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Wood Racks and Chassis ground

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Anonymous
July 23, 2004 7:07:06 PM

Archived from groups: rec.audio.pro (More info?)

I am racking some audix and telefunken modules in a wood case. Does
anyone have any suggestiuons on what to do with chassis ground. I
don't know if this is dangerous, but I am puting a SPST switch for the
AC line on a MDF front with no connection to ground since it is wood,
as well as other components like pots and audio switches.

Thannks in advance
Anonymous
July 24, 2004 9:57:29 AM

Archived from groups: rec.audio.pro (More info?)

In article <80fadc53.0407231407.1a1d3ad9@posting.google.com> cs@guavatone.com writes:

> I am racking some audix and telefunken modules in a wood case. Does
> anyone have any suggestiuons on what to do with chassis ground. I
> don't know if this is dangerous, but I am puting a SPST switch for the
> AC line on a MDF front with no connection to ground since it is wood,

There's nothing wrong with switching just one side of the line, as
long as it's the hot (not neutral) side.

As far as audio goes, you may find that you get less hum if you
connect the chassis to your common audio ground.

As far as safety goes, if there's a connection between the chassis and
safety ground (the third pin on the power cord) you should maintain
that.

Wood racks are good in the sense that you can isolate one chassis from
the other and have only a single audio ground path, but don't forget
the safety aspect.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
July 24, 2004 12:11:10 PM

Archived from groups: rec.audio.pro (More info?)

>From: cs@guavatone.com (Charles Schaefer)
>Date: 7/23/04 6:07 PM Eastern Daylight Time
>Message-id: <80fadc53.0407231407.1a1d3ad9@posting.google.com>
>
>I am racking some audix and telefunken modules in a wood case. Does
>anyone have any suggestiuons on what to do with chassis ground. I
>don't know if this is dangerous, but I am puting a SPST switch for the
>AC line on a MDF front with no connection to ground since it is wood,
>as well as other components like pots and audio switches.

Are they ungrounded plugs (AC)? If so you can try the old stand by of "tie low
to ground". I'm not all up on your gear so perhaps someone who is will chime
in.
Related resources
Anonymous
July 24, 2004 12:32:22 PM

Archived from groups: rec.audio.pro (More info?)

In article <80fadc53.0407231407.1a1d3ad9@posting.google.com>,
cs@guavatone.com (Charles Schaefer) wrote:

> I am racking some audix and telefunken modules in a wood case. Does
> anyone have any suggestiuons on what to do with chassis ground. I
> don't know if this is dangerous, but I am puting a SPST switch for the
> AC line on a MDF front with no connection to ground since it is wood,
> as well as other components like pots and audio switches.

What's wrong with a grounded metal chassis? Why use wood to avoid it?


Regards,

Monte McGuire
monte.mcguire@verizon.net
Anonymous
July 24, 2004 1:30:43 PM

Archived from groups: rec.audio.pro (More info?)

In article <monte.mcguire-C795D7.04322324072004@news.verizon.net>,
Monte McGuire <monte.mcguire@verizon.net> wrote:
>In article <80fadc53.0407231407.1a1d3ad9@posting.google.com>,
> cs@guavatone.com (Charles Schaefer) wrote:
>
>> I am racking some audix and telefunken modules in a wood case. Does
>> anyone have any suggestiuons on what to do with chassis ground. I
>> don't know if this is dangerous, but I am puting a SPST switch for the
>> AC line on a MDF front with no connection to ground since it is wood,
>> as well as other components like pots and audio switches.
>
>What's wrong with a grounded metal chassis? Why use wood to avoid it?
>
>
>Regards,
>
>Monte McGuire
>monte.mcguire@verizon.net


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 24, 2004 2:40:24 PM

Archived from groups: rec.audio.pro (More info?)

Monte, its a poor man's solution to rackin stuff.


Mike, what do you mean about the safety aspect? this is my caoncern.
Anonymous
July 24, 2004 3:00:05 PM

Archived from groups: rec.audio.pro (More info?)

"Monte McGuire" <monte.mcguire@verizon.net> wrote in message
news:monte.mcguire-C795D7.04322324072004@news.verizon.net
> In article <80fadc53.0407231407.1a1d3ad9@posting.google.com>,
> cs@guavatone.com (Charles Schaefer) wrote:
>
>> I am racking some audix and telefunken modules in a wood case. Does
>> anyone have any suggestiuons on what to do with chassis ground. I
>> don't know if this is dangerous, but I am puting a SPST switch for
>> the AC line on a MDF front with no connection to ground since it is
>> wood, as well as other components like pots and audio switches.
>
> What's wrong with a grounded metal chassis? Why use wood to avoid it?

