Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
We've got a cable decoder box here that trips out
the house breakers
when plugged into certain outlets - irrespective of whether it's via a
surge protector (probably not surprising there) or of what other loads
might be sharing the same wiring to that outlet.
It works fine in other outlets though, which seems like a strange
problem - but I have no idea how US houses are wired (and the wiring in
this place is ancient anyway!)
Check to see that you don't have neutral and hot swapped in certain
outlets. One painless way is an outlet tester sold at places like
Radio Shack and Lowe's. You can test with a voltmeter, if that's
easier, but the pre-fab tester lights up properly when plugged into a
properly-wired outlet, eliminating confusion.
In older houses, I've seen miswired outlets lots of times. My house
had two when I moved in , for example. Most appliances, especially
lighting fixtures, don't care. Best to identify and correct, anyway.
-ethan
9:13 a.m.
On 10/7/2005 at 11:36 AM Ethan Dicks wrote:
In older houses, I've seen miswired outlets lots of
times. My house
had two when I moved in , for example. Most appliances, especially
lighting fixtures, don't care. Best to identify and correct, anyway.
When I moved my home, I had a Toshiba microwave oven that refused to operate (would not
power up) when installed at the same outlet that had previously powered a Whirlpool unit.
Thinking it might be the outlet, I tried the oven on an extension cord plugged into a
different outlet--worked just fine. I plugged a worklight into the original outlet--no
problem. It dawned on my that there might be a fault in the outlet, but more of a
mechanical thing where contact wasn't being made with the Toshiba plug. After opening
up the outlet box, I noted that it had been installed with the wires (black/white) wires
swapped. On a hunch, I reversed them and reassembled the outlet. The Toshiba worked
fine.
I went around the house and discovered at least 8 more outlets with the same problem. The
house wasn't at all old and was wired by a licensed contractor and subsequently
inspected.
Regardless of how your outlet is (or isn't) labeled, it's the side of the outlet
that accepts the wider blade that is grounded, along with the long grounding prong. If I
were setting up a conversion from ungrounded 220v to US 120v, I woiuld make my receptacle
a GFCI model (ground fault circuit interrupter) model for safety...
---
If I remember what my friend from Aylesbury told me aobut UK wiring, it isn't uncommon
for a 50 amp 220 volt pair to be run to all outlets; the fuse being in the plug of the
appliance. He also mentioned that, although in theory, each appliance is to be fused
according to its current use, the common practice is to install a 13 amp fuse in
everything as a replacement.
On older hormes, it isn't uncommon to find that one side of the line has been grounded
through a buried cold-water pipe. However, as mentioned earlier, code requires a
separate buried grounding rod.
Cheers,
Chuck
9:50 a.m.
Chuck Guzis wrote:
If I remember what my friend from Aylesbury told me
aobut UK wiring, it
isn't uncommon for a 50 amp 220 volt pair to be run to all outlets;
Your friend would appear to live in a different UK to me. It is however
common practice for the outlets to be in a ring with a 30A fuse in the
fusebox.
the fuse being in the plug of the appliance. He also
mentioned that,
although in theory, each appliance is to be fused according to its
current use, the common practice is to install a 13 amp fuse in
everything as a replacement.
Most people don't understand the difference and it is more annoying to
get the correct fuse. It isn't helped by the manufacturers supplying
items with the wrong fuse. Those of us who perform Portable Appliance
Tests on things get very annoyed at having to replace the fuses on the
first test. Anyone want any 13A fuses? 8-)
Alistair
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
10:26 a.m.
On 10/7/2005 at 5:50 PM Alistair MacDonald wrote:
No my memory lives in a different reality from the current one! :) Still, it's not too
bad for recalling a casual conversaton I had some 12 or 13 years ago.
What is the common residential distribution in the UK? In the US, most residences seem to
be wired with 230v 200 amp service, although some of the newer houses in my neighborhood
are getting 400 amp panels.
The US 230 volt distribution takes the form of a center tapped secondary on the
distribution transformer, with the center tap being grounded. Distribution panels
alternate which side of the secondary is used, so a 230v circuit requires two breaker
positions, each breaker connecting with a different side of the distribution transformer
secondary winding.
Cheers,
Chuck
Your friend
would appear to live in a different UK to me. It is however
common practice for the
outlets to be in a ring with a 30A fuse in the
fusebox.
10:57 a.m.
On 10/7/05, Chuck Guzis <cclist at sydex.com> wrote:
What is the common residential distribution in the UK?
