Can anybody point me at info about the (regulations? suggestions? new-best-practice?) concerning use and wiring of circuits with dual or clean earth connections for IT equipment?
Regds.,
Mike
Regds.,
Mike
Dual/Clean earth
- Thread starter ban-all-sheds
- Start date
Sponsored Links
B
breezer
as far as i know they are wired the same, to the same regulations as every thing elses, except they have a clean earth.
Why would you require 2 earths? I have had a word with my good lady wife, who is an IT tech. And she has never heard of it. Also there could be a problem if the mains is wired with the neutrals connected to earth ( is it multiple safe earths or something like that ) If you then put a proper earth in it could be hazardous if the neutral back to the substation went open circuit...
Here's an example of why I was asking:
//www.diynot.com/shop/Electrical/Surge_Sockets/SURGE_FILTER_CLEA_EARTH_2G_SKT/3998
From which I quote: "Dual earth model covers new regulations governing 'IT' installations requiring clean earth."
As for connecting neutral to earth - although I'm not an expert electrician, from what I understand I guess you're talking about Protective Multiple Earth (PME) (See http://www.tlc-direct.co.uk/Book/5.6.1.htm for a handy on-line guide). It would seem that this is an unusual type of supply, with all sorts of special requirements at the installation end, and if you get a break in the neutral, you and all your neighbours are in a world of trouble.
//www.diynot.com/shop/Electrical/Surge_Sockets/SURGE_FILTER_CLEA_EARTH_2G_SKT/3998
From which I quote: "Dual earth model covers new regulations governing 'IT' installations requiring clean earth."
As for connecting neutral to earth - although I'm not an expert electrician, from what I understand I guess you're talking about Protective Multiple Earth (PME) (See http://www.tlc-direct.co.uk/Book/5.6.1.htm for a handy on-line guide). It would seem that this is an unusual type of supply, with all sorts of special requirements at the installation end, and if you get a break in the neutral, you and all your neighbours are in a world of trouble.
Sponsored Links
I wonder where we can get a butchers at these new regs.
Ann ( wife) says all there important stuff runs on UPS so surges etc are not a problem cos there arnt any.. All the other machines are on standard ring mains with trip switches.
If you want to protect you computer gear get a ups.
Shes on the sick at the moment but says she will look into this when the college resumes for business next week.
Ann ( wife) says all there important stuff runs on UPS so surges etc are not a problem cos there arnt any.. All the other machines are on standard ring mains with trip switches.
If you want to protect you computer gear get a ups.
Shes on the sick at the moment but says she will look into this when the college resumes for business next week.
- Joined
- 1 Sep 2003
- Messages
- 82
- Reaction score
- 0
- Country
I wonder if this is what you are referring to...? I reckon it is
There is a regulation that applies to ring circuits which are used to supply computer equipment (eg PCs). It is in place because PCs are notorious for having earth leakage, so this guarantees an effective earth.
The regulation states that the socket outlets used on the ring circuits should have two earth connections on the back, not just the usual one (though the wo are joined together at the back of the socket). Then the two earths from the ring cables are each put into one of these. This is so that if one connection should work loose and come out, there will still be an earth connection, even though the ring continuity is broken. In normal outlets with one earth connector, then both earth wires could come out and the appliance would be unearthed.
Have fun..
Paul
There is a regulation that applies to ring circuits which are used to supply computer equipment (eg PCs). It is in place because PCs are notorious for having earth leakage, so this guarantees an effective earth.
The regulation states that the socket outlets used on the ring circuits should have two earth connections on the back, not just the usual one (though the wo are joined together at the back of the socket). Then the two earths from the ring cables are each put into one of these. This is so that if one connection should work loose and come out, there will still be an earth connection, even though the ring continuity is broken. In normal outlets with one earth connector, then both earth wires could come out and the appliance would be unearthed.
Have fun..
Paul
- Joined
- 1 Sep 2003
- Messages
- 82
- Reaction score
- 0
- Country
Regulation 607 of BS 7671 (the IEE Wiring Regulations) states that if you are using double sockets on a Ring circuit where earth leakage can occur, you must use sockets with twin earths, and connect each earth seperately in the consumer unit.
I'm slightly out of date (been off the tools for 3 years). It actually appears now that even then this is only acceptable if listed as a deviation on the test report. You should actually only use single sockets preferably, and should only use one appliance per socket (ie no trailing leads).
Rather than me waffle on in depth, have a look at the this article - www.cda.org.uk/megab2/elecapps/pub142lo.pdf - it says it refers to domestic, but the principles are the same, the document is just pointing out it may also apply to houses because of the number of computers used.
I'm slightly out of date (been off the tools for 3 years). It actually appears now that even then this is only acceptable if listed as a deviation on the test report. You should actually only use single sockets preferably, and should only use one appliance per socket (ie no trailing leads).
Rather than me waffle on in depth, have a look at the this article - www.cda.org.uk/megab2/elecapps/pub142lo.pdf - it says it refers to domestic, but the principles are the same, the document is just pointing out it may also apply to houses because of the number of computers used.