Good point. Ideally, that power switch would be inside a grounded enclosure,
unless the switch itself had no exposed metal surfaces.
Anonymous
July 24, 2004 3:00:06 PM

Archived from groups: rec.audio.pro (More info?)

I'm still a bit confused. (No wisecracks, Arny.)

I own an Intra "wooden" rack-mount rack. The cabinet is wood, but there are
metal rails to screw the equipment into. This effectively grounds all the
equipment together. Which can be a good or bad thing, depending. (I've seen it
go both ways.)

I don't understand what the problem is. I find it hard to visualize a wooden
cabinet that a piece of rack-mount gear simply slips into -- or has little
bosses for the screws. To paraphrase Alton Brown -- that's not good mountings.
Anonymous
July 24, 2004 4:50:13 PM

Archived from groups: rec.audio.pro (More info?)

"William Sommerwerck" <williams@nwlink.com> wrote in message
news:10g50ug67654ed5@corp.supernews.com

> I'm still a bit confused. (No wisecracks, Arny.)

I hope I didn't contribute to it with my last post!

> I own an Intra "wooden" rack-mount rack. The cabinet is wood, but
> there are metal rails to screw the equipment into. This effectively
> grounds all the equipment together. Which can be a good or bad thing,
> depending. (I've seen it go both ways.)

I guess you're saying that the metal rails are electrically bonded together.

> I don't understand what the problem is.

Is there a problem?

> I find it hard to visualize a
> wooden cabinet that a piece of rack-mount gear simply slips into --
> or has little bosses for the screws.

I've built them.

>To paraphrase Alton Brown -- that's not good mountings.

To quote someone I know, I don't understand what the problem would be with
that.
Anonymous
July 24, 2004 4:50:14 PM

Archived from groups: rec.audio.pro (More info?)

>> I find it hard to visualize a wooden cabinet that a piece
>> of rack-mount gear simply slips into -- or has little bosses
>> for the screws.

> I've built them.

>> To paraphrase Alton Brown -- that's not good mountings.

> To quote someone I know, I don't understand what the problem
> would be with that.

To clarify -- I'm thinking in terms of overall sturdiness, or not having the
unit slip out. That's all. The electrical aspect is not a consideration.
Anonymous
July 24, 2004 5:42:10 PM

Archived from groups: rec.audio.pro (More info?)

I thought I replied but it doesn't show up.


Thanks for all the in depth answers to this.

I basically need something to put the modules and PSU in and I can
make a wood rack ina day or two. a metal one would be big bucks and
timely.

So, If I have a power switch that is metal hooked up to AC-live that
is bad probable since there is no fround connection via chasis on a
metal box?

If I have a plastic switch that may be better right?
Or I could buss the green wire from the 3prong AC to a washer around
the switch. would that make it "safer"?

The power switch is SPST. I was going to use it to break and make the
live connection AC prior to the PSU that is 24VDC for the Audix.
Anonymous
July 24, 2004 9:07:32 PM

Archived from groups: rec.audio.pro (More info?)

On Sat, 24 Jul 2004 08:42:40 -0700, "William Sommerwerck"
<williams@nwlink.com> wrote:

>I don't understand what the problem is. I find it hard to visualize a wooden
>cabinet that a piece of rack-mount gear simply slips into -- or has little
>bosses for the screws. To paraphrase Alton Brown -- that's not good mountings.

Why hard? I can visualise both quite easily - like a nest of
drawers without the drawers.

I'd assumed half the purpose of a wooden rack was to give the user
control over equipment grounding. Or maybe just to be a fashion item
in a contemporary-styled studio (Is wood still "contemporary?)

I used to have an equipment rack with the units hanging vertically off
two wooden runners. No fixings were strictly necessary, but if I
felt the need to locate an item I'd just put in a small wood screw.

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
Anonymous
July 24, 2004 10:38:22 PM

Archived from groups: rec.audio.pro (More info?)

William Sommerwerck <williams@nwlink.com> wrote:
>I'm still a bit confused. (No wisecracks, Arny.)
>
>I own an Intra "wooden" rack-mount rack. The cabinet is wood, but there are
>metal rails to screw the equipment into. This effectively grounds all the
>equipment together. Which can be a good or bad thing, depending. (I've seen it
>go both ways.)
>
>I don't understand what the problem is. I find it hard to visualize a wooden
>cabinet that a piece of rack-mount gear simply slips into -- or has little
>bosses for the screws. To paraphrase Alton Brown -- that's not good mountings.

He is building a box that has some old modules stripped out of a console,
with a flat front plate and holes so that it can be mounted into a rack.
He is using MDF for this for some reason, which seems a little weird to me
but not too terrible.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 24, 2004 10:43:02 PM

Archived from groups: rec.audio.pro (More info?)

Charles Schaefer <cs@guavatone.com> wrote:
>I basically need something to put the modules and PSU in and I can
>make a wood rack ina day or two. a metal one would be big bucks and
>timely.

