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Quick Verdict

Choose the mount by what is behind the door at full open. A solid, reinforced wall with a box in it takes a concealed wall unit: LCN SEM7840 or SEM7850 recessed, or Rixson 998M (3-5/8 in. projection, about $485 at NLS). A wall you cannot open takes a surface unit: LCN SEM7830, Sargent 1560 or Rixson 996M. No wall within reach of the door takes a floor unit: LCN SEM7820 or Rixson 980M. LCN SEM 7800 and Sargent 1560/1561 units hold 35 lbs and are fail safe, so the door releases on alarm or power loss and the closer shuts it. The closer is mandatory. On labeled fire and smoke doors, the authority having jurisdiction (AHJ) and NFPA 80 govern hold-open approval and release wiring.

How does a fire-alarm-released door holder work?

An electromagnetic door holder is a wall or floor magnet plus a steel armature on the door. While the magnet is energized, it holds the door open against the closer. When the fire alarm panel (or a local smoke detector) drops power, the magnet releases and the door closer swings the door shut and latches it. LCN's listing describes the SEM 7800 Series as "fail safe and hold until the current is interrupted," and Sargent's 1560 listing says the same: "When electrical power fails, doors will release to close automatically."

That fail-safe behavior is the whole point. NFPA 80 requires a fire door held open to close automatically on alarm; a hook, kick-down stop or hold-open closer arm that a person has to release does not do that on a labeled door. Mechanical hold-opens belong on non-rated doors; see our overhead door stops and holders guide for that hardware. Holders are listed to ANSI/BHMA A156.15 (LCN, Rixson and Sargent all cite it), and LCN notes every SEM Series magnet is UL listed for smoke barrier or labeled fire doors.

Release wiring ties into the fire alarm system, so it is work for a qualified technician coordinating with the fire alarm contractor, and the AHJ has the final word on which doors may be held open and how they release. Held-open fire doors are also checked during the annual inspection covered in our NFPA 80 annual fire door inspection post.

What to order: a listed electromagnetic holder from door stops and holders, sized to the wall or floor condition below.

Surface, recessed wall or floor mount: which fits the opening?

Site condition	Mount type	Reason
Door opens against a stud or masonry wall with a recessed box possible	Recessed (flush) wall	Concealed wiring, lowest projection into the corridor
Finished wall you cannot cut, or wiring run in surface raceway	Surface wall	Mounts on the face; Rixson 996M lists surface wiring
Door opens against a wall farther than the armature can reach	Wall unit with extension or spacer	Armature extensions (LCN) or 900 base spacers (Rixson) close the gap
No wall behind the door at full open	Floor	Conduit feeds the floor plate directly (Rixson 980M)
Tight corridor, projection matters for traffic	Low projection wall	Rixson 990M at 1-13/16 in. or 989 at 7/16 in.
Solid wood door, armature alignment issues	Adjustable armature wall	Rixson 994M is recommended for solid wood doors
Pocket door installation	LCN recessed or surface wall	SEM7830, SEM7840 and SEM7850 are listed as suitable for pocket doors

Wall units need structure. Rixson states it on every wall model: the wall "must be properly reinforced and outlet box adequately fastened." Unbacked drywall pulls out on the first kick. Floor units (6-5/8 in. of floor space for the 980M) are a trip hazard; use them only when no wall is in reach.

What to order: the recessed LCN SEM7850 for most new walls, the floor LCN SEM7820 where there is no wall.

Which models are available: LCN SEM7800, Rixson 990 series or Sargent 1560?

Model	Mount	Armature / extension	Voltage (as listed)	Link
LCN SEM7850	Recessed wall	Standard profile armature; LCN extensions available	Tri-voltage 12V, 24V, 120V	SEM7850
LCN SEM7840	Recessed wall	Low profile armature	Tri-voltage 12V, 24V, 120V	SEM7840
LCN SEM7830	Surface wall	Low profile armature	Tri-voltage 12V, 24V, 120V	Same family
LCN SEM7820	Floor	Low profile armature(s)	Tri-voltage 12V, 24V, 120V	SEM7820
Rixson 998M	Wall, concealed wiring	3-5/8 in. total projection	See Rixson cut sheet	Rixson 998M
Rixson 980M	Floor, single door	6-5/8 in. floor space	See Rixson cut sheet	Same family
Rixson 996M	Wall, surface wiring	Adjustable armature, 4-1/8 in. projection	See Rixson cut sheet	Same family
Sargent 1560	Surface wall	1 in. extension 52-2573 included, 2-5/8 in. projection	120 VAC, 24 VAC/DC, 12 VDC	Sargent 1560
Sargent 1561	Flush wall	Same 1 in. extension included	120 VAC, 24 VAC/DC, 12 VDC	Same family

LCN SEM 7800. Tri-voltage, 35 lbs of holding force, die cast housing, shipped with cover, armature and WMS screw pack, non-handed, for timber or metal doors. Finishes are aluminum (689) and dark bronze (695) only. The SEM7850 is about $443 at NLS; the SEM7840, SEM7830 and SEM7850 share that price, while the floor SEM7820 runs about $783. The 7850 vs 7840 difference is the armature: standard profile on the 7850, low profile on the 7840.

Rixson. All Rixson units listed here meet ANSI/BHMA A156.15 Grade 1. Projection is the main selector: 989 at 7/16 in., 990M at 1-13/16 in., 998M at 3-5/8 in., 994M at 3-3/4 in., 996M at 4-1/8 in. and 999M at 4-3/8 in. Box requirements differ: the 998M needs a 2 x 4 x 1-3/4 in. outlet box, the 990M and 994M a 2 x 4 x 2-1/2 in. box, and the 999M mounts on a 2 x 4 in., 4 in. square or 4 in. octagonal box. Finishes include 689 aluminum painted and 696 gold painted, with 690 dark bronze on the 998M and 999M.

