19” rack cabinet - grounding
Discussion
Just put some rack mount kit into a 12U cabinet. Power distribution (6 sockets) mounted into the rack with a trailing 13a plug to connect it up to the mains.
There’s earth studs on the removable panels and frame. I can run earth wires to these but how should I ground them? Is it enough to rely on the power distribution block’s contact with the frame? Or is there a way to run a ground wire to a plug or something? I know the anti-static plugs can’t be used - anything else?
There’s earth studs on the removable panels and frame. I can run earth wires to these but how should I ground them? Is it enough to rely on the power distribution block’s contact with the frame? Or is there a way to run a ground wire to a plug or something? I know the anti-static plugs can’t be used - anything else?
Just because they’re there doesn’t mean you have to use them.
Back in the old days of analogue a lot of pro kit had the means to separate mains earth from signal earth.
This was to prevent earth loops which resulted in mains hum being heard or seen.
The rack and contents could be earthed such that it was electrically safe whilst keeping mains and signal earth separate to avoid loops and mains borne noise.
Modern kit is a lot better in that respect and is generally more tolerant of earth loops so it’s not really necessary to earth things separate from a signal POV.
Modern electrical installations require extraneous metalwork to be earthed so you’ll often see the rack earthed as a belt and braces measure against faults.
Back in the old days of analogue a lot of pro kit had the means to separate mains earth from signal earth.
This was to prevent earth loops which resulted in mains hum being heard or seen.
The rack and contents could be earthed such that it was electrically safe whilst keeping mains and signal earth separate to avoid loops and mains borne noise.
Modern kit is a lot better in that respect and is generally more tolerant of earth loops so it’s not really necessary to earth things separate from a signal POV.
Modern electrical installations require extraneous metalwork to be earthed so you’ll often see the rack earthed as a belt and braces measure against faults.
you are correct from a signal point of view but from a power point of view it should be grounded, you should not rely on indirect earthing. if an earth post is there and you have mains in and around there and the metal work can be touched id ground it better safe than sorry.
Link the studs with 4mm fitted with crimped eyelets secured using the studs with shake proof washers and nuts. you do have a way to link to earth ? can you securely attach to a secure earth.
Link the studs with 4mm fitted with crimped eyelets secured using the studs with shake proof washers and nuts. you do have a way to link to earth ? can you securely attach to a secure earth.
Is the power distribution specifically designed for rack mounting or just a 6 way extension lead?
If the former these usually have a stud welded to the enclosure for grounding purposes. If the latter then you could wire up a 13A plug with just the earth and use that as the starting point to bond the rack.
Other that is there a water pipe or central heating pipe but not gas that you could bond to using the straps intended for pipes.
If the former these usually have a stud welded to the enclosure for grounding purposes. If the latter then you could wire up a 13A plug with just the earth and use that as the starting point to bond the rack.
Other that is there a water pipe or central heating pipe but not gas that you could bond to using the straps intended for pipes.
gottans said:
Is the power distribution specifically designed for rack mounting or just a 6 way extension lead?
If the former these usually have a stud welded to the enclosure for grounding purposes. If the latter then you could wire up a 13A plug with just the earth and use that as the starting point to bond the rack.
Other that is there a water pipe or central heating pipe but not gas that you could bond to using the straps intended for pipes.
It’s a 6 way 19” rack mount bar with surge protection etc. Can’t see a stud. I did think about just using an ‘earth only’ plug but wasn’t sure of the regs.If the former these usually have a stud welded to the enclosure for grounding purposes. If the latter then you could wire up a 13A plug with just the earth and use that as the starting point to bond the rack.
Other that is there a water pipe or central heating pipe but not gas that you could bond to using the straps intended for pipes.
ruggedscotty said:
you are correct from a signal point of view but from a power point of view it should be grounded, you should not rely on indirect earthing. if an earth post is there and you have mains in and around there and the metal work can be touched id ground it better safe than sorry.
Link the studs with 4mm fitted with crimped eyelets secured using the studs with shake proof washers and nuts. you do have a way to link to earth ? can you securely attach to a secure earth.
No easy way to get to secure earth other than those in the external sockets I want to plug the rack into. Link the studs with 4mm fitted with crimped eyelets secured using the studs with shake proof washers and nuts. you do have a way to link to earth ? can you securely attach to a secure earth.
I might try just connecting to the tails from the studs to the earth pin of a plug, plugged into the 6 way adapter?
dfen5 said:
No easy way to get to secure earth other than those in the external sockets I want to plug the rack into.
I might try just connecting to the tails from the studs to the earth pin of a plug, plugged into the 6 way adapter?
