Connection Guide · Electrical

Square D Series A Bolt-on Conduit Hub Mount

A 4-hole flanged conduit hub mounting provision formed on electrical meter sockets and service equipment enclosures. It accepts Square D Series A bolt-on conduit hubs or closing plates (ACP/ACPA).

Illustration of a Square D Series A Bolt-on Conduit Hub Mount
Stands for
Series A = Square D conduit hub sizing/pattern designation A (typically for meter sockets)
Gender
female
Connects by
fastened, clamp, compression
Standards
UL 514B; NEMA 3R; ANSI C119; UL 67; ANSI C12.7; UL 50
Regions
North America, United States, Canada

How it connects

Secured via four #10-32 machine screws through corner holes into threaded enclosure embossments to clamp the flanged gasketed hub or plate against the enclosure top endwall.

Male and female halves

Female mounting surface with aperture and four tapped corner holes on the enclosure endwall; mates with a male flanged bolt-on conduit hub or closing plate.

Usually connects to

  • Square D Series A bolt-on conduit hubs (A075, A100, A125, A150, A200, A250); Square D Series A bolt-on conduit hub (A075, A100, A125, A150, A200, A250)
  • Adapter plates (such as A-L adapter AAP)
  • Square D ACP / ACPA blank closing plate
  • Type A-L conduit hub

Common sizes

  • Series A/Type A hubs span 3/4–2-1/2 in conduit trade sizes (A075–A250), including 1, 1-1/4, 1-1/2 and 2 in. ACP closes the same enclosure provision.
  • Reported mounting dimensions conflict: about 70 mm opening with a 63.5 mm (2.5 in) square pattern, or 76.2 mm (3 in) bore with 82.6 mm (3-1/4 in) square pattern. Confirm the exact enclosure drawing.
  • Hub conduit size does not imply a different enclosure opening for every size.

Where it is used

Residential/commercial power distribution and service entranceCSEDs and load centersOutdoor NEMA 3R enclosuresIndividual or horizontally ganged meter sockets

Variations

  • Series A standard four-bolt provision, with A100/A125/A150/A200/A250 hubs through 2.5 in conduit
  • Series A-L large-opening hub provision
  • Series B larger four-hole pattern, for up to 4 in conduit
  • ACP steel or ACPA aluminum closing plate

How to recognise it

Recognized by a raised boss with a central aperture (approx. 2.75" / 70 mm) surrounded by four tapped mounting holes arranged in a 2.5" (63.5 mm) square pattern on the enclosure top endwall.

Often confused with

Confused withHow to tell them apart
Square D Series B Bolt-On Conduit Hub MountSeries B hubs use a larger bolt spacing/pattern and cover up to 4-inch conduit, commonly used on main load centers, whereas Series A is smaller (up to 2-1/2") and typically found on meter sockets.
Square D Series B Bolt-On Conduit Hub OpeningSeries B hubs use a different 4-hole mounting pattern with offset/different spacing and flange dimensions compared to Series A.
Square D Series A-L hub provisionA-L is a separate larger mounting family. Schneider specifies AAP adapter plate to mount an A hub on an A-L opening; its closing plate is ACPL, not ACP.
Square D Series B hub provisionVerify the enclosure's specified hub series. B hubs are a separate family with B-CAP closing cap; a similar-looking bolt-on hub does not establish Type A compatibility.
Female conduit pipe threadThe enclosure provision receives a bolted flange. The conduit thread is in the removable hub, not inherent in this opening.

Also called

Square D Series A hub openingSeries A hub mounting patternClass 4110 Series A hub provisionSquare D Class 4805 Type A openingSquare D Series A hub provisionType A meter socket hub pattern

Good to know

Commonly specified on Square D and Schneider Electric outdoor NEMA 3R meter sockets and CSED enclosures to provide rainproof top conduit entry. Additional standard references: UL 414; UL 514A.

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