In the US, most residences seem to be wired with 230v 200 amp service, although some of
the newer houses in my neighborhood are getting 400 amp panels.
In my area (older part of Columbus, OH, with houses built between
about 1910 and 1935), we have lots of the old 60 Amp drops with 3
parallel light gauge wires, and lots of the modern 200 Amp
2-insulated-plus-one-uninsulated bundles. I haven't seen any 400 Amp
drops, but I suppose I wouldn't be able to distinguish them from 200
Amp drops by sight.
-ethan
11:30 a.m.
On Fri, 07 Oct 2005 19:57:14 +0200, Ethan Dicks <ethan.dicks at gmail.com>
wrote:
On 10/7/05, Chuck Guzis <cclist at sydex.com>
wrote:
200A @ 110V makes for 22kVA per phase - what do you need all that power
for?
I use electrical heating (in southern Norwegian climate), and rarely need
more than 7kW.
Looks like it will be cost effective again this winter, so I have not
filled the oil tank...
One special feature of Norwegian wiring is that we do not have any concept
of "neutral", since the distribution transformers are delta-connected.
Both phase wires are supposed to have the same potential to earth. This
makes the shock hazard from 230V not much higher than from 110V, since
most shocks are between a wire and earth. On the other hand, it does not
always work well with equipment built on the premise that there is a
neutral wire.
Anybody else living in a place that does not use Y-connected transformers?
--
-bv
What is the common residential distribution in
the UK? In the US, most
residences seem to be wired with 230v 200 amp service, although some of
the newer houses in my neighborhood are getting 400 amp panels.
In my area (older part of Columbus, OH, with houses built between
about 1910 and 1935), we have lots of the old 60 Amp drops with 3
parallel light gauge wires, and lots of the modern 200 Amp
2-insulated-plus-one-uninsulated bundles. I haven't seen any 400 Amp
drops, but I suppose I wouldn't be able to distinguish them from 200
Amp drops by sight.
2:18 p.m.
On 10/7/2005 at 8:30 PM Bj?rn wrote:
200A @ 110V makes for 22kVA per phase - what do you
need all that power
for?
Line voltage in the US is now closer to 120 v phase-to-ground; my own house measures about
124 v. most of the time So we're really talking about 24kVA per phase.
Why all the power? Well, first of all, I live in the Pacific Northwest, where most of the
power comes from hydro sources and prices are fairly low. I'm also situated outside
of city limits and served by a NRECA rural electrical co-operative, so there's some
government assistance with the infrastructure costs.
Cooking, heating and air-conditioning (via heat pump) is all electrical here. I refuse to
bring propane (from an outside tank) into my house because of safety concerns. During the
winter, our heating is supplemented with a wood-burning stove.
My home's hookup is somewhat different from the typical urban dweller's. An
above-ground 7200v 3-phase feeder line extends from the substation approximately 1/2 mile
away and one phase of this is taken underground at the corner of my property.
Approximately 400 feet later, a pedestal-mounted circuit breaker (I believe the co-op
calls them "reclosers") is located at the foot of my driveway. The 7200v cable
continues buried about 4' down along the remaining 200 feet of my driveway to a
pedestal-mounted transformer in my front yard. The 240v from the transformer then is
routed underground and enters my home slightly below grade level and is connected to a
conventional outside wall-mounted KWH meter.
Cheers,
Chuck
2:29 p.m.
200A @ 110V makes for 22kVA per phase - what do you
need all that
power for?
I didn't write that, but, I'd want excess capacity. :) I don't want my
main breaker to pop just because I have the stove, the baseboard
heaters, the laser printer, and the BA123 all on and happen to turn on
the hair dryer too. You have to use peak load, not average load, after
all, when working out power feed ampacity. :)
One special feature of Norwegian wiring is that we do
not have any
concept of "neutral", since the distribution transformers are
delta-connected.
...?? Are your two hot phases only 120? from one another, then, rather
than 180?? Surely not....
Both phase wires are supposed to have the same
potential to earth.
...which, at least in my (admittedly rather limited) experience with
Norwegian mains, can often differ substantially from the reality. :-/
I think the worst I saw was about 75V on one side and 135V on the
other. But this was in a borettslag that quite likely had not been
wired as well as it should have been and was probably not that close to
its substation besides (note that 75V+135V = 210V, which is a bit low).
