Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I did consider venting to the outside wall, but it's upstairs
and the wall is rendered, and I'd rather not disturb the
render unless absolutely necessary. I have a number of
other options:

(i) Vent to and from the room
I could just put in grills with quiet fans on the face of the
cupboard somewhere - one to suck air in and one to push
it out. My worries are that:
(a) it will look bad
(b) it will sound worse than before
(c) it'll just push warm air around the case

(ii) Vent into the chimney breast
The cupboard will be next to the chimney breast, so I could
potentially put an extractor to take the hot air out into the
chimney. Both fireplaces are closed off but the chimney is
ventilated by grilles on the chimney breast. The air could
just be sucked into the cupbard through gaps round the door
or I could fit a grille.

(iii) Vent into the loft
The same as above but vent into the loft space. I could
conceivably end up venting to the outside via the eaves.

(iv) Vent to/from the loft/chimney breast
It occured to me that I could suck cold air in from the loft,
and vent the hot air out to the chimney breast, or vice versa.

What do people think?

Al Reynolds

Al Reynolds wrote:
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I did consider venting to the outside wall, but it's upstairs
and the wall is rendered, and I'd rather not disturb the
render unless absolutely necessary. I have a number of
other options:

(i) Vent to and from the room
I could just put in grills with quiet fans on the face of the
cupboard somewhere - one to suck air in and one to push
it out. My worries are that:
(a) it will look bad
(b) it will sound worse than before
(c) it'll just push warm air around the case

snip
What do people think?

I'll just mention what I did.
I started off with a PC in a knee-hole desks cupboard.
This was then lined with carpet, and two foam-mounted fans placed on
the back.

This was a good deal quieter.

Then I made an interior cupboard spaced some 1" in, also carpet-lined.
The fans were replaced with ones inside the inner cupboard that
connected to the outside of the inner cupboard (blowing in and sucking
out) through tunnels of carpet, and ducting (again of carpet) to the
original vent holes (which were in different places.

Alternatively, have you considered simply putting the PC in the attic?

In message , Al Reynolds
writes
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.


First off - what temps is the PC running now? You're probably pretty
safe with a CPU temp up to 50 degrees c, so stick it in the cupboard for
a bit and see how it goes. Not ideal but might save you some work. I
know people who have multiple servers/switches/routers inside an airing
cupboard and don't have any problems with overheating....

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

mike. buckley wrote:
In message , Al Reynolds
writes
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!
snip
First off - what temps is the PC running now? You're probably pretty
safe with a CPU temp up to 50 degrees c, so stick it in the cupboard for
a bit and see how it goes. Not ideal but might save you some work. I
know people who have multiple servers/switches/routers inside an airing
cupboard and don't have any problems with overheating....

Don't forget that you're not interested in what temperature it's at
now, but the temperature when it gets to 30C or so inside. (or
whatever the max temp is.)
Hard drives get lots less reliable as the temps climb.

Many hard drives have thermometers inside to measure the temp, and
can report via SMART.
Look for disk status monitoring tools.

You say it is a very small form factor, but exactly what? :-)

o Micro-ATX - CPU can be P3-Cel (30W) to P4-Prescott (115W)
o Mini-ITX - CPU can be VIA-C3 (12W) to P4-Prescott (115W)

You say it piles out a lot of hot air, which makes me think VIA C3.

Duct/Extractor to Outside = Static-Resistance + Continuous-Rating + Noise-Level
o PC-style 12V Axial fan - eg, 120x38, 171x51mm
---- +ve -- Continuous-Rated + Quietish + Cheap
---- -ve -- Low Pressure even from 38-51mm depth fans = Low Airflow
------- you can get away with a 172x51mm eg, Papst 6212NM, but it's not quiet
------- so you are then into noise-proofing the cupboard &/or fan
o Extractor Axial fan - eg, shower, toilet etc
---- +ve -- Easy Build-In off the shelf fitment + Acoustic enclosures for loft use
---- -ve -- NOT always Continuously-Rated (some Vent-Axia are) + Not quiet + Cost

Since this is just a single PC, I don't think this solution is worth the hassle.
With 16x 1U dual-processor PCs doing CFD it is a different matter re 4kW of heat.

