LCN SEM7840 Low-Profile Recess...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$563.00
$338.13

LCN SEM7840 Low-Profile Recessed Wall Mount Heavy Duty Door Holding Magnet - Powder Coat Finish

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Model: LCN-SEM7840
Selected Finish is

In Stock (leaves warehouse same day if ordered before 3pm ET)

$563.00
$338.13
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SEM 7800 Series Magnets

The Sentronic 7800 Series magnet releases when the fire alarm panel enters an alarm condition and the electrical current is interrupted, allowing the Door to perform manually until Power returns. The tri-voltage design provides 35 pounds of holding force. The magnet is fail-safe and will hold the Door until the current is interrupted. The SEM 7800 Series is protected by a 2-year warranty, meets ANSI/BHMA 156.15 and is UL Listed for metal smoke barrier or labeled fire doors. All magnets in the Series feature die-cast housings and are available in aluminum and dark bronze finishes. The SEM 7820 is floor-mounted, the SEM 7830 is surface wall-mounted, the SEM 7840 is low-profile recessed wall-mounted and the SEM 7850 is standard-profile recessed wall-mounted. All magnets but the SEM 7820 are suitable for pocket Door installation.

FEATURES

Body construction

  • Die cast housing
  • Choice of floor-mounted, recessed wall-mounted and Surface-Mounted wall magnets
  • Heavy-duty design

Quality and durability
  • Tri-voltage design provides 35 pounds of holding force
  • Magnets are fail-safe until the electrical current is interrupted
  • Performs manually under alarm conditions until Power returns

Installation
  • Wood and machine screw pack fasteners
  • Armature extensions available
  • SEM 7830, 7840 and 7850 can be used in pocket Door installations

Specifications
  • Tested and certified under ANSI/BHMA A156.15
  • UL listed for metal smoke barrier or labeled fire doors

Designs and Finishes
  • Available in aluminum and dark bronze finishes
  • Standard die-cast cover

Mounting/Arm Options The SEM 7800 Series can be floor-mounted (7820), surface wall-mounted (7830), low-profile recessed wall-mounted (7840), and standard profile recessed wall-mounted (7850). View the SEM 7800 catalog pages for mounting details and accessories.

Product Specs

Category:
Door Controls
Series:
SEM 7800 Series
ADA Compliant:
Yes
Mounting Detail:
Surface - Magnet
Warranty:
2 Year
BAA Qualified:
Yes
Subcategory:
Fire and Life Safety Closers
Mounting:
Wall Mount
Product Group:
Door Controls
Product Subgroup:
Electromagnetic Door Holder / Releases
Product Type:
Door Magnets
Projection:
6-3/4"
Door Type:
Interior Door
Finish Type:
Powder Coat
Commercial/Residential:
Commercial
Electronic:
Yes
Tags:
lcn sem7840, sem7840
Product Model:
SEM7840
Product Voltage:
12V/24V/120V

LCN LCN-SEM7840 – Frequently Asked Questions

1) What is the LCN SEM7840 low profile recessed wall mount door holding magnet used for?
This heavy-duty electromagnet holds open fire doors, commercial doors, and security doors. It releases automatically when fire alarm systems activate. Common in hospitals, schools, offices, and multi-story buildings where doors must stay open during normal use but close during emergencies.
2) What door types and weights is this magnet compatible with?
Works with steel doors, wood doors with steel plates, and aluminum doors. Check door weight capacity in manufacturer specifications. Verify door material contains ferrous metal for magnetic attraction. Non-ferrous doors require steel strike plates.
3) Does this work for left-hand and right-hand door installations?
This unit works for both left-hand and right-hand doors. The low profile design mounts flush in wall. Position determines door swing direction compatibility. Verify clearances and door travel path before installation.
4) What finish options are available for the SEM7840?
This model features powder coat finish for durability and corrosion resistance. Standard finish matches most commercial hardware. Powder coating provides long-lasting protection in high-traffic areas and various environmental conditions.
5) What electrical specifications does this door magnet require?
Verify voltage and amperage requirements in product documentation. Most commercial door magnets operate on 12V or 24V DC systems. Connect to fire alarm panel or access control system. Consult electrical specifications before wiring.
6) Are there building code requirements for electromagnetic door holders?
Yes. Fire code requires automatic release when fire alarm activates. Installation must comply with NFPA 80 and local fire codes. Some jurisdictions restrict use on certain door types. Check with local AHJ before installation.
7) What components are included with the SEM7840 package?
Package typically includes magnet assembly, mounting hardware, and installation instructions. Separate electrical connections and conduit may be required. Verify all components against packing list upon delivery.
8) How is this low profile magnet installed in the wall?
Requires recessed mounting in wall cavity. Cut opening per manufacturer template. Run electrical wiring to location before installation. Secure unit with provided fasteners. Test alignment and holding strength before final adjustment.
9) What maintenance does this electromagnetic door holder require?
Clean magnet face regularly to remove debris and metal particles. Test release function monthly with fire alarm system. Check mounting screws for tightness. Inspect wiring connections annually. Replace unit if holding strength decreases significantly.
10) What other LCN door control products work with this magnet?
Works with LCN door closers, exit devices, and access control systems. Compatible with most fire alarm panels that provide appropriate power output. Check our door hardware section for complete LCN product families.
11) Can this magnet be adjusted after installation?
Limited adjustment available after installation due to recessed mounting. Proper positioning during initial installation is critical. If major adjustments needed, may require reinstallation with new wall opening. Plan carefully using manufacturer templates.
How fast can I get the LCN LCN-SEM7840 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the LCN LCN-SEM7840 come with a warranty?
Absolutely. The LCN LCN-SEM7840 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the LCN LCN-SEM7840?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the LCN LCN-SEM7840 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.

Product Reviews

  • 5
    A Magnetic Solution: Keeping Doors in Place with Ease!

    Posted by Marshll on Apr 11th 2024

    This low-profile recessed wall-mount heavy-duty door holding magnet from Zensupply is a game-changer. One thing I love is its sleek design - blends right in! But, gotta mention, installation might need a bit of elbow grease. Overall, solid product!