welding cable for -48V DC input on an IT equipment?

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vincent21

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Can I use welding cable for an IT device\equipment, to be fed to a 100A circuit breaker? The available power source is -48VDC, and cables will be run on raceway. I'm thinking of using welding cable since it is flexible compared to THHN.
 
vincent21 said:
Can I use welding cable for an IT device\equipment, to be fed to a 100A circuit breaker? The available power source is -48VDC, and cables will be run on raceway. I'm thinking of using welding cable since it is flexible compared to THHN.
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Does it have to comply with the NEC? Is your cable allowed in Art 310?
In addition, the breaker's terminals listed for terminating that cable? Most likely no. If you are even allowed to use that cable because of its very fine stranding you most likely will a crimp type ring tongue terminal listed for that cable remove the exiting terminals on the breaker and the only the ring tongue terminals to the breaker.
I'm sure the you already have selected s breaker that has the DC rating that you need.
 
I do not think there should be any problem with that.Just use right size wire,at least #6.-48DC or the Positive ground communication systems shall work fine with this wire.
 
vincent21 said:
Can I use welding cable for an IT device\equipment, to be fed to a 100A circuit breaker? The available power source is -48VDC, and cables will be run on raceway. I'm thinking of using welding cable since it is flexible compared to THHN.
Click to expand...
It is very common to use welding cable on the communication sites I have worked on. I have never had an inspector look any farther than the service for the shelter since everything inside is pre-fabbed and has a sticker on the door that tells him anything in there is none of his concern.

We always use Chapter 3 wiring to the rectifiers. After that it is whatever is speced/whatever we always do. Never looked at the listing for the lugs we use, I'm sure they are nothing special, YMMV.

Added thought, MTW is more flexible than THHN and may get you where you need to go.
 
ActionDave said:
It is very common to use welding cable on the communication sites I have worked on. I have never had an inspector look any farther than the service for the shelter since everything inside is pre-fabbed and has a sticker on the door that tells him anything in there is none of his concern.

We always use Chapter 3 wiring to the rectifiers. After that it is whatever is speced/whatever we always do. Never looked at the listing for the lugs we use, I'm sure they are nothing special, YMMV.
There are inspectors and there are inspectors.
Added thought, MTW is more flexible than THHN and may get you where you need to go.
Click to expand...

There are inspectors and then again there are inspectors. If the installation is to meets the requirements of the NEC point out where in art 310 the welder's cable, hypalon, and other very fine stranded cable is allowed.
Terminals that are supplied with breakers and contactor's are UL486 and are not listed with that cable either. I'm not aware of any UL486 listed terminals that are listed with other than class B and C stranding. The proper use of UL486 listed terminals is very elusive. I had to actually find a copy of what UL486 to see what the requirements were.
As Jim says "Just because you can, doesn't mean you should."
 
templdl said:
There are inspectors and then again there are inspectors. If the installation is to meets the requirements of the NEC point out where in art 310 the welder's cable, hypalon, and other very fine stranded cable is allowed.
Terminals that are supplied with breakers and contactor's are UL486 and are not listed with that cable either. I'm not aware of any UL486 listed terminals that are listed with other than class B and C stranding. The proper use of UL486 listed terminals is very elusive. I had to actually find a copy of what UL486 to see what the requirements were.
As Jim says "Just because you can, doesn't mean you should."
Click to expand...
Can I sign up for one of your classes?
 
You can find dual listed welding cable that can be used in NEC applications. It will be marked welding cable along with something like "RHH" or some other wire type shown in 310.104. That does nothing to change the termination issue. You will still have to use terminations that are suitable for fine strand conductors.
 
don_resqcapt19 said:
You can find dual listed welding cable that can be used in NEC applications. It will be marked welding cable along with something like "RHH" or some other wire type shown in 310.104. That does nothing to change the termination issue. You will still have to use terminations that are suitable for fine strand conductors.
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Thanks Don
RHH is something that I didn't pick up on. I worked with a few UL OEMs that used hypalon so terminating the cable was the only issue that I have to convince the of. But I did have to address field installation where if I had knowledge of RHH it would have solved those application issues.
 
ActionDave said:
Can I sign up for one of your classes?
Click to expand...
What I've learned is that there is always so much to learn such as the commonly accepted terminal. The terminals are assimled on the devices with no more information than wire size capacities and maybe torque values. But it is difficult to point to a reference for the types of wire other than cl B & C stranded wire that is commonly used.
 
Without examining what using finely stranded wire means for the listing of the breaker, as a practical matter, use of a ferrule at each termination would be good practice. I recently had to use welding cable for a UPS install, as the manufacturer had designed a ridiculously small wiring compartment that THHN wiring would simply not bend in. Where I had to tie into the supply breaker and the lugs on the load-side transformer, I used wire ferrules. The UPS itself had DIN-mount terminal blocks for connection that are designed for use with finely stranded wire. That install has been in place for almost a year, and I recently checked on it and found the connections tight and sound.