Noise Reduction:
o Distance -- dB(A) drops off rapidly with distance
---- use K-V-M cable extensions to relocate the SFF-PC further away
---- the catch-22 is your removeable media - altho external USB enclosures exist
o Noise Source -- fans are one source (quiet fans exist), HDs another source
---- targetting the noise source is more effective than treating the effect
o Noise Effect -- an enclosure (cupboard) can be useful for reducing noise
---- soundproofing must use Mass (low frequency) & Absorption (high frequency)
-------- TreadAir Carpet Underlay - rubber (Mass) rippled foam (Closed-Cell)
-------- carpet may include nylon - running the risk of static
---- do not fit ventillation fans to the cupboard (re PC / soundproofing / fan / ear)
-------- soundproofing should between the source & your ear :-)
---- every 90-degree turn reduces noise by 3dB(A)
-------- like distance, acoustic baffles work well - especially if lined

Cupboard cooling:
o Natural convection
---- wood-slatted-door (prettier than vents)
---- at the rear of the slats, close of all except for the top & bottom
o Forced cooling
---- PC Axial fans will be ok here
---- Do not fit to cupboard front (line intake path to absorb fan noise)
---- Do not fit in narrow-end of an enclosure (acoustically this is ugly)

Baseline before/after the design:
o Identify Thermal Baseline Before -- CPU & Board Temp + HD Temp
---- onboard monitoring tools (MBM) + S.M.A.R.T. HD temp checker (HDDTemp)
o Identify Thermal Baseline After -- objective is HD 50oC, CPU 55oC
---- some degree of thermal stressing re s/w - since ambient is 30oC summer

Airflow required:
o EBM-Papst figure is 300cfm cools 1500W before adjustment for resistance
---- a crude heuristic rule of thumb ignoring ambient & mass of air, etc etc
o Adjustment will come down to solution choice
---- lo adjustment for cupboard - room (120x38mm fan will lose 25% of free-air
airflow)
---- hi adjustment for house - outside (120x38mm fan will lose 80% of airflow)

SFF enclosu
o You are re-housing the machine in a cupboard for noise
---- primarily I suspect this is due to fan noise, secondarily due to HD noise
o So why not re-house the machine itself in a different enclosure
---- one using say 80mm fans or a 120mm fan - in place of 60mm fans
-------- an issue would be a high-end graphics card fan - passive solutions exist
---- an enclosure such as a flight-case - £30-50 on Ebay
-------- off the shelf gives you dense plywood, nice finish, castors, door labyrinth
seal
-------- www.penn-fabrication.com do all the parts if you need more
-------- easy to add perforated-dish vents & inset the fans, line with carpet underlay

The easiest is tackling the source & using distance.
The messiest is an enclosure with duct through a wall - soundproofing the duct, the
enclosure, the intake, and achieving a quiet fan which is continuously rated. As you
move into larger fans they move from electronic cutout to thermal cutout - that means
if they fail (locked-rotor) or jam they will get extremely hot indeed re fire risk. That
fire
risk exists for cheap shower extractor fans which are not continuously rated, even more
so if you enclose them in the loft acoustic boxes - typical is 15min on, 30min off IIRC.

I would use distance + recycle an Ebay flight case + carpet underlay.
If a VIA C3, a small bottom intake vent & top exhaust vent in a cupboard will do fine
(convection).

Keep It Simple :-)
--
Dorothy Bradbury

"Al Reynolds" wrote in message
...
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I did consider venting to the outside wall, but it's upstairs
and the wall is rendered, and I'd rather not disturb the
render unless absolutely necessary. I have a number of
other options:

(i) Vent to and from the room
I could just put in grills with quiet fans on the face of the
cupboard somewhere - one to suck air in and one to push
it out. My worries are that:
(a) it will look bad
(b) it will sound worse than before
(c) it'll just push warm air around the case

(ii) Vent into the chimney breast
The cupboard will be next to the chimney breast, so I could
potentially put an extractor to take the hot air out into the
chimney. Both fireplaces are closed off but the chimney is
ventilated by grilles on the chimney breast. The air could
just be sucked into the cupbard through gaps round the door
or I could fit a grille.

(iii) Vent into the loft
The same as above but vent into the loft space. I could
conceivably end up venting to the outside via the eaves.

(iv) Vent to/from the loft/chimney breast
It occured to me that I could suck cold air in from the loft,
and vent the hot air out to the chimney breast, or vice versa.

