Short Circuit Rating of a Receptacle

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ron

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Designing a datacenter which will have a lot of fault current available through the distribution path down to the receptacle that the IT equipment will plug into. Values at the receptacle are >5kA. Since a receptacle doesn't have a short circuit or withstand rating, do I just ignore it?

This would be the same situation if you had a receptacle installed from a panelboard branch circuit installed in the main switchgear room. If the main SWGR requires 65kA or 100kA, and the panelboard is on an adjacent wall, and the #12 wire is less than a few feet from the panelboard, the calculated fault current will be high there too.

Has anyone contemplated this issue?
 

charlie b

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I have never calculated the short circuit current any further down the line than the branch circuit panel.
 

fmtjfw

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UL508A

UL508A

Supplement SB of UL 508A, a Receptacle (other than GFCI type) has a
default SCCR rating of 10kA when unmarked and not documented in instructions from the Manufacturer.
 

petersonra

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OK, but does that effect the short circuit rating of an receptacle?


110.10 Circuit Impedance, Short-Circuit Current Ratings,
and Other Characteristics. The overcurrent protective
devices, the total impedance, the equipment shortcircuit
current ratings, and other characteristics of the
circuit to be protected shall be selected and coordinated to
permit the circuit protective devices used to clear a fault to
do so without extensive damage to the electrical equipment
of the circuit. This fault shall be assumed to be either between
two or more of the circuit conductors or between any
circuit conductor and the equipment grounding conductor(
s) permitted in 250.118. Listed equipment applied in
accordance with their listing shall be considered to meet the
requirements of this section
.

Note carefully what it says. As long as a listed device is applied within its ratings it is considered to meet the requirement. I have not seen any receptacle instructions that mention SCCR at all, so it just is not a factor with receptacles as far as I am concerned, unless it is in a power circuit of a UL508a industrial control panel.
 
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jim dungar

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The links I cite all mention 10K SCCR for standard outlets.
No they really don't.

The Schneider Electric link, is to an assembly which happens to contain a receptacle. The overall assembly is rated 10kA. This limit may be due to the breaker as much as it is to the receptacle.
The Grace link is simply a reprint of a table from UL508A.
 

kwired

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I question if the IT equipment that is plugged in should be installed where the available fault current is over 5kA, I don't know either way but think it needs further investigation, if that answer is no then that kind of makes the question of the receptacle pointless to further consider - unless the cords are pretty long and end up reducing the current before it hits the equipment, but if that is the case, why such long cords?
 

templdl

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No they really don't.

The Schneider Electric link, is to an assembly which happens to contain a receptacle. The overall assembly is rated 10kA. This limit may be due to the breaker as much as it is to the receptacle.
The Grace link is simply a reprint of a table from UL508A.

Jim, you set me straight in SCCR and withstand a while back when I should have known better. With receptacle it isn't an interrupting device so wouldn't a withstand rating be applicable? And I really can't see any withstand rating being available for them.
 

petersonra

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jim dungar

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Jim, you set me straight in SCCR and withstand a while back when I should have known better. With receptacle it isn't an interrupting device so wouldn't a withstand rating be applicable? And I really can't see any withstand rating being available for them.

For the vast majority of situations the terms SCCR and withstand can be used interchangeably. They both deal with equipment being able to tolerate fault currents until some upstream device operates. I believe SCCR is consider 'contemporary' while withstand is somewhat 'archaic'.

It is AIC (amps interrupting capacity) that is usually missed used. AIC is specific to protective devices.

I would not be surprised that there is an actual SCCR for receptacles, but I have never seen one (except for those that contain electronics).
 

fmtjfw

Senior Member
The Leviton link does not work.

I would suggest if you use these they would need to be on a circuit capable of delivering not more than 10kA of SCC.

The Link works for me, if I click on it. It is abbreviated as displayed by the forum software, so if you copy it and try to use it it fails.
 

Dennis Alwon

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Jraef

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Note carefully what it says. As long as a listed device is applied within its ratings it is considered to meet the requirement. I have not seen any receptacle instructions that mention SCCR at all, so it just is not a factor with receptacles as far as I am concerned, unless it is in a power circuit of a UL508a industrial control panel.

That's the issue. Initially, "Short-Circuit Current rating", as a term in the NEC, was only mentioned in Article 409, which is SPECIFIC to Industrial Control Panels. In the 2011 they now use the term when discussing Service Equipment, SPDs and motor controllers, in addition to Article 110 as shown above. But as pointed out if the device is used as listed, it is acceptable.

I got into this discussion with Google engineers a couple of years ago as we were designing their server racks, the final outcome was that we didn't need to worry about it, they are not considered Industrial Control Panels. That was prior to the 2011 code release, but I don't see anything that substantially changes that.
 

templdl

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Location
Wisconsin
For the vast majority of situations the terms SCCR and withstand can be used interchangeably. They both deal with equipment being able to tolerate fault currents until some upstream device operates. I believe SCCR is consider 'contemporary' while withstand is somewhat 'archaic'.

It is AIC (amps interrupting capacity) that is usually missed used. AIC is specific to protective devices.

I would not be surprised that there is an actual SCCR for receptacles, but I have never seen one (except for those that contain electronics).

Again, I conceed Jim. I had AIC implanted on my mind and I do know better. If there was an SCCR for the device in question it would be interest to know what it would be. Doing a SCCR coordination study that would include such devices may be very interesting.
 

ron

Senior Member
I would not be surprised that there is an actual SCCR for receptacles, but I have never seen one (except for those that contain electronics).

There is an inherent SCCR for receptacles but nobody in the market except very few exceptions are required to test and or publish. Plug strips may come with in input CB, but that shouldn't lead anyone to beleive that it has anything to do with the SCCR of the plugstrip. You can buy plugstrips with 5kA or 10kA breakers or 100kA fuses, but the plug strip never gets tested to esablish if the assembly has any rating.
 
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