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse at rodents.montreal.qc.ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
2:50 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
I was wondering since IBM produced OS/2 did any of their machines (PS/2
series maybe) run OS/2 better then clones or other companies machines. I
have OS/2 1.1 Extended up to 4.0 in my collection and was thinking of
getting a dedicated machine to test them out on. Since I have used Warp
before I was thinking about trying the older versions like 2.1.
Any ideas?
3:18 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
Teo Zenios wrote:
I was wondering since IBM produced OS/2 did any of
their machines (PS/2
series maybe) run OS/2 better then clones or other companies machines. I
have OS/2 1.1 Extended up to 4.0 in my collection and was thinking of
getting a dedicated machine to test them out on. Since I have used Warp
before I was thinking about trying the older versions like 2.1.
Any ideas?
I know that they used OS/2 as on the PS/2's that were microcode support
machines for
their S/390 machines, and probably still do. I believe that many of
those machines now
have thinkpad console support laptops as well.
A bit off topic, but as to compatability, the basic stuff in an PS/2 is
not very far from
the basics, and I am not aware of any problems with the basic boxes.
You will run into
problems getting drivers for OS/2 when you start adding tape drives,
external floppies,
scsi external, and so forth, as you will with any older box.
IBM shut down its PC support site some time ago, and I don't know where
you can
go for anything old anymore. I doubt that even the annoying pseudo porn
sites like
device-drivers.com or whatever would have much in the way of OS/2 support
though that site and it's clones are just repositories of pointers and
generators of
annoying ad pop ups (hence my tagging them as pseudo porn for the unkillable
popup behaviour)
jim
3:55 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
jim stephens wrote:
IBM shut down its PC support site some time ago, and I
don't know where
you can
go for anything old anymore. I doubt that even the annoying pseudo porn
sites like
device-drivers.com or whatever would have much in the way of OS/2 support
though that site and it's clones are just repositories of pointers and
generators of
annoying ad pop ups (hence my tagging them as pseudo porn for the
unkillable
popup behaviour)
Google MCA Mafia for microchannel support, and the Hobbes archives
are still around.
I have v4.0 running on a P-III with ATA-100, 10/100mb ethernet, and
an AGP ATI Rage Pro running at 1280x1024x24 with the SciTech Display
Doctor driver.
For OS/2 v3 and previous, as far as I can tell any drivers/hardware
support that existed then are still available, but that's still a pretty
narrow field.
Doc
3:38 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
On Fri, 7 Oct 2005, Teo Zenios wrote:
I was wondering since IBM produced OS/2 did any of
their machines (PS/2
series maybe) run OS/2 better then clones or other companies machines. I
NO.
Most of the PS/2 design was done with DOS 2.X and 3.X
MICROSOFT (Gordon Letwin) wrote OS/2 for generics.
IBM's marketing and subsequent mods were not PS/2 specific.
have OS/2 1.1 Extended up to 4.0 in my collection and
was thinking of
getting a dedicated machine to test them out on. Since I have used Warp
before I was thinking about trying the older versions like 2.1.
Any ideas?
--
Fred Cisin cisin at xenosoft.com
XenoSoft http://www.xenosoft.com
PO Box 1236 (510) 558-9366
Berkeley, CA 94701-1236
5:15 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
On Fri, 7 Oct 2005 17:50:25 -0400
"Teo Zenios" <teoz at neo.rr.com> wrote:
I was wondering since IBM produced OS/2 did any of
their machines
(PS/2 series maybe) run OS/2 better then clones or other companies
machines. I have OS/2 1.1 Extended up to 4.0 in my collection and was
thinking of getting a dedicated machine to test them out on. Since I
have used Warp before I was thinking about trying the older versions
like 2.1.
Any ideas?
A few years back I worked at a Medical Device manufacturer who developed
an embedded product using OS/2. So there was a whole team of OS/2
developers. This was actually one of the last large outside-IBM
embedded OS/2 shops, in fact. It was later (the OS/2 Warp era) but
there was not a single Microchannel machine in sight. Lots of IBM
machines from the post PS/2 era, though.
I have an IBM PC Server 704 (a big file cabinet sized quad pentium pro
behemoth) and there's OS/2 drvier support for it. My recommendation is
to tailor your hardware choice to systems that have good driver support
in OS/2.
I wouldn't mind running my PC Server 704 as an OS/2 Warp Server, but I
don't have any idea where to track down Warp Server installation media.
It's a dandy machine running NetBSD 2.0 at present.
8 Oct
8 Oct
6 a.m.