What do people think?

Al Reynolds




Al,

I have a small form factor PC (Compaq EN SFF) running 24/7 doing various
control functions around the house. It sits in a normal 'wall cupboard' of
the tatty melamine variety, and I have installed 9"x3" air vents in the
bottom and top of the door. This had proved adequate for several years.
Quite a bit of sound deadening was achieved by placing it on a carpet
offcut.

Andrew Mawson,
Bromley,
Kent,
UK

"Al Reynolds" wrote in message
...
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I did consider venting to the outside wall, but it's upstairs
and the wall is rendered, and I'd rather not disturb the
render unless absolutely necessary. I have a number of
other options:

(i) Vent to and from the room
I could just put in grills with quiet fans on the face of the
cupboard somewhere - one to suck air in and one to push
it out. My worries are that:
(a) it will look bad
(b) it will sound worse than before
(c) it'll just push warm air around the case

(ii) Vent into the chimney breast
The cupboard will be next to the chimney breast, so I could
potentially put an extractor to take the hot air out into the
chimney. Both fireplaces are closed off but the chimney is
ventilated by grilles on the chimney breast. The air could
just be sucked into the cupbard through gaps round the door
or I could fit a grille.

(iii) Vent into the loft
The same as above but vent into the loft space. I could
conceivably end up venting to the outside via the eaves.

(iv) Vent to/from the loft/chimney breast
It occured to me that I could suck cold air in from the loft,
and vent the hot air out to the chimney breast, or vice versa.

What do people think?

Al Reynolds


For 1 PC I'd line the cupboard with underlay rather than carpet (less risk
of dust, fine fibres, static, etc), then egg trays. Then a couple of baffled
air vents. Should do the trick with no additional fans.

Cheers
Clive

On Mon, 27 Sep 2004 11:28:19 +0100, mike. buckley wrote:

First off - what temps is the PC running now? You're probably pretty
safe with a CPU temp up to 50 degrees c,

This 1GHz Athlon is normally at just below 60C. Wanders of to check,
hum, must need a good dusting again it's up at 70C... This machine
runs 24/7 with no trouble.

As to the OPs query, suitable quiet fans are normally fairly easy to
find. Just look at CPC, RS, Farnell, Rapid etc. Might be worth paying
the few quid extra for the temperature sensitive ones. Even knocking 5
or 10% of a fans speed will make a great difference to the noise
level.

One PC in a what sounds like a fairly large cupboard, I think I'd try
to make sure that it drew it's air from the relative cool of the room
and just vented into the cupboard. Why dump this (expensive as it's
sourced from electricity) heat outside? It'll help keep your house
warm.

--
Cheers
Dave. pam is missing e-mail

On Mon, 27 Sep 2004 10:22:20 +0100, "Al Reynolds"
wrote:

Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I did consider venting to the outside wall, but it's upstairs
and the wall is rendered, and I'd rather not disturb the
render unless absolutely necessary. I have a number of
other options:

(i) Vent to and from the room
I could just put in grills with quiet fans on the face of the
cupboard somewhere - one to suck air in and one to push
it out. My worries are that:
(a) it will look bad
(b) it will sound worse than before
(c) it'll just push warm air around the case

(ii) Vent into the chimney breast
The cupboard will be next to the chimney breast, so I could
potentially put an extractor to take the hot air out into the
chimney. Both fireplaces are closed off but the chimney is
ventilated by grilles on the chimney breast. The air could
just be sucked into the cupbard through gaps round the door
or I could fit a grille.

(iii) Vent into the loft
The same as above but vent into the loft space. I could
conceivably end up venting to the outside via the eaves.

(iv) Vent to/from the loft/chimney breast
It occured to me that I could suck cold air in from the loft,
and vent the hot air out to the chimney breast, or vice versa.

What do people think?

Al Reynolds


Hi,

Another option could be to fit a quiet CPU fan and have quiet
external ATX power supply in the cupboard. The cube would then be fed
from an extended ATX power lead.

cheers,
Pete.

"mike. buckley" wrote in message . uk...
In message , Al Reynolds
writes
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans.

First off - what temps is the PC running now? You're probably pretty
safe with a CPU temp up to 50 degrees c, so stick it in the cupboard for
a bit and see how it goes. Not ideal but might save you some work. I
know people who have multiple servers/switches/routers inside an airing
cupboard and don't have any problems with overheating....