I dunno, it would seem a lot easier to make a good metal one than a good
wood one. You buy a premade front panel, cut some holes out of it, and
use some aluminum L-bracket to mount the modules.

>So, If I have a power switch that is metal hooked up to AC-live that
>is bad probable since there is no fround connection via chasis on a
>metal box?

As long as the switch doesn't fail in a bad way that makes the switch
case live, it's fine. I have not seen that happen before but it could
happen.

>If I have a plastic switch that may be better right?
>Or I could buss the green wire from the 3prong AC to a washer around
>the switch. would that make it "safer"?
>
>The power switch is SPST. I was going to use it to break and make the
>live connection AC prior to the PSU that is 24VDC for the Audix.


You worry too much.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 24, 2004 10:43:03 PM

Archived from groups: rec.audio.pro (More info?)

>> The power switch is SPST. I was going to use it to break and make
>> the live connection AC prior to the PSU that is 24VDC for the Audix.

> You worry too much.

Agreed. But if you're going to switch the line, you should use a double-pole
switch and switch both the hot and neutral. It's safer that way.
Anonymous
July 24, 2004 11:59:40 PM

Archived from groups: rec.audio.pro (More info?)

"William Sommerwerck" <williams@nwlink.com> wrote in message
news:10g5cnc11n87qe1@corp.supernews.com
>>> I find it hard to visualize a wooden cabinet that a piece
>>> of rack-mount gear simply slips into -- or has little bosses
>>> for the screws.
>
>> I've built them.
>
>>> To paraphrase Alton Brown -- that's not good mountings.
>
>> To quote someone I know, I don't understand what the problem
>> would be with that.
>
> To clarify -- I'm thinking in terms of overall sturdiness, or not
> having the unit slip out. That's all. The electrical aspect is not a
> consideration.

Oak is pretty strong stuff. T-nuts are pretty tenacious.
Anonymous
July 25, 2004 12:15:20 AM

Archived from groups: rec.audio.pro (More info?)

In article <10g50ug67654ed5@corp.supernews.com> williams@nwlink.com writes:

> I own an Intra "wooden" rack-mount rack. The cabinet is wood, but there are
> metal rails to screw the equipment into.

> I don't understand what the problem is. I find it hard to visualize a wooden
> cabinet that a piece of rack-mount gear simply slips into -- or has little
> bosses for the screws. To paraphrase Alton Brown -- that's not good mountings.

When I had my remote truck, I mounted some rack-mount gear in wood
because it saved space over using rack cabinets. I had a pair of
vertically mounted 2x2s spaced the "gear width" apart, with T-nuts to
catch the screws. Nice and solid, and gave me a couple of extra
inches. I never had a problem with chassis that touched an adjacent
one, or not.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
July 25, 2004 12:15:21 AM

Archived from groups: rec.audio.pro (More info?)

In article <80fadc53.0407240940.5da9256d@posting.google.com> cs@guavatone.com writes:

> Mike, what do you mean about the safety aspect? this is my caoncern.

I wasn't quite sure what you were really doing. The "safety aspect" is
that equipment in a metal case usually has the case connected to the
electrical safety ground (the third pin on the power plug) so that if
the hot side of the AC touches the case, it will return to neutral
through the safety ground, tripping a circuit breaker on the way, and
the chassis won't be electrically "hot."

If the equipment is in a wooden box so there's no way you could touch
the chassis, then it's safe. However, if the chassis is connected,
either throgh rack rails or through a cable shield, to another
chassis, then that other chassis could become AC-hot in the event of a
short in the "insulated" chassis.

Portable power tools and home appliances are often "double insulated"
and have no safety ground. There's no way you can contact anything
that the hot AC lead can touch, so there's no risk of electrical
shock. And, plastic being cheaper than copper, this is a way to save
money.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
July 25, 2004 12:15:22 AM

Archived from groups: rec.audio.pro (More info?)

In article <80fadc53.0407241242.3c32c7c8@posting.google.com> cs@guavatone.com writes:

> I basically need something to put the modules and PSU in and I can
> make a wood rack ina day or two. a metal one would be big bucks and
> timely.
>
> So, If I have a power switch that is metal hooked up to AC-live that
> is bad probable since there is no fround connection via chasis on a
> metal box?

Why not just use a switched outlet strip? They're cheap, UL approved
(safe) and you need a place to plug all that stuff in to anyway.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
July 25, 2004 12:15:23 AM

Archived from groups: rec.audio.pro (More info?)

> Why not just use a switched outlet strip? They're cheap, UL-approved
> (safe) and you need a place to plug all that stuff in to anyway.

I was once warned by a fire inspector about cheap outlet strips. It seems their
circuit breakers can actually _cause_ fires.