Sargent 1560/1561. Current draw is listed as 0.020 A at 120 VAC or 24 VAC/DC and 0.040 A at 12 VDC, with 35 lbs typical holding force. Sargent recommends mounting on the top rail of the door within 6 in. of the lock stile edge, and the units fit a standard outlet box.

What to order: Rixson 998M when the wall has a 2 x 4 box and you want concealed wiring; LCN SEM7840 when you want low profile armature in a recessed wall.

Which voltage and armature options should you specify?

Voltage follows the release circuit, not the holder. Ask the fire alarm contractor which voltage the release relay switches, then confirm the holder accepts it. LCN SEM 7800 units are tri-voltage, so one SKU covers 12, 24 or 120 V. Sargent 1560/1561 list 120 VAC, 24 VAC/DC and 12 VDC. For Rixson, take the voltage from the Rixson cut sheet for the exact model before ordering.

Armature reach is the second variable. If the door's open position leaves a gap to the wall, add an extension rather than moving the magnet:

• LCN: armature extensions available from LCN for the SEM 7800 Series.
• Sargent: a 1 in. extension (p/n 52-2573) ships standard and raises armature projection to 2-5/8 in.
• Rixson: the 900-700 is a 7 in. spacer and the 900-Z a 90 degree bend spacer; both must be used with the 900 base, and the 900-Z with its 900 base extends the armature 3 in. beyond the contact plate. Replacement armatures (997510M) fit the 980M, 981M, 990M, 991M, 996M and 997M; the 998315M wall cover fits the 994M, 997M, 996M and 998M.

What to order: the holder plus the extension or spacer measured from the door face at full open to the wall, from door stops and holders.

Why must the closer stay, and how do the two coordinate?

The holder only holds. The closer is what closes and latches the door when the magnet drops, which is why LCN states that "a manual door closer is used to control and close the door" and Sargent designs the 1560 "for use with self-closing fire and smoke barrier doors." Three coordination checks:

1. Opening angle. The holder sets where the door parks; the closer arm and any overhead stop must allow that angle.
2. Closer power. Thirty-five pounds of holding force has to beat the closer's spring at the hold position, and the closer must still latch the door from that angle on release. A closer adjusted too strong pulls doors off the magnet; too weak and the door stops short of latching.
3. No hold-open arm on rated doors. If the closer has a mechanical hold-open arm, it defeats automatic release. Closer arm options are covered in door closer arm types and mounting options.

If the door drifts off the magnet or slams on release, check the closer before blaming the holder. A closer losing fluid will not control the door from a held-open position; our sibling guide on a door closer leaking oil and what to order covers that fix.

What to order: the holder that matches the closer's hold position, mounted where the LCN SEM7850 or equivalent armature lands flat at full open.

What goes on the door holder order sheet?

• Mount: recessed wall, surface wall or floor.
• Wall condition: stud, masonry, reinforcement, box size (2 x 4 x 1-3/4 in., 2 x 4 x 2-1/2 in., 4 in. square or octagonal).
• Projection needed from wall to door face at the hold position.
• Release voltage from the fire alarm contractor.
• Armature: standard or low profile; extension or spacer.
• Finish: 689 aluminum, 695 or 690 dark bronze, 696 gold, EN sprayed aluminum.
• Rating: smoke barrier or labeled fire door; AHJ approval of the hold-open.

What to order: everything above in one cart from door stops and holders.

Common mistakes

1. Mounting a wall magnet in unreinforced drywall.
2. Ordering the holder before confirming the release voltage with the fire alarm contractor.
3. Removing or disabling the closer because "the magnet holds the door now."
4. Leaving a hold-open closer arm on a labeled fire door that also has a magnetic holder.
5. Ordering a floor unit where a wall unit with an extension would reach.
6. Mixing up SEM7850 (standard profile armature) and SEM7840 (low profile armature).
7. Ignoring the box depth: the 990M needs 2-1/2 in., the 998M 1-3/4 in.

FAQ

How does an electromagnetic door holder work with the fire alarm? The holder stays energized and holds the door open; when the fire alarm or a smoke detector cuts power, the magnet releases and the closer shuts the door. LCN SEM 7800 and Sargent 1560 units are fail safe, so a power loss also releases the door. The AHJ decides which doors may be held open.

What is the LCN SEM7850? The SEM7850 is a recessed wall magnetic door holder with a standard profile armature, tri-voltage (12, 24 or 120 V) and 35 lbs of holding force. It is UL listed for smoke barrier or labeled fire doors and comes in aluminum or dark bronze.

What is the Rixson 998M? The Rixson 998M is a wall-mounted electromagnetic door holder/release with concealed wiring and a 3-5/8 in. total projection. It mounts on a 2 x 4 x 1-3/4 in. outlet box in a reinforced wall and meets ANSI/BHMA A156.15 Grade 1.

Magnetic door holder wall mount vs floor mount: which is better? Wall mount whenever the door opens to within reach of a wall, because it keeps the floor clear and wires through a standard box. Floor mount (LCN SEM7820, Rixson 980M) is for doors with no wall behind them at full open. Note that searches for the HES 9800 land here, but that part is an electric strike for Adams Rite rim devices, not a door holder.

Next step

Shop door stops and holders, or order the LCN SEM7840, Rixson 998M or Sargent 1560 directly. Orders by 3 p.m. ET ship the same day; ground shipping is free from $450. Send corridor-wide holder schedules to the quote desk, and agencies can use government PO intake.