A 2 GHz Pentium probably uses 100w power absolute max excluding
monitor. Put a 100 w lamp in the cupboard for a day and check the
temp rise. If its less than 10 deg C there is unlikely to be a
problem in the UK as the ambient temp never gets too high.

john

Keep the ATX extension lead to ~30cm re remote sensing (but not on all pins),
you can go a bit longer if the original PSU lead is a short one - but not infinite.

Frankly keep the solution simple:
o Baseline where you are now
o Change 1 variable at a time
o Do not thro money at the solution :-)
o Then establish how the new system compares & adjust accordingly

Treating cause is more effective that effect, although you will find
that treadair rubber underlay (and it's clones) is very effective. The
acoustic sound-barrier-mat, 5kg/m^2 & acoustic foam cost far more.

Typical coloco facilities run CPUs far hotter than most people realise,
but that does not mean you can neglect HD temps - S.M.A.R.T. utils.
--
Dorothy Bradbury
www.stores.ebay.co.uk/panaflofan for quiet Panaflo fans & other items
www.dorothybradbury.co.uk (free delivery)

In message , Al Reynolds
writes
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

These people are a good port of call for all manner of cooling and noise
suppression.

http://www.quietpc.com/uk/

Hth
Bill

In message om, Dave
Liquorice writes
On Mon, 27 Sep 2004 11:28:19 +0100, mike. buckley wrote:

First off - what temps is the PC running now? You're probably pretty
safe with a CPU temp up to 50 degrees c,

This 1GHz Athlon is normally at just below 60C. Wanders of to check,
hum, must need a good dusting again it's up at 70C... This machine
runs 24/7 with no trouble.


Blimey, that's running hot. I've also got an Athlon (2800, actually
2ghz) and it's below 50C, this is without any extra cooling apart from a
more expensive (thus quieter and cooler) PSU. If memory serves my mates
CPU cooler died (also a 2800) and the PC was ok til about 85C then it
hung.

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

Thanks for all the detailed advice people.

For info, it's an MSI Mega PC version 1. The
processor is 2.8 Ghz. Part of the problem is
that I'm using an nVidia FX5600 Ultra graphics
card which also has a fan on it. I don't really
want to replace the card. The other thing is that
I use a remote with the PC and the IR sensor is
on the front of the case, so I'm looking at a glass
door on the cupboard.

The discussion reminded me how loud my PS2
was before I put it in a glass-door-fronted cabinet
with the video and DVD. Now I can hardly hear
it with the door shut. I think I'll build the cupboard
with the option to add extra forced ventilation later,
and see how things go. I have a roll of unused
underlay in the loft, so that'll go in there as well.

Thanks again,
Al

"Al Reynolds" wrote in message ...
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans.
Anyway, it piles out a lot of hot air, and currently has
ventilation on both sides of the case. I'm conscious that
if I put it in a cupboard it may overheat quite quickly, so
I'm looking for options to ventilate the cupboard.

I'm trying to do something similar at the moment. I've a 3.0 P4 in a
Shuttle XPC case in my kitchen that i want to keep in one of the base
units. My day 1 test involved running the PC at about 70% for half
hour or so (ripping MP3's, decoding digital TV and playing mp3s). The
temperatures shot up very quickly from around 50C to 65C but what
concerned me was that they didnt drop afterwards - a couple of hours
close to idle but circulating the same air and it wasnt cooling down
significantly. My guess is that you WILL need to ventilate the
cuboard. I've not worked out how to solve my own problems yet but
will watch this thread.

Re the glass front/IR issue - An IR repeater might be neater than a
glass front. Check Keene electronics.

"anthony james" wrote:
Re the glass front/IR issue - An IR repeater might be neater than a
glass front. Check Keene electronics.

Good idea!
Al

On Mon, 27 Sep 2004 18:58:49 GMT, "Dorothy Bradbury"
wrote:

Keep the ATX extension lead to ~30cm re remote sensing (but not on all pins),

Really, how does that work? Are some of the duplicated ATX connections
used for this or are they commoned together?

cheers,
Pete.

Keep the ATX extension lead to ~30cm re remote sensing (but not on all pins)

Really, how does that work? Are some of the duplicated ATX connections
used for this or are they commoned together?