New subject: Best OS/2 1.3 or 2.1 Machine
On Sat, 08 Oct 2005 02:15:00 +0200, Scott Stevens <chenmel at earthlink.net>
wrote:
I wouldn't mind running my PC Server 704 as an OS/2 Warp Server, but I
don't have any idea where to track down Warp Server installation media.
It's a dandy machine running NetBSD 2.0 at present.
http://www.ecomstation.org/
eComStation is the SOHO distribution of OS/2, and after IBM stopped retail
sales it is the only retail outlet for OS/2. I have one IBM WSeB and two
eComStation systems, and they are basically identical except that eCS
keeps getting updated. One eCS is running as an intranet server with JBoss
among other things, but it is a rather modern system (AMD 2400+).
I think all pre-WSeB versions will run on a 386 processor, but one of the
fixpacks changed the requirement to 486 because it started to use new
instructions.
--
-bv
6:09 a.m.
New subject: Best OS/2 1.3 or 2.1 Machine
On Fri, 07 Oct 2005 23:50:25 +0200, Teo Zenios <teoz at neo.rr.com> wrote:
I was wondering since IBM produced OS/2 did any of
their machines (PS/2
series maybe) run OS/2 better then clones or other companies machines. I
have OS/2 1.1 Extended up to 4.0 in my collection and was thinking of
getting a dedicated machine to test them out on. Since I have used Warp
before I was thinking about trying the older versions like 2.1.
With OS/2 versions 1.x, there were at times dramatic performance
differences between a PS/2 and an AT or compatible, or more precicesly
between ABIOS/MCA computers and those without ABIOS. It was very
noticeable when you used the database server.
I spent a lot of time trying to get Microsoft OS/2 1.1 working properly on
an early Mitac 386. It took some faxes to the Mitac developers in Taiwan
(who were not too fluent in English) to get the problems solved.
With OS/2 version 2.x and newer, there is no difference that I have
noticed.
--
-bv
9 Oct
9 Oct
7:25 p.m.
New subject: Best OS/2 1.3 or 2.1 Machine
Teo Zenios wrote:
I was wondering since IBM produced OS/2 did any of
their machines (PS/2
series maybe) run OS/2 better then clones or other companies machines. I
have OS/2 1.1 Extended up to 4.0 in my collection and was thinking of
getting a dedicated machine to test them out on. Since I have used Warp
before I was thinking about trying the older versions like 2.1.
Any ideas?
PS/2 Model 80 or Model 95.
Or if you want something smaller, a Model 90.
Peace... Sridhar
7 Oct
7 Oct
4:32 p.m.
On 10/7/05, Bj?rn <bv at norbionics.com> wrote:
On Fri, 07 Oct 2005 19:57:14 +0200, Ethan Dicks
<ethan.dicks at gmail.com>
wrote:
> In my area...old 60 Amp drops... and lots of the modern 200 Amp
200A @ 110V makes for 22kVA per phase - what do you
need all that power
for?
I use electrical heating (in southern Norwegian climate), and rarely need
more than 7kW.
Electric heat, electric hot water, electric oven, electric clothes
dryer, air conditioner, 2-3 TVs...
It's typical to see a couple of 20A 220V breakers for things like
dryers, plus 30-50A for stove, plus I don't know what for heat (never
had electric heat) in a 200A panel, plus at least ten 20A breakers for
wall outlets and light fixtures.
I would suspect that some time ago (40 years? 50 years?) they looked
at the "standard" 60A feed designed in the days of electric lights and
little else, and decided that 200A was good enough to handle "most"
consumer needs without spending too much money on excess
infrastructure. I do not know what devices resulted in that number,
but I'm sure a 50A electric stove was part of it (there's one in the
other room - upper and lower ovens and 4 burners). Electric hot water
heat is also demanding (but I've never lived in an "all electric home"
- I've always lived in older, gas-plumbed areas).
If there's anyone on the list who is a US licensed electrician,
perhaps they could speak up if they learned about this facet of
history at some point during their career; I'm just speculating based
on what I've seen in my geographic area.
-ethan
4:36 p.m.
On Fri, October 7, 2005 5:50 pm, Alistair MacDonald said:
Your friend would appear to live in a different UK to
me. It is however
common practice for the outlets to be in a ring with a 30A fuse in the
fusebox.
