Bending radius and spacing between equipment's

A

Akten

Member
Location
New York
Occupation
Engineer
Hi,

I am trying to figure out distance between 2 equipment's (service disconnect and meter). I think wire bending radius is the key factor to this. If I have a 3x 500MCM cables (1 for each phase for 480V system) coming out from the bottom of the disconnect, and entering the bottom of meter enclosure, how much spacing do I need between them?

My calculation is:
Assume XHHW-2 wire, single conductor OD for 500mcm is 0.93 inch (based on one cable cut sheet I saw). Bending radius of 6 based on google (I only saw a clause in NEC for above 1000V but not sure if NEC has a bending radius requirement for below 1000V)

1x500mcm : OD = 0.93inch
Bending radius = 6*0.93 = 5.58inch
Spacing required for U shaped cable installation (coming out from bottom of disconnect to bottom of meter): 2*bending radius = 12.48 inches

If the above is correct and is the bending radius for single conductor, then do I have to multiple the spacing by 3 for 3 conductor runs? That would seem a little too much, so I would like to understand how to go about with this.
 
The code has no bending radius requirements for single conductors rated 1000 volts or less.
However it does have bending radius requirements for cables rated 1000 volts or less. Those are based on the OD of the cable and are found in the xxx.24 sections of the cable articles. That bending radius is applied to the OD of the cable.
What cable are you using and what is its OD?
 
As Dodn stared you can bend those conductors as sharp as you want. There are minimum spacing distances for the terminals in equipment.
 
don_resqcapt19 said:
The code has no bending radius requirements for single conductors rated 1000 volts or less.
However it does have bending radius requirements for cables rated 1000 volts or less. Those are based on the OD of the cable and are found in the xxx.24 sections of the cable articles. That bending radius is applied to the OD of the cable.
What cable are you using and what is its OD?
Click to expand...
By cable, do you mean raceway? I was trying to assume calculation using XHHW insulation wire, 500MCM, so 3x500mcm XHHW for 3 phase system.
 
Akten said:
By cable, do you mean raceway? I was trying to assume calculation using XHHW insulation wire, 500MCM, so 3x500mcm XHHW for 3 phase system.
Click to expand...
XHHW does not have a minimum bending radius. So as Jim mentioned the listed equipment will have the required bending space for the terminals. If you're asking because you're manufacturing the equipment then those minimum terminal space rules would apply. Can you show a sketch of what you're proposing?
 
infinity said:
XHHW does not have a minimum bending radius. So as Jim mentioned the listed equipment will have the required bending space for the terminals. If you're asking because you're manufacturing the equipment then those minimum terminal space rules would apply. Can you show a sketch of what you're proposing?
Click to expand...
Attached a sketch (not the best), but basically, I was asking if I want to install 2 equipments side by side, how much spacing I should give between them, I could only think of bending radius of wires being the factor to consider (3x500MCM for example, and assuming the incoming and outgoing wiring is from bottom of each enclosure)

1741290327804.png
 
What is connecting to two pieces together? If you're running a circular raceway like in your sketch you'll need to space them far enough apart so that the sweep of the elbows will fit. Otherwise a conduit body or wireway would allow for less space between the two pieces of equipment.
 
Akten said:
By cable, do you mean raceway? I was trying to assume calculation using XHHW insulation wire, 500MCM, so 3x500mcm XHHW for 3 phase system.
Click to expand...
No, I mean a cable with multiple conductors and an outer jacket.
If you are installing in a conduit type raceway, there are minimum bending radii for the conduit itself.
 
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