Honestly, don't bother worrying about earthing the rack & especially not the blank panels. Any equipment will be earthed via it's cord (unless it's double insulated) so it's safe.I might try just connecting to the tails from the studs to the earth pin of a plug, plugged into the 6 way adapter?
When installing racks in equipment rooms we run 10/16mm earth cables from the stud in the rack back to a clean earth bar but no-one ever bothers about earthing blank panels. Well actually, the BBC came up with the bright idea of a special cage nut that had a forward facing sharp pointed tab that pierced the paint on the back of the panel but it was deemed a safety hazard to staff as we were cutting ourselves on them & we had to take them all out again.
Funny thing life - ended up having to sort this out at work this week -
rack and radio transmitting equipment for a training exercise.
Ended up discussing this and looking at a way to provide some flying earth leads for clipping onto the RF output when undertaking checks and checks on the antenna - this has to be grounded per procedure before any works can be carried out.
This is what we did.
metal clad double gang socket - fitted a metal earth terminal block onto side of metal clad double gang socket. This also had a plastic cord strain relief grommet fitted. mains cable passed into and wired on to the terminals of the socket. an earth taken from the earth terminal to the back box and a flying lead taken to the metal bolt that protrudes into the socket securing the earth terminal block on the outside. anti shake washers and bolts and washers all used to get a strong solid connection. metal earth terminal block on the socket is then checked to ensure that it has a good connection to earth. flying leads taken from the earth block to the rack and to link the various parts together as required and also provide a flying lead with clip for earthing the antenna.
basically meets what we need but your case may be different.
rack and radio transmitting equipment for a training exercise.
Ended up discussing this and looking at a way to provide some flying earth leads for clipping onto the RF output when undertaking checks and checks on the antenna - this has to be grounded per procedure before any works can be carried out.
This is what we did.
metal clad double gang socket - fitted a metal earth terminal block onto side of metal clad double gang socket. This also had a plastic cord strain relief grommet fitted. mains cable passed into and wired on to the terminals of the socket. an earth taken from the earth terminal to the back box and a flying lead taken to the metal bolt that protrudes into the socket securing the earth terminal block on the outside. anti shake washers and bolts and washers all used to get a strong solid connection. metal earth terminal block on the socket is then checked to ensure that it has a good connection to earth. flying leads taken from the earth block to the rack and to link the various parts together as required and also provide a flying lead with clip for earthing the antenna.
basically meets what we need but your case may be different.
Penelope Stopit said:
Surely there are regulations for earthing all electrical equipment, these are in place to stop skilled people from using a "sod it this will do" approach
Indeed so Penelope, those regulations go towards stopping people getting themselves fried and others too. Its the interpretation of the regs that cause issues - how do you get an earth to an item what changes do you need to make etc, what allowances do you need to make to take into consideration the actual process involved and who is operating the equipment.The earthing / grounding required under normal usage may be completely different to the earthing / grounding required when testing and setting up or undertaking training. The rack were using wont be installed and operated as such on a permanent basis, more as a test training device. hence our need to have bonding across the equipment that will be in use. rack to tuning box and available flying lead to ground out the antenna when working on that.
Back when I used to do computer / server racks, I found that all servers were earthed via the mains plug anyway.
And because the PSU has an earth connection to the chassis, and the chassis is bolted to the rack....
The rack was effectively earthed.
I still used to run an earth bonding strap anyway, however it was largely superfluous if you have more than 2 servers in the rack - even more so if you have a UPS or two mounted in there as well.
When I had a rack at home, I simply ran an earth wire from a 13A plug bonded to the rack - yes, I'm aware it could have been unplugged, however if someone wanted to unplug it, they would have needed to removed the tape and cable ties binding the plug to the socket :P (I'm also aware of the maximum fault current proviso above, however I didn't have much kit in my rack).
And because the PSU has an earth connection to the chassis, and the chassis is bolted to the rack....
The rack was effectively earthed.
I still used to run an earth bonding strap anyway, however it was largely superfluous if you have more than 2 servers in the rack - even more so if you have a UPS or two mounted in there as well.
- all the above assumes one is using a rack wired with a proper PDU etc. and not just an extension plugged into the mains, as the earth bearer needs to be capable of carrying maximum fault current if my memory serves me correctly.
When I had a rack at home, I simply ran an earth wire from a 13A plug bonded to the rack - yes, I'm aware it could have been unplugged, however if someone wanted to unplug it, they would have needed to removed the tape and cable ties binding the plug to the socket :P (I'm also aware of the maximum fault current proviso above, however I didn't have much kit in my rack).
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