Indeed, I've never seen a 50a pair run like that though obviously I've
never been to every house in the UK :)
items with the wrong fuse. Those of us who perform
Portable Appliance
Tests on things get very annoyed at having to replace the fuses on the
first test. Anyone want any 13A fuses? 8-)
Those of us who do electrical work (before getting the appropriate
government body in to test and sign off etc....jeez!) despair at portable
lights and kettles etc run off 13A fuses because 'that'll work won't it'
ObClassiccmp: I saw a PET 8032 with 8050 floppy drive and printer
yesterday. Bet all of it had 13A fuses :D
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
This message has been scanned by me and determined to be text based and
therefore not susceptible to virus attack. 'rah for text based emails!
Anyone heard of anything so ridiculous?!
(sorry :))
--
adrian/witchy
Binary Dinosaurs creator/curator
www.binarydinosaurs.co.uk - the UKs biggest home computer collection?
8 Oct
8 Oct
3:52 a.m.
Witchy wrote:
Blame Debian -- MailScanner just got upgraded and decided to add that
ridiculous message to every single message it checks. It was turned off
shortly afterward when I noticed it modifying incoming messages.
Alistair
ObClassiccmp: I saw a PET 8032 with 8050 floppy drive
and printer
yesterday. Bet all of it had 13A fuses :D
That reminds me -- must pick up those two PETS and floppy drives from
Leeds ... 8-)
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
This message has been scanned by me and determined to be text based and
therefore not susceptible to virus attack. 'rah for text based emails!
Anyone heard of anything so ridiculous?!
(sorry :))
7 Oct
7 Oct
1:11 p.m.
Ethan Dicks wrote:
On 10/7/05, Jules Richardson <julesrichardsonuk at
yahoo.co.uk> wrote:
Hmm, just had a quick look and no problems with the outlets which have
been causing problems - unless the whole lot's miswired where it exits
the breaker(s). I'll check that. And yep, it's all the old 60A
three-cable stuff.
The plot thickens somewhat after getting some more info out of the SO
and doing some poking around.
The problem only happens on certain outlets when the TV and cable box
share any of the problem outlets, and the aerial's hooked up between the
TV and cable box. (so I was incorrect about it *just* needing the cable
box plugged in to cause problems)
So it seems to be something to do with the TV and cable box having a
connection via the aerial lead that's causing trouble, but only when
they're using certain power outlets. The lead between power outlet and
cable box is a moulded thing and can only go one way round at either end
(the socket's PCB mounted at the cable box, so it can't be mis-wired
internally either). The TV has an integral lead, although I tried
swapping wires at the plug without any luck (it refuses to startup with
them swapped)
So it'd seem like some other issue - possibly a fault within the cable
decoder of some description, or maybe something else which is sharing
the cable feed (there's a cable modem on there too, and also another TV
without any decoder in one of the bedrooms)
Anyway, still looking for suggestions of places to ask all of this so
it's not on the list!
cheers
Jules
We've got a cable decoder box here that trips
out the house breakers
when plugged into certain outlets - irrespective of whether it's via a
surge protector (probably not surprising there) or of what other loads
might be sharing the same wiring to that outlet.
It works fine in other outlets though, which seems like a strange
problem - but I have no idea how US houses are wired (and the wiring in
this place is ancient anyway!)
Check to see that you don't have neutral and hot swapped in certain
outlets. 
9:44 a.m.
At 09:11 PM 10/7/05 +0100, you wrote:
Ethan Dicks wrote:
I once worked in a hospital and repairing the TVs was one of my
responsibilities. One day we had a call for a TV that won't work. When we
arrived it was working fine. A little latter we had a call for the same
thing from the adjacent room. This time we checked closer. We found that
the TVs were back to back on a common wall and both TVs used the same
electrical circuit. Somewhere there was an open circuit between the AC
outlets such that the two TVs were in series so neither one would work
unless both were turned on! That's why the patients TVs were dead, one
patient would turn their set off and it would turn both of them off. The
surprising thing was that both sets worked normal when in series. Very
surprising since each one was running off 1/2 the normal voltage!
It sounds like you might have something similar going on especially since
it seems to involve having the ariel and/or cable box hooked up.
Joe
On 10/7/05, Jules Richardson
<julesrichardsonuk at yahoo.co.uk> wrote:
Hmm, just had a quick look and no problems with the outlets which have
been causing problems - unless the whole lot's miswired where it exits
the breaker(s). I'll check that. And yep, it's all the old 60A
three-cable stuff.
The plot thickens somewhat after getting some more info out of the SO
and doing some poking around.
