Properly grounding a motherboard - in a test environment...

Get your PC tech problems solved here. Quick response time.

Moderator: The Mod Squad

Postby video » Thu Dec 16, 2004 3:19 am

Coppershirt wrote:
kokalo wrote:There are two different types of ground you guys are referring to in this discussion:
* Circuit ground (GND) or the connection to the negative terminal of the PSU/battery, necesary for the operation of the DC electrical circuit it completes.
* Electrical/mains ground of the AC circuit feeding the power supply, also referred to as EARTH, designed for safety.

Since the GND is electrically isolated from the Neutral lead of the mains supply to the PSU by the transformer that also steps down from 110/115/220/230/240V to 12/5/3.3, it would be wrong and dangerous to connect it to Earth




Being an electrical engeineer , in the Uk mains comming to your house , neutral and ground/earth are connected together. This is to emsure you have an electrical safty ground / earth at all times



WHat :lol:

Thats the way a normal circut works, neutral takes it back to the service panel. They are all wired that way if not you would have no flow threw. There is no safty in that, if you get in the middle of that neutral line, you will get killed. The safety is a ground wire, "A fourth wire" just back to the grounding block in the sevice panel. Thats up to code these days. Its the same as 220 years ago, you had 2,110 and 1, neutral (return wire to the service panel) there was and is NO ground in that wiring, yes there is a ground, but that ground is not used just for grounding ( it becomes HOT for the return run to complete the circut, so if you got in the middle of that you would get nailed) No ground that way. Now, there is to be just a ground wire run just for the grounding purpose for the units. I have no Idea what you are into really, but you may have not explained it properly here, or finished what you ment.
video
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1492
Joined: Mon Sep 01, 2003 7:23 pm

Postby gutt3d » Thu Dec 16, 2004 3:21 am

This is great :mrgreen:

Ok - I'm going to try and add something, in agreement with some of the other posts here.

In the UK, a standard PC doesn't need a yellow/green EARTH connection in the plug. The amps drawn at the plug are fairly low (similar to a hi-fi, for example) so you only need a live and neutral connection. (And in theory you should only use 5amp fuse or perhaps less, depending on your PSU). Not exatly how it works, and so I guess the PSU earth connection must go through the neutral pin on the plug.

Tedybear's information makes good sense to me - the case acts to discharge any static that builds up and so prevents component damage caused by ESD.

But at the end of it all, however the PSU is grounded through the plug (must be through the neutral wire) then it doesn't matter how high the voltage (or current is) - if anything got a short circuit to the case it would still be safe to touch the case. Everything goes on a 5 amp fuse coming into the PC, and going out of the PC it is much easier for the current to go via a proper conductor to earth than it would be to try and get through a human body, and their clothes, and their shoes, and then the carpet, and then find a suitable way to earth through the floor.

Quality discussion though 8)

:mb_popcorn:: :mb_popcorn::
gutt3d
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1062
Joined: Wed Aug 18, 2004 3:54 am
Location: Midlands, UK

Postby video » Thu Dec 16, 2004 3:37 am

gutt3d wrote:This is great :mrgreen:

Ok - I'm going to try and add something, in agreement with some of the other posts here.

In the UK, a standard PC doesn't need a yellow/green EARTH connection in the plug. The amps drawn at the plug are fairly low (similar to a hi-fi, for example) so you only need a live and neutral connection. (And in theory you should only use 5amp fuse or perhaps less, depending on your PSU). Not exatly how it works, and so I guess the PSU earth connection must go through the neutral pin on the plug.

Tedybear's information makes good sense to me - the case acts to discharge any static that builds up and so prevents component damage caused by ESD.

But at the end of it all, however the PSU is grounded through the plug (must be through the neutral wire) then it doesn't matter how high the voltage (or current is) - if anything got a short circuit to the case it would still be safe to touch the case. Everything goes on a 5 amp fuse coming into the PC, and going out of the PC it is much easier for the current to go via a proper conductor to earth than it would be to try and get through a human body, and their clothes, and their shoes, and then the carpet, and then find a suitable way to earth through the floor.

Quality discussion though 8)

:mb_popcorn:: :mb_popcorn::



NO, you have no ground unless you have a ground wire,(by itself) NOT the neutral wire, it's not the same, the neutral wire IS ground, BUT it becomes HOT to complete the circut. It's very simple to understand here. YOu need 1 wire to make a circut. one comes as hot to the unit the other wire returns it to the service panel. But IT DOES become HOT to make the run back to the service panel (it IS ONE WIRE, becomes ONE RUN). Now if you get in the middle of that neutral wire YOU become part of the circut, thats when you can get nailed. YOu become what ever is in the wire, you become ONE. There is NO safety in that. You need a ground wire seperate from the circut to be safe. Now I hope that makes sense. Please understand it now. Yes, the neutral wire is not hot from the service panel, but IN a live circut it becomes hot (live). Think about a light bulb. When you put a bulb in the fixture it becomes hot,(that neutral wire) take the bulb out and its dead. I have no Idea how I can take this further here. :)
video
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1492
Joined: Mon Sep 01, 2003 7:23 pm