Typical desktop PC:
o Remote sensing is on the 3.3V rail
---- since 3.3V is quite a low voltage + power cables have length & voltage drop
---- and spec is +/- 5% which isn't a lot in voltage terms
o Implementation for desktop PCs is via pin 11
---- the power pins are commoned off the PSU PCB to distribute load per cable/pin
---- a few (Tyan dual CPU?) boards used to melt their ATX skts under high load
o Remote sensing is also required at the SATA 3.3V connector too IIRC
---- even the 2.5" SCSI 10k-rpm Savio is still 5V (I think)

Industrial PCs:
o Remote sensing can be on all of 3.3V, 5V & 12V rails
---- these still average across the ATX connector
o Remote sensing can get more sophisticated on mini-PCI multi-U arrays
---- these combine outputs from many std ATX PSUs re o/all current draw
---- they manage redundancy without expensive/unobtainable redundant PSUs

www.formfactors.org will have details for both ATX 2.1/2.2 & BTX.

Basically the spec just requires 3.3V remote-sensing.
I've never seen a cable length limit - but have seen 1.5m 1U PSU cables (oddly!).
If you take a standard ATX PSU, which has quite a long lead, some E-ATX super
server cases required a 30cm extension to be added to reach the power socket.

Never tried an 'overly-long' cable so can't comment on what happens, I suspect
the voltages would need careful monitoring during burn-in load testing. Would help
if the leads (wire) were a decent thickness - some are, and some are a bit skimpy.
--
Dorothy Bradbury
In RCD Nuisance Trip Hell.

On Wed, 29 Sep 2004 00:29:05 GMT, "Dorothy Bradbury"
wrote:

Typical desktop PC:
o Remote sensing is on the 3.3V rail
---- since 3.3V is quite a low voltage + power cables have length & voltage drop
---- and spec is +/- 5% which isn't a lot in voltage terms
o Implementation for desktop PCs is via pin 11
---- the power pins are commoned off the PSU PCB to distribute load per cable/pin
---- a few (Tyan dual CPU?) boards used to melt their ATX skts under high load
o Remote sensing is also required at the SATA 3.3V connector too IIRC
---- even the 2.5" SCSI 10k-rpm Savio is still 5V (I think)

Industrial PCs:
o Remote sensing can be on all of 3.3V, 5V & 12V rails
---- these still average across the ATX connector
o Remote sensing can get more sophisticated on mini-PCI multi-U arrays
---- these combine outputs from many std ATX PSUs re o/all current draw
---- they manage redundancy without expensive/unobtainable redundant PSUs

www.formfactors.org will have details for both ATX 2.1/2.2 & BTX.

Basically the spec just requires 3.3V remote-sensing.
I've never seen a cable length limit - but have seen 1.5m 1U PSU cables (oddly!).
If you take a standard ATX PSU, which has quite a long lead, some E-ATX super
server cases required a 30cm extension to be added to reach the power socket.

Never tried an 'overly-long' cable so can't comment on what happens, I suspect
the voltages would need careful monitoring during burn-in load testing. Would help
if the leads (wire) were a decent thickness - some are, and some are a bit skimpy.

I see. If i was to extend an ATX power cable I'd use some chunky
speaker cable for the high power connections, looks nice and a few
mm2+ is easily available. The lower power and signal connections would
be handled with standard 4 way flat speaker cable.

All the plugs would be moved down to the far end, using some
heatshrink which would look neat. Might need multiple cores or very
thick cable for the high power connections, I wonder what sort of
cable a standard ATX supply uses...

--
Dorothy Bradbury
In RCD Nuisance Trip Hell.

May be worth measuring leakage currents to see if they are excessive
when combined. Also test the wiring or equipment with a Megger or
something similar.

If it's intermittent earth leakage, connecting different equipment or
circuits into an isolation transformer or maybe even a UPS would help
narrow down the cause.

Failing heater elements, damp and even spideys can be a cause of
tripped RCDs.

cheers,
Pete.

I see. If i was to extend an ATX power cable I'd use some chunky
speaker cable for the high power connections, looks nice and a few
mm2+ is easily available. The lower power and signal connections would
be handled with standard 4 way flat speaker cable.
All the plugs would be moved down to the far end, using some
heatshrink which would look neat. Might need multiple cores or very
thick cable for the high power connections, I wonder what sort of
cable a standard ATX supply uses...