- Joined
- 1 Sep 2003
- Messages
- 82
- Reaction score
- 0
- Country
No problem, glad it helped.
As a last note, what you said earlier was correct, that a UPS is a very good idea to protect any important equipment, because even good earthing won't prevent power spikes etc.
Have a good one
Paul
As a last note, what you said earlier was correct, that a UPS is a very good idea to protect any important equipment, because even good earthing won't prevent power spikes etc.
Have a good one
Paul
I think a "clean earth" is not section 607, but something else again.
Try looking at the diagrams here:
http://www.aelgroup.co.uk/hb/hb022.pdf
This page may also be useful:
http://www.aelgroup.co.uk/hb/hb008.pdf
Although it seems it's easy to get wrong:
http://www.marcspages.co.uk/pq/3353.htm.
As an aside, I quite liked this page:
http://www.aelgroup.co.uk/hb/hb001.htm
"Although simple in concept the CVT is very difficult to explain, leading to some electronics experts to describe it as magic."
Try looking at the diagrams here:
http://www.aelgroup.co.uk/hb/hb022.pdf
This page may also be useful:
http://www.aelgroup.co.uk/hb/hb008.pdf
Although it seems it's easy to get wrong:
http://www.marcspages.co.uk/pq/3353.htm.
As an aside, I quite liked this page:
http://www.aelgroup.co.uk/hb/hb001.htm
"Although simple in concept the CVT is very difficult to explain, leading to some electronics experts to describe it as magic."
Clean earths provide a seperate earthig conductor right back to the supply for sockets for computers.
You can get sockets with a funny shaped eart hpin to stop people plugging in kettles to the clean sockets.
You could wire a radial to several sockets, intended just for computers, this would already be a clean earth, as nothing else would share the earth in that circuit.
If you just want to make 4 sockets on a ring into clean earth sockets, use a socket outlet with a clean earth terminal. These have an earth terminal for the accessory screws which you connect the ring earths to, and a seperate earth terminal for the pins which you connect your clean earth to.
Dont get clean earth sockets confused with dual earth sockets - all wholesalers do A DUAL earth socket simply has two earth terminals on the same earth bar, and this is used for the reg concerning high protective conductor currents.
Clean earths are not installed nowadays due to decent filtering packs, and UPS's. DUAL earth-high protective conductor current circuits ARE (or should) be installed where a number of computers share a circuit.
You can get sockets with a funny shaped eart hpin to stop people plugging in kettles to the clean sockets.
You could wire a radial to several sockets, intended just for computers, this would already be a clean earth, as nothing else would share the earth in that circuit.
If you just want to make 4 sockets on a ring into clean earth sockets, use a socket outlet with a clean earth terminal. These have an earth terminal for the accessory screws which you connect the ring earths to, and a seperate earth terminal for the pins which you connect your clean earth to.
Dont get clean earth sockets confused with dual earth sockets - all wholesalers do
A DUAL earth socket simply has two earth terminals on the same earth bar, and this is used for the reg concerning high protective conductor currents.Clean earths are not installed nowadays due to decent filtering packs, and UPS's. DUAL earth-high protective conductor current circuits ARE (or should) be installed where a number of computers share a circuit.
There are two issues here. High security earthing, already alluded to, for circuits with high earth leakage (10mA or more).
I mean this http://www.tlc-direct.co.uk/Book/7.8.2.htm as an example.
The other is a clean or functional earth, in the radio interference sense, for computers remember that a system that radiates interference is more vulnerable to pick-up interference and network errors and crashes from spikes induced by lightning etc. The functional earth is generally not considered by the wiring regs, but is the domain of other specialists.
There is a lot more info about this in the telecommunications and radio press than the computing/IT, where I think it is a new-ish consequence of newer equipment running at speeds that are really so high as to behave like radio frequencies. Here one needs a book like the Radio Amateurs guide to EMC, although this is really about radio installations, with computers as a side-chapter.
As already suggested, normally at least, stand alone machines are best filtered locally, and treated like ordinary appliences, its just that the capacitors in the filters lead to a small, but steady earth current, which if there are a number of machines, requires a high integrity rearth connection.
M.
I mean this http://www.tlc-direct.co.uk/Book/7.8.2.htm as an example.
The other is a clean or functional earth, in the radio interference sense, for computers remember that a system that radiates interference is more vulnerable to pick-up interference and network errors and crashes from spikes induced by lightning etc. The functional earth is generally not considered by the wiring regs, but is the domain of other specialists.
There is a lot more info about this in the telecommunications and radio press than the computing/IT, where I think it is a new-ish consequence of newer equipment running at speeds that are really so high as to behave like radio frequencies. Here one needs a book like the Radio Amateurs guide to EMC, although this is really about radio installations, with computers as a side-chapter.
As already suggested, normally at least, stand alone machines are best filtered locally, and treated like ordinary appliences, its just that the capacitors in the filters lead to a small, but steady earth current, which if there are a number of machines, requires a high integrity rearth connection.
M.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