Postby beaconengr » Thu Dec 16, 2004 5:18 am

Did i say this would be a controversial issue? I have a staff of elecrical engineers, and ground or not to ground seems to always stir this up. Most simply follow the National Electrical Code, even though at times they are adamant that it is wrong.
I still say that for a motherboard, it really doesnt matter. Use metal or plastic, you will be fine either way. As for static, almost all component manuals warn you about discharging static prior to touching any internal components. This should always be standard procedure.
beaconengr
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1135
Joined: Thu Sep 25, 2003 1:41 pm

Postby video » Thu Dec 16, 2004 5:23 am

I never do worry about static, I usually run around the house on carpet with my socks and a sweater on and touch everything I can on the motherboard, just before a build. Just to get it over with. :lol:


I'm waiting for the revenge posts. :lol:
video
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1492
Joined: Mon Sep 01, 2003 7:23 pm

Postby tedybear » Thu Dec 16, 2004 5:31 am

beaconengr wrote:Did i say this would be a controversial issue? I have a staff of elecrical engineers, and ground or not to ground seems to always stir this up. Most simply follow the National Electrical Code, even though at times they are adamant that it is wrong.
I still say that for a motherboard, it really doesnt matter. Use metal or plastic, you will be fine either way. As for static, almost all component manuals warn you about discharging static prior to touching any internal components. This should always be standard procedure.


That statement regarding the motherboard, from my understanding is "correct" as when the motherboard is installed into the case? Around the I/O ports and other connections the earth ground has already been made (that's why the gounding "fingers/prongs" are there. Seems that some of the manufactors used the other redundent grounds as a safty 'net' to provide a large number of earth ground paths in order to prevent most (not all) chances of having prehaps a static discharge toasting parts.

So from a builders perspective you really could go either way? Brass standoff's can deal with the manufactors "redundent" grounds, or use the plastic standoff's and it will use it's own grounds found with such things as the I/O shield and other places. I've always used the brass standoff's as I have no way of knowing what was in the manufactors mind when they did the layouts (as in...how many earth grounds are really needed..Should only take one solid one, but they seem to enjoy using several)

Interesting debate!

S-
tedybear
Black Belt 5th Degree
Black Belt 5th Degree
 
Posts: 7251
Joined: Sat Feb 14, 2004 12:55 am
Location: Fulton, New York, on Earth

Postby Karlsweldt » Thu Dec 16, 2004 5:46 am

Per the Electrical Standards Code Book, the wiring for "residential/consumer" use is as follows: White is a NEUTRAL or return wire; Green is a GROUNDING wire. The ground wire is allowed to have a yellow tracer in the sheath. Black, red, and blue are respective to their phase orientation, in three-phase wiring; Black and red are respective to their orientation, in single-phase wiring. Black is the primary phase, red is the secondary phase. Blue is the third phase. Each leg of a single-phase wire is 180º lagging, compared to the other. In three-phase wiring, each leg is 120º lagging compared to the others. Other colors, such as brown, yellow, violet and orange may be used. They shall be considered as source or control wires.
With computer and most other electronic equipment, the BLACK wire is considered the return lead. The grounding is effected through the black wiring, as well. It is common to both return and ground. Other colors of wires, such as red, yellow, green, white, et al, are considered as source leads.
Within the power supply casing, the black leads all connect to the interior case mounts, which are metallic, forming a positive connection to the case of the power supply. The power supply in turn is mounted securely to the cabinet, forming a shield to reduce EMI and RFI signals. It also supplements the grounding locations for any pertinent equipment, including the motherboard, if so equipped or designed, for specific grounding locations.
Within the power supply casing, also, there is the presence of power from the wall outlet or source, and the wiring code reverts to Standard, being that black is a hot or source lead, brown indicates a hot lead, but is possibly switched. Blue can indicate a return lead, possibly switched. White will indicate a return path, and green will indicate a ground path. The mains or power into the case will be entirely separate from the output, having only the ground as a common tie. There may be a transformer employed as part of the design to reduce/increase voltages as required by the equipment, but most common practice is that the incoming AC voltage is rectified, and stored in capacitors, either in single-stage or two-stage (meaning that one capacitor stores all the DC energy, up to 1.414 RMS the input AC) or in two-stage (two capacitor banks, each storing a positive and negative charge separately), which then is fed to a transistor circuit which "chops" the DC voltage into about 400 Hz to drive a power transformer. This transformer isolates the input source from the output source, entirely. There is NO direct electrical connection between the input power leads and the output power, except for the ground leads.
In the construction of the motherboard or circuit board, there may be requirements of specific grounding points to reduce stray currents, and to shunt the RFI and EMI effects to the case, instead of radiating them to nearby equipment, causing interference. The circuit board may have up to five layers, each having its own "surface" connection points. There are certain "ground" mounts which are at full potential, while others are grounding points through a capacitor or resistor, for a specific purpose.
Operating a motherboard from a computing device outside of its enclosure is allowed for testing and diagnostic purposes, but must be within a fully enclosed metal housing, to be approved for normal use.

