I was once asked by a Foreman:"What's The Difference Between A Load Center And A Panelboard?"
(BTW, the "Question" was posed in a "Loaded Question" format - I.E. the Foreman already had an answer, but it did not match mine...).
The only thing I could think of was the Depth / Width dimensions of the Can (Enclosure).
Figuring I must have come close to a satisfactory answer, along with not being aware of the "Loaded Question" scenario (until my response was ... "De-Bunked"...), my jaw dropped rapidly to the floor upon the resultant corrections applied with the Foreman's rebuttal of:
"No!!! The Difference Is Load Centers Use Plug-On Breakers, And Panelboards Use Bolt-On Breakers".
Being the Glutten for punishment that I am, what do I do now???... of course - point out the "Semi-Obvious" information:
And the biggest "Clinchers" of them all:
- NEC has no definition or constraints towards the term Load Center, but the term Panelboard is vastly used,
- Most Catalogs describe Equipment of 225 Amps and less, at 250 VAC maximum; which reside within Metallic Enclosures having dimensions that allow for flush mounting in the typical 2" x 4" @ 14.5" finished Wall Cavity, as a Load Center, whereas Panelboards typically have 20" wide x 5.75" deep Enclosures,
[*] Most Load Centers may be ordered with either option for OCPD Terminal Mounting scheme: Bolt-On Bus or a Plug-On Bus,
[*] Square D Bus Kits are optional both ways - either use QO Plug-On Breakers, or remove the "Plug-On Stabs" from the Bussing and install QOB Bolt-On Breakers - commonplace for Panelboards and Load Centers.
Without going into full details, as to the reply from said Foreperson in rebuttal to the items above, let's just say I found out three things about myself which I did not know until that day:
[*] I know nothing about Electrical Systems, Systems Designs, Materials, Manufacturers Data, or anything related to the "Commonly Known Stuff That All Electricians Know",
[*] The fact that I was unaware of Panelboards vs. Load Centers means I will NEVER be any good as an Electrician - and impossible to even think of shooting towards being an Engineer,
[*] I am the least knowledgable Person in the Trade, have no NEC knowledge, never specified or even ordered Equipment, and I am the laughing stock on the job because of this.
This excitement took place exactly One Year and Two Months ago from this very Day, on a Public Works project which I was pulling a "Triple Threat" type working deal on
(Project Manager, Journeyman Installer, Revised installs FWO plans drawing / engineering / submission - shop drawings + record drawings... all at the same time).
Sorry to vent this here, and as you can see I still have issues over this.
Anyhow, AFAIK, the only difference between them is what you call them - Load Centers or Panelboards.
I prefer "Panelboards" and use the term as default to describe any OCPD assembledge cabinets that do not "Qualify To Be Defined As Switchgear", and contains MCCBs - but not Fuses or Fusible Switches.
As to the failures of Terminations (Plug-On vs. Bolt-On), I have seen a Hand-Full of failed Bolt-On scenarios - commonly from stripped threads on thin Aluminum Busses or other loose Terminations at the Bus.
On the other hand, have shot trouble + repaired many, many, many-many-many "Barbeque Scenarios" oriented around Plug-On Bussing issues, as applied to heavy, continuous Loads.
On this subject, I have a Red Wirenut which is fried, due to a poor makeup situation. Found it a few Months back during the Demolition part of a T.I. Project.
I'll post an image + story later in the Photos Forum.
P.S. Please excuse any spelling air-ors (errors).