The problem only happens on certain outlets when the TV and cable box
share any of the problem outlets, and the aerial's hooked up between the
TV and cable box. (so I was incorrect about it *just* needing the cable
box plugged in to cause problems) We've got a cable decoder box here that trips
out the house breakers
when plugged into certain outlets - irrespective of whether it's via a
surge protector (probably not surprising there) or of what other loads
might be sharing the same wiring to that outlet.
It works fine in other outlets though, which seems like a strange
problem - but I have no idea how US houses are wired (and the wiring in
this place is ancient anyway!)
Check to see that you don't have neutral and hot swapped in certain
outlets.
So it seems to be something to do with the TV and cable box having a
connection via the aerial lead that's causing trouble, but only when
they're using certain power outlets. The lead between power outlet and
cable box is a moulded thing and can only go one way round at either end
(the socket's PCB mounted at the cable box, so it can't be mis-wired
internally either). The TV has an integral lead, although I tried
swapping wires at the plug without any luck (it refuses to startup with
them swapped)
So it'd seem like some other issue - possibly a fault within the cable
decoder of some description, or maybe something else which is sharing
the cable feed (there's a cable modem on there too, and also another TV
without any decoder in one of the bedrooms)
Anyway, still looking for suggestions of places to ask all of this so
it's not on the list!
cheers
Jules
1:05 p.m.
I once worked in a hospital and repairing the TVs
was one of my
responsibilities. One day we had a call for a TV that won't work. When we
arrived it was working fine. A little latter we had a call for the same
thing from the adjacent room. This time we checked closer. We found that
the TVs were back to back on a common wall and both TVs used the same
electrical circuit. Somewhere there was an open circuit between the AC
outlets such that the two TVs were in series so neither one would work
unless both were turned on! That's why the patients TVs were dead, one
patient would turn their set off and it would turn both of them off. The
surprising thing was that both sets worked normal when in series. Very
surprising since each one was running off 1/2 the normal voltage!
Were they, though?
Obviously, I don't know the details, but the most obvious way this could
happen on the US mains wiring system would be if one live ('hot') side of
each socket outlet was wired to each side of the centre-tapped mains. The
neutral sides of the sockets were linked together, but for some reason
that connection was not connected back to the centre-tap of the mains
supply. That would put the 2 TVs in series across the 230V mains.
Assuming they were similar sets, each would see about 115V.
-tony
5:33 p.m.
Jules Richardson wrote:
So it seems to be something to do with the TV and
cable box having a
connection via the aerial lead that's causing trouble, but only when
they're using certain power outlets.
Determine if there is a potential between the aerial lead and the TV or
cable box.
A story, perhaps helpful, perhaps not:
A couple of years ago, the lights in my house dimmed and brightened
noticably when the refrigerator would turn on or I would toast bread or
iron a shirt. I came to the conclusion that the neutral lead into my
house had excessive resistance. It was only a volt or two change when I
measured it, so I didn't think it was a problem.
Later, I was changing some cable TV wires and noticed that one was
actually warm to the touch. I went out to the telephone pole where the
wire came out the soil from my house and it was HOT. I fiddled with the
wire a bit and it melted and came apart, throwing sparks as it did.
The neutral conductor in the underground cable into my house failed at a
buried junction. For some time, my house neutral currents were carried
by the cable company's coax shield. It is interesting that none of the
other "ground" connections carried much current back to the transformer
on the pole. There were 5 paths to the pole: the neutral that failed, a
groundrod, the water main, the gas main, and the cable wire, and all the
current seems to have gone through the cable wire.
-chuck
11:59 a.m.
We've got a cable decoder box here that trips out
the house breakers
when plugged into certain outlets - irrespective of whether it's via
a surge protector (probably not surprising there) or of what other
loads might be sharing the same wiring to that outlet.
Two-prong plug or three? If two, polarized (blades different widths)
or not (identical blades)? Does it trip the breaker when it's plugged
in or when it's turned on (or does it not have a power switch)? Does
the breaker trip instantly, after a few seconds, after a minute or so,
or what? Does it do this even if it's not connected to anything else
(ie, with the cable, feed to the TV/VCR, etc disconnected)? If you can
reverse the plug (ie, if it's a non-polarized two-pin plug), does it
still trip if you do so?
I'm suspecting a power fault (a connection between a mains rail and
something else), with either (a) a non-polarized plug and tripping
depending on which way it happens to be plugged in rather than which
outlet or (b) a polarized or three-prong plug with the leak between
neutral and ground (ground via something like the cable sheath
conductor, or, of a three-pin plug, possibly via the ground pin) and
some outlets wired with neutral and hot swapped.
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