The Code Book states the rules, and all must comply to be able to market a device which is considered "safe". This is commonly indicated by the UL letters in a circle, called the "Underwriters Seal".

Brou-Ha-Ha in the making!!

:mb_rulez::
Karlsweldt
Mobo-fu Master
Mobo-fu Master
 
Posts: 20660
Joined: Wed Nov 12, 2003 11:57 am
Location: 07438

Postby beaconengr » Thu Dec 16, 2004 6:12 am

I suggest we vote to make the following recommendation:

Always use metal standoffs, and you will have a proper installation no matter what the manufacturer intended as far as grounding from the mounting points. If he intends for them to be grounded, they will be. If not, the metal rings will be isolated from the motherboard.
beaconengr
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1135
Joined: Thu Sep 25, 2003 1:41 pm

Postby video » Thu Dec 16, 2004 6:59 am

Karlsweldt wrote:Per the Electrical Standards Code Book, the wiring for "residential/consumer" use is as follows: White is a NEUTRAL or return wire; Green is a GROUNDING wire. The ground wire is allowed to have a yellow tracer in the sheath. Black, red, and blue are respective to their phase orientation, in three-phase wiring; Black and red are respective to their orientation, in single-phase wiring. Black is the primary phase, red is the secondary phase. Blue is the third phase. Each leg of a single-phase wire is 180º lagging, compared to the other. In three-phase wiring, each leg is 120º lagging compared to the others. Other colors, such as brown, yellow, violet and orange may be used. They shall be considered as source or control wires.
With computer and most other electronic equipment, the BLACK wire is considered the return lead. The grounding is effected through the black wiring, as well. It is common to both return and ground. Other colors of wires, such as red, yellow, green, white, et al, are considered as source leads.
Within the power supply casing, the black leads all connect to the interior case mounts, which are metallic, forming a positive connection to the case of the power supply. The power supply in turn is mounted securely to the cabinet, forming a shield to reduce EMI and RFI signals. It also supplements the grounding locations for any pertinent equipment, including the motherboard, if so equipped or designed, for specific grounding locations.
Within the power supply casing, also, there is the presence of power from the wall outlet or source, and the wiring code reverts to Standard, being that black is a hot or source lead, brown indicates a hot lead, but is possibly switched. Blue can indicate a return lead, possibly switched. White will indicate a return path, and green will indicate a ground path. The mains or power into the case will be entirely separate from the output, having only the ground as a common tie. There may be a transformer employed as part of the design to reduce/increase voltages as required by the equipment, but most common practice is that the incoming AC voltage is rectified, and stored in capacitors, either in single-stage or two-stage (meaning that one capacitor stores all the DC energy, up to 1.414 RMS the input AC) or in two-stage (two capacitor banks, each storing a positive and negative charge separately), which then is fed to a transistor circuit which "chops" the DC voltage into about 400 Hz to drive a power transformer. This transformer isolates the input source from the output source, entirely. There is NO direct electrical connection between the input power leads and the output power, except for the ground leads.
In the construction of the motherboard or circuit board, there may be requirements of specific grounding points to reduce stray currents, and to shunt the RFI and EMI effects to the case, instead of radiating them to nearby equipment, causing interference. The circuit board may have up to five layers, each having its own "surface" connection points. There are certain "ground" mounts which are at full potential, while others are grounding points through a capacitor or resistor, for a specific purpose.
Operating a motherboard from a computing device outside of its enclosure is allowed for testing and diagnostic purposes, but must be within a fully enclosed metal housing, to be approved for normal use.

The Code Book states the rules, and all must comply to be able to market a device which is considered "safe". This is commonly indicated by the UL letters in a circle, called the "Underwriters Seal".

Brou-Ha-Ha in the making!!

:mb_rulez::



Very nice...I don't have it in me to write all of that to explain, but in the long run and in all the posts, I should have explained it all as you did. nicely done.
video
Black Belt 1st Degree
Black Belt 1st Degree
 
Posts: 1492
Joined: Mon Sep 01, 2003 7:23 pm

Postby colinJohn » Thu Dec 16, 2004 7:08 am

Always use metal standoffs, and you will have a proper installation no matter what the manufacturer intended as far as grounding from the mounting points. If he intends for them to be grounded, they will be. If not, the metal rings will be isolated from the motherboard.


works for me :lol:
"that's some catch that Catch 22"
"It's the best that there is"

Image
colinJohn
Black Belt 3rd Degree
Black Belt 3rd Degree
 
Posts: 3430
Joined: Sat Jul 24, 2004 12:34 pm
Location: UK

PreviousNext

Return to Tech Support

Who is online

Users browsing this forum: Google [Bot] and 5 guests