Distribution Panel vs Switchboard

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New EE

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California
Sorry if this is a dumb question...when is it considered to be a switchboard compared to a distribution panel? Is there a certain amperage when it's considered a switchboard? Thanks. I've heard distribution panels being called switchboards when I was thinking it was a distrubution panel. So I get confused sometimes.
 

Npstewart

Senior Member
Look up the definition for a switched board in article 100. I dont think there is a definition for a distribution panel.

Article 100
"a large single panel, frame, or assembly of panels on which
are mounted, on the face or back, or both, switches, overcurrent
and other protective devices, buses, and usually instruments.
Switchboards are generally accessible from the rear as well as
from the front and are not intended to be installed in cabinets"
 

Mike01

Senior Member
Location
MidWest
DP vs SW BD

DP vs SW BD

Usually when you get to the 1200-1600A ranges you are looking at switchboard, but the differences are the physical space requirements switchboards will take up more re-estate and sometimes depending on the size configuration or project specifications may require rear access (not in all cases) as well as front access, where a distribution panels is usually around 12" deep and always front access. The two are also constructed to different UL standards panel board to the panel board standard and switchboard to UL-891. You can also get switchgear built with 30cycle busing I have see this lately also. The switchboard will allow you to get into the insulated case breaker world one step above molded case one below low voltage power circuit breakers. Switchboards also contain horizontal bussing to each section as opposed to cabling between each section. If you go to any manufacturers website (Eaton, square d, or GE) you can see panel boards vs switchboards vs switchgear, they all have their advantages over one another but keep in mind cost escalades with the type of gear, so it can also be a project specific budget driven issue. Hope this helps.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Different UL classifications and NEC restrictions basically.

Panelboards are designed and tested under UL67, Switchboards are defined under UL891. The basic difference is in what they are INTENDED to be used for and how they are mounted. A Panelboard can be a Lighting and Appliance Panelboard, in which case it is limited to 42 circuits, or a Power Distribution Panelboard which is not. Both have a basic design requirement of being completely front accessible so they can be mounted on or in a wall without rear access. This essentially limits the power handling capabilities because at some point when the bus bars get huge, it becomes impractical to have to remove units to check for bolt torque etc. in an environment that has PM procedures.

Enter Switchboards, which do not have the front access only restriction. You are allowed to build a Switchboard so that you need rear access to perform PM tasks. So basically when the bus bars get big, the likelihood of being able to use a Panelboard becomes less. And if an industrial facility has a PM program (because for industrials, it's all about up-time), then you will often see Switchboards specified even if a Panelboard might have worked.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
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