The reason? Some cheap breakers have a fairly high resistance. If you pull
enough amps through them (though not enough to trip the breaker), the breaker
will overheat and burst into flames.

I hate it when that happens.

Note that this is not an inherent problem with circuit breakers (per se), but
with badly designed or manufactured breakers.
Anonymous
July 25, 2004 1:56:29 AM

Archived from groups: rec.audio.pro (More info?)

On 24 Jul 2004 13:42:10 -0700, cs@guavatone.com (Charles Schaefer)
wrote:

>I basically need something to put the modules and PSU in and I can
>make a wood rack ina day or two. a metal one would be big bucks and
>timely.

Do they have Dexion where you live?
Though wood's nicer :-)

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
Anonymous
July 25, 2004 11:27:59 PM

Archived from groups: rec.audio.pro (More info?)

In article <10g60nmaj09uiae@corp.supernews.com> williams@nwlink.com writes:

> I was once warned by a fire inspector about cheap outlet strips. It seems their
> circuit breakers can actually _cause_ fires.

So buy a better one. Anything that's UL approved isn't a fire risk.
The risk with outlet strips is that they use a varistor for surge
suppression. Each surge that it suppresses weakens the component, and
eventually it won't be a surge suppressor any more. Seems like I
remember that some of the surge suppressor outlet strips from 20 years
ago were reported to arc over, but I haven't heard about that in
years.

Besides, fire inspectors get worried about things like this that, in a
typical home, get stashed behind a couch or bookcase, possibly with
curtains hanging directly over it, and nobody looks at it for 20
years. That's a fire hazard.

If you get an approved outlet strip and mount it on the back of your
wood cabinet where you can reach the switch, you'll have no problem.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
July 26, 2004 5:45:31 PM

Archived from groups: rec.audio.pro (More info?)

In article <znr1090753243k@trad>, Mike Rivers <mrivers@d-and-d.com> wrote:
>In article <10g60nmaj09uiae@corp.supernews.com> williams@nwlink.com writes:
>
>> I was once warned by a fire inspector about cheap outlet strips. It seems their
>> circuit breakers can actually _cause_ fires.
>
>So buy a better one. Anything that's UL approved isn't a fire risk.
>The risk with outlet strips is that they use a varistor for surge
>suppression. Each surge that it suppresses weakens the component, and
>eventually it won't be a surge suppressor any more. Seems like I
>remember that some of the surge suppressor outlet strips from 20 years
>ago were reported to arc over, but I haven't heard about that in
>years.

There was a serious problem about a decade ago with a particular series
of SL Waber power strips (NOT surge suppressors) which were unfortunately
supplied by Rolm along with their telephone systems. The internal connections
were poorly crimped, and could present a fire hazard. The solution to this
is to pop the back and solder all of the crimped lines on the back of each
outlet. But again, this was a manufacturing defect and not at all a problem
with the idea of power strips.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 28, 2004 4:15:00 PM

Archived from groups: rec.audio.pro (More info?)

My understanding is that solder is not used in electrical connections
because of the possible heat these line can see. If they get hot and
the solder melts bigger problems will occur. I think perhaps a better
crimp or wire nut should be used.

Scott Dorsey wrote:

> In article <znr1090753243k@trad>, Mike Rivers <mrivers@d-and-d.com> wrote:
>
>>In article <10g60nmaj09uiae@corp.supernews.com> williams@nwlink.com writes:
>>
>>
>>>I was once warned by a fire inspector about cheap outlet strips. It seems their
>>>circuit breakers can actually _cause_ fires.
>>
>>So buy a better one. Anything that's UL approved isn't a fire risk.
>>The risk with outlet strips is that they use a varistor for surge
>>suppression. Each surge that it suppresses weakens the component, and
>>eventually it won't be a surge suppressor any more. Seems like I
>>remember that some of the surge suppressor outlet strips from 20 years
>>ago were reported to arc over, but I haven't heard about that in
>>years.
>
>
> There was a serious problem about a decade ago with a particular series
> of SL Waber power strips (NOT surge suppressors) which were unfortunately
> supplied by Rolm along with their telephone systems. The internal connections
> were poorly crimped, and could present a fire hazard. The solution to this
> is to pop the back and solder all of the crimped lines on the back of each
> outlet. But again, this was a manufacturing defect and not at all a problem
> with the idea of power strips.
> --scott
Anonymous
July 28, 2004 4:15:01 PM

Archived from groups: rec.audio.pro (More info?)

> My understanding is that solder is not used in electrical connections
> because of the possible heat these line can see. If they get hot and
> the solder melts bigger problems will occur. I think perhaps a better
> crimp or wire nut should be used.

Ever seen a wire nut? Billions of them have been used over the past 75 years.
Quite reliable.
!