SceneryDriver
 
From a practical point of view, welding cable should be fine, it is very widely used for heavy current applications at reduced voltages. Not just for telecoms equipment but also for battery connections, inverters cables and feeders in off grid homes.

It could however be regarded as a violation by a determined inspector, unless you can convince them that it forms part of of the utilisation equipment, and not part of the premises wiring.
 
templdl said:
Does it have to comply with the NEC? Is your cable allowed in Art 310?
In addition, the breaker's terminals listed for terminating that cable? Most likely no. If you are even allowed to use that cable because of its very fine stranding you most likely will a crimp type ring tongue terminal listed for that cable remove the exiting terminals on the breaker and the only the ring tongue terminals to the breaker.
I'm sure the you already have selected s breaker that has the DC rating that you need.
Click to expand...

We definitely have to comply with the NEC because that is part of the engagement with our client. As for the breakers, the site already has miniature circuit breakers on their rectifiers so we just insert the stranded wire, the only wire we have to crimp with ring tongue terminal is the positive side.

Are welding cables categorised as "RHH"? Or is it the battery cables?
 
broadgage said:
From a practical point of view, welding cable should be fine, it is very widely used for heavy current applications at reduced voltages. Not just for telecoms equipment but also for battery connections, inverters cables and feeders in off grid homes.

It could however be regarded as a violation by a determined inspector, unless you can convince them that it forms part of of the utilisation equipment, and not part of the premises wiring.
Click to expand...

That is a nice point. We usually use welding cables on battery connections and rectifiers because of its flexibility. I think we can convinced them that it is for a utilisation equipment.
 
god all mighty i cant believe what im reading,,LOL.....
anyhow,,
You are directed by the NEC to adhear to the most stringent standard.

That would be the Telcordia and GR1275 standards.

your welding cable is not legal in these standards.

you must use RHH/RHW low smoke Class 1 cable.

YOu *could* use DLO ~aka welding cable~ if and only "IF" its identification on the cable itself says "CT rated" , meaing cable tray rated.

Your lugs are easily found from burndy and all your lugs need to end in the part number "FX" indicating flex cable.

a 750mcm STR burny lug will not fit on a 750mcm flex cable. They both have two different colors on the barrel, flex being yellow and str being black.

same for most all the flex wiring, 350mcm str is red barrel while 350mcm flex is blue.

if your trimming off some of the conductors on your cable to get the lug to fit,, then you have the wrong lugs.... just trying to help incase you still have time,, im a little late to this thread.

also, if your cables are laced down side by side, you have instantly eliminated yourself from the middle ground of free air & cable tray wire sizing and you must size cables ampaicty to the "in raceway or cable tray" table

by the way, there is telecommunications facilities and then there are IT people.

Ive never met an IT guy who knew anything about DC power, the faclity power engineer however does.
 
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you need also a properly sized (typically 750mcm or 4/0 green rhh/rhw) dc plant reference ground ran to the faclity main ground bar.
if you do not do this, your aisle grounding will end up haveing current present.

also, i recommend you use non metalic sealtight whips to your rectifier shelves , this is the standard in DC Power because we want "as much as humanly possible" isolate the dc plant from the AC panel board strikes.

your rectifiers have typicall on board metaloxidevaristors to help mitigate any transients but they are only good for an uknown amount of strikes.

you can find the right wire for this at Cobra wire or my supplier Photon communications(ask for rod rainer or ask for ben)
 
well, i can start with 90.2 (b)(4) and or fig 90.3,,, even 90.4

The NEC has tried to wrap its tenticles around the wild mystical and magical thing , taste testing and trying to eat it...
and even though it didnt taste all that bad, now like a sticky bur it cant seem to shake it off.

we tried and tried to tell you, :)

im only speaking to my side of this world, cant speak to the OP or his end customer and thier classification, i can however speak to the correct things to do all things communications related.

no hijack intened,

thanks,

scott
 
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jcassity said:
well, i can start with 90.2 (b)(4) and or fig 90.3,,, even 90.4 ...

scott
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I don't see anything in those sections that even suggest that the NEC requires you to "adhear to the most stringent standard". There may be other standards that apply, but the NEC does not say what you say it says.
 
ActionDave said:
It is very common to use welding cable on the communication sites I have worked on. I have never had an inspector look any farther than the service for the shelter since everything inside is pre-fabbed and has a sticker on the door that tells him anything in there is none of his concern.

We always use Chapter 3 wiring to the rectifiers. After that it is whatever is speced/whatever we always do. Never looked at the listing for the lugs we use, I'm sure they are nothing special, YMMV.

Added thought, MTW is more flexible than THHN and may get you where you need to go.
Click to expand...


I'll look up to that type MTW. Thanks for the suggestion.
 
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