Routing Data & Power Wiring to a Server Cabinet


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Old 06-04-14, 12:36 AM
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Routing Data & Power Wiring to a Server Cabinet

I'm in the early stages of planning to build out a cabinet to house my broadband gateway, router, VoIP box and NAS server, with wired Cat 5e connections to the other areas of the house and to a couple of wireless access points, one of which may be outdoors. Obviously I'm going to have to run 115V AC and multiple Cat 5e connections into the same space.

What are the best practices for routing power and data cables in the vicinity of each other to minimize interference? I'm planning a dedicated circuit and a UPS for the electronics, but are there any other precautions I should take for protection of the equipment?

ETA: Note: I wasn't sure whether to post this here or in Communications. I chose this forum because it seemed to have more traffic. Feel free to move if appropriate.
 
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Old 06-04-14, 03:32 AM
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The general rule is to keep the data and power runs a minimum of 12 inches apart and cross them at right angles. Typically they run on opposite sides of a 16" o.c. wall void.
 
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Old 06-04-14, 11:15 AM
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With the current draw that your switches and such will use, coupled with using Cat 5E cables which are reasonably interference-blocking, I wouldn't worry too much about it.

Often times racks and such will be wired with the power up one side and data cabling up the other, keeping the separation as much as possible.
 
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Old 06-04-14, 10:40 PM
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Often times racks and such will be wired with the power up one side and data cabling up the other, keeping the separation as much as possible.
That's actually a very workable idea, since I was planning to mount the center of the cabinet on a stud. I can run the power up one side and the data on the other side of the stud. Thanks.
 
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Old 06-06-14, 04:02 AM
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That will only give you 2 inches of separation. A parallel run over distance is the worst-case scenario because it can cause inductance of power on the data lines.
 
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Old 06-06-14, 11:07 PM
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I should be able to run the power down from the attic and run the data lines up from the crawl space. It will actually be easier to wire that way.
 
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Old 06-11-14, 01:01 PM
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I would say, in my experience working on comm gear that is installed at tower sites, to just make sure that you have a good earth ground run with busbar, and make sure that all of your equipment in the rack (and even the rack itself is grounded to the busbar.
 
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Old 06-13-14, 11:30 PM
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When I first bought the house, I checked the wiring in the room and found it was old 1960's 2-wire fabric covered Romex. I drove a ground rod just outside the room so that I could ground the outlet for my computer. Later I heard that it's not good practice to have a separate isolated ground on power circuits, so as part of the room upgrades and renovation I'm planning to run new 12-2G wire to all of the computer room outlets and see that it's properly grounded back to the panel. That means that the ground rod I drove will be surplus. Would it be a good idea to use this as a ground for the rack and data lines, or would it be better to have the rack and equipment all grounded back to the main service panel and its ground?

ETA: In case this is a consideration, my main electrical service is a drop from overhead utility poles, and there have been occasional outages from lightning strikes in the past. Again, I will be using a UPS and surge suppression, but I thought I'd ask and see if this might be a factor in the decision.
 
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Old 06-15-14, 05:08 AM
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I would abandon the additional ground rod you have. It could be connected, but you'd have to connect it back to your main panel via (likely) 6ga wire.

I would rather spend the time and effort to ensure your main panel is properly grounded and bonded. You want two ground rods 6-8' apart (8' is better) connected via a single (no splices) 6ga copper wire to the ground bus on your main panel. This will provide your best lightning protection, other than use of a UPS. Also make sure your water pipes are bonded similarly, with a jumper across the meter and water heater. This is all current code, but since it sounds like the electrical is older in your house, it's not required - but certainly desired.

You're also making a great decision to run new 12/2 NM-B to have a correctly grounded receptacle.

The UPS is great, but also be sure any other services that connect in are protected as well. I've seen a handful of computers fried even when protected by a UPS when the surge came through the telephone line. (Or nowadays the cable line through the router/network).

-Mike
 
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Old 06-15-14, 07:38 AM
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Interference, meeting code, and doing surge/power protection are three separate issues.

Obviously the earth ground rod was a safety code violation. Grounding anything to water pipes is also a code violation. A grounded receptacle is mostly for human safety reasons. It does little for addressing interference and almost mothing for surge/power protection.

Once common factor for all three is the single point ground.

Rules for routing cables address interference. IOW lightning strikes outside the building should not cause the loss of even one data packet.

Connecting everything and the cabinet to a single point ground at the receptacle addresses both interference and human safety. And does nothing for surge protection.

Surge protection means no surge current must enter the building. Otherwise that current will hunt for earth ground destructivelly via appliances. Once inside, nothing can avert that hunt - especailly not adjacent protectors or a UPS. That protection means all wires entering and being earthed low impedance (ie 'less than 10 feet'). The connection by a hardwire or by a 'whole house' protector. Only then does a surge not enter and go hunting destructively via appliances.

Increasing distance between the cabinet and protector increases protection. Decreasing distance between protector and earth ground electrod increases protection. Upgrading the service entrance earth ground to exceed code requirements increases transistor protection.
 
 

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