Do this to an ATX extension cable - rather than your PSU cable:
o Ebay probably has a few - either 9" or 12"/30cm
o Various online sellers do too - www.kustompcs.co.uk do them

Someone on Ebay sells any-length of any-colour of any-rating cable.
You may want to try a terminal block on the near-PSU connection,
just until you know what cable length doesn't affect PC stability.

Double heatshrink the joints & watch length of solder run into the
stranded cable core re mechanical inflexibility at that point.

In RCD Nuisance Trip Hell.

May be worth measuring leakage currents to see if they are excessive
when combined. Also test the wiring or equipment with a Megger or
something similar.

Split-load CU using 2 RCDs, 2 butyl rubber cables on the tripping-RCD
o 1ft long - radial to living-room skt other side of the CU
o 15ft long - radial to landing skt, subject to vacuum cleaner attack :-)

We suspect the latter, landing skt - also linked to a new PVC-T&E ring :-)
o I know the MCB has 3 wires - 1 butyl & 2x PVC-T&E
o I suspect the skt has 2 butyl (1 run to disused skt) & 1 PVC-T&E

I guess they linked the radial to the ring for redundancy & that 1 disused skt.

The electrician friend did a few checks:
o Opened the landing skt -- no RCD trips since
o Powering each MCB in turn -- the 1ft living-room butyl MCB tripped the RCD

Sounds like cumulative leakage on 2 cables, due to insulation creep
o Both are the original radial run, in butyl, to 1 socket only, in 4mm^2
o Fat cable so there's not a lot of space even in a double surface pattress

If it's intermittent earth leakage, connecting different equipment or
circuits into an isolation transformer or maybe even a UPS would help
narrow down the cause.

If it trips again, I'm going to repeat the tests again:
o RCD instantly reset = turn off all MCBs, turn on 1 by 1 & note if RCD trips
o RCD will not reset = turn off all MCBs, turn on 1 by 1 & note which trips RCD
o RCD & MCB trips = hurrah, at least it shows which circuit

It could conversely be insulation pressure in the CU itself on the butyl.

Failing heater elements, damp and even spideys can be a cause of
tripped RCDs.

Immersion is on the same RCD circuit (3 circuits), 10yr+ old element.
A lot to be said for RCBOs even tho just 3 circuits on that RCD.

Frankly I think the future will be:
o Verify it's a 2-PVC-Ring linked by 1-Butyl radial
---- then disconnect that radial at both ends
---- and use the 2-PVC-ring thro that landing skt
o Replace that 1ft butyl radial to living room skt
---- combined that removes 2 of the 3 butyl rubber cables

The living room skt 1ft should be a 3-min change, but everyone runs:
o CU is other side of the wall, displaced 12" horizontally
o Cable runs 12" thro a 1-brick-wall into alcove before the fireplace
o 3-5" into the alcove it goes thro the wall (behind quarry tile I guess) to skt
o Above the skirting-board skt is a skirting-board chromed gas pipe to the fire

Measured the skt to living room door & same the other side re position,
then measured the alcove depth v total fireplace depth - 10" = double-brick.

Electricians mumble "it's not straight thro", or "there's a chimney cavity",
but the floor is solid, and there's no bermuda triangle here. Then again I'm
not so sure IEE 16th onsite would like a new cable behind quarry tile skirting,
tho some 25x25mm galvanised may change that (over head or on skirting :-)

Since we don't know which, it's wait for the RCD to trip again & discriminate.
Historically, it hasn't and that is why the cables never got done.

Nuisance trips, then someone looks at it, then it never comes back.
I think Butyl suffers insulation creep? All springy but "ductile" stuff. Rubber :-)
--
Dorothy Bradbury

In article , "Al Reynolds" ajr-
says...
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

snip

What do people think?

Remove the existing fans and fit larger quieter ones on the outside of
the case (with suitable ducting)? Make a baffled box and line it with
sound-absorbing material?

On Wed, 29 Sep 2004 22:43:54 GMT, "Dorothy Bradbury"
wrote:

Frankly I think the future will be:
o Verify it's a 2-PVC-Ring linked by 1-Butyl radial
---- then disconnect that radial at both ends
---- and use the 2-PVC-ring thro that landing skt
o Replace that 1ft butyl radial to living room skt
---- combined that removes 2 of the 3 butyl rubber cables

The living room skt 1ft should be a 3-min change, but everyone runs:
o CU is other side of the wall, displaced 12" horizontally
o Cable runs 12" thro a 1-brick-wall into alcove before the fireplace
o 3-5" into the alcove it goes thro the wall (behind quarry tile I guess) to skt
o Above the skirting-board skt is a skirting-board chromed gas pipe to the fire

Measured the skt to living room door & same the other side re position,
then measured the alcove depth v total fireplace depth - 10" = double-brick.

Electricians mumble "it's not straight thro", or "there's a chimney cavity",
but the floor is solid, and there's no bermuda triangle here. Then again I'm
not so sure IEE 16th onsite would like a new cable behind quarry tile skirting,
tho some 25x25mm galvanised may change that (over head or on skirting :-)

Since we don't know which, it's wait for the RCD to trip again & discriminate.
Historically, it hasn't and that is why the cables never got done.

Nuisance trips, then someone looks at it, then it never comes back.
I think Butyl suffers insulation creep? All springy but "ductile" stuff. Rubber :-)

Hi,

If the butyl is buried in plaster/stone and there is nothing flammable
nearby you could run a separate earth wire instead of using the one in
the butyl. This is almost certainly Frowned Upon though it would
confirm the problem is in the butyl wire.

As far as running a new T&E wire goes, it could go the least risky way
rather than the most direct way.

cheers,
Pete.

Pete C wrote in message . ..
If the butyl is buried in plaster/stone and there is nothing flammable
nearby you could run a separate earth wire instead of using the one in
the butyl. This is almost certainly Frowned Upon though it would
confirm the problem is in the butyl wire.

No trips since the landing skt was partly unscrewed & refitted,
the electrician re-arranged the wires slightly - respacing them.

As far as running a new T&E wire goes, it could go the least risky way
rather than the most direct way.

Chimney breast is double - gas fire capability on both sides, so
there are gas pipes on both sides and the usual lead of 1960s :-)

Plan of action is thus 2 stage replacement:
o Landing skt - disconnect butyl-radial, so skt on just PVC-T&E-ring
o Other butyl - when breakfast room redecorated all easily redone

Only thing I need to check in advance is the latest IEE regs on cable
routing w.r.t. distance from room edges/floor/ceiling/skirting etc.
I'm sure TLC used to list a pici, but don't seem to anymore.

Thanks.
--
Dorothy Bradbury.

On 1 Oct 2004 15:39:56 -0700, (dorothy)
wrote:


Only thing I need to check in advance is the latest IEE regs on cable
routing w.r.t. distance from room edges/floor/ceiling/skirting etc.
I'm sure TLC used to list a pici, but don't seem to anymore.

Thanks.

It's pretty straightforward.

You can run cables buried in plaster etc. at any depth as long as they
go vertically or horizontally from a wiring accessory.
If for some bizarre reason you wanted to route differently in the
middle of a wall then you must either protect the cable with a serious
protecting plate (grounded) and not thin trunk, or bury at 50mm

You can run cables in a band up to 150mm out from the top of a wall or
from a corner, but not from a floor.


..andy

To email, substitute .nospam with .gl

On 1 Oct 2004 15:39:56 -0700, (dorothy)
wrote:

Pete C wrote in message . ..
If the butyl is buried in plaster/stone and there is nothing flammable
nearby you could run a separate earth wire instead of using the one in
the butyl. This is almost certainly Frowned Upon though it would
confirm the problem is in the butyl wire.

No trips since the landing skt was partly unscrewed & refitted,
the electrician re-arranged the wires slightly - respacing them.

Hi,

Sounds good, I suppose butyl can absorb damp after a long while.

cheers,
Pete.

You can run cables buried in plaster etc. at any depth as long as they
go vertically or horizontally from a wiring accessory.
If for some bizarre reason you wanted to route differently in the
middle of a wall then you must either protect the cable with a serious
protecting plate (grounded) and not thin trunk, or bury at 50mm
You can run cables in a band up to 150mm out from the top of a wall or
from a corner, but not from a floor.

Great, thanks for that - the OSG was out at the library :-)
--
Dorothy Bradbury