How it connects
Secured using four fasteners (typically 1/4-20 or #10-32 machine screws) through a 4-hole square bolt pattern around a circular conduit cutout, compressing a raised lip or gasket to ensure a rain-tight NEMA 3R seal.
Male and female halves
Female (the enclosure cutout and threaded/clearance mounting hole pattern that accepts the male flange of the bolt-on RX hub)
Usually connects to
- Siemens Type RX bolt-on conduit hub
- Siemens RX closing plate / cover plate
Common sizes
- 4-bolt square pattern (~63 mm / ~2.5 in center-to-center bolt spacing) around a central ~54 mm (~2-1/8 in) cutout, accepting hubs sized from 3/4" up to 2-1/2" conduit trade size
Where it is used
residential electrical meter socketsmeter mainsoutdoor electrical service entrance equipment
Variations
- Siemens Type HD (large) hub opening
- Siemens Type HS hub opening
How to recognise it
Recognized on the top hub plate/roof of an outdoor meter socket or load center by four mounting screw holes arranged in a square pattern (~63 mm bolt square) centered around an approximate 54 mm knockout or hub opening.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Siemens HD conduit hub mounting flange | Type HD is the large hub series with a significantly larger bolt spacing pattern (typically 3" to 4" trade conduit sizes) compared to Type RX. |
| Square D Type A or B hub flange | Square D uses distinct bolt spacing patterns and hub flange geometries that are not directly interchangeable without adapter plates. |
Also called
Siemens Type RX hub openingSiemens RX hub flangeTalon RX conduit hub mount
Good to know
Siemens / Talon outdoor meter enclosures use Type RX interchangeable hubs for top service entrance conduit entries up to 2.5 inches. Larger sizes require Type HD or adapter plates.
Related connections
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