By Kent · Lock Depot Staff Writer

A Pair of Doors, One Magnet, and a Question About Knowing It Is Locked

A pair of glass doors on a tenant suite. The owner wants them held by a maglock and released from the reception desk. The installer prices a double-door magnet and moves on. Three weeks later the owner asks a fair question: how do I know the doors are actually locked when I leave at night? The plain magnet has no answer for that. It is either powered or not, and it says nothing about what the door is doing.

ASP Alarm Control sells two 600-pound double-door maglocks in the same dark bronze finish. The ASP-600DDURO is the plain one. The ASP-600DLBDURO adds a status LED, a bond sensor and a door status sensor. The lock is the same lock. The difference is the information.

What Both Magnets Share

Per the catalog listings, both carry 600 pounds of holding force and run on 12 or 24 volts DC, switch selectable. Current draw is low: 400 mA at 12 volts, 200 mA at 24 volts. Both list instant release with no hysteresis, meaning the door lets go the moment power drops, not a beat later. Both have built-in arc suppression, and non-aluminum parts are plated to resist corrosion.

Mounting is the same too: an E-Z mount system that needs no special tools, with self-drilling TEC screws. The magnet body is 19-3/4 inches long, 1-7/8 inches high and 1 inch wide. The armature is 7-1/4 inches long and 5/8 inch thick. The listing gives the armature height as 1-1/2 inches on both double-door models. Both can be used with any access control system.

What the Plain 600DDURO Gives You

Power in, door locked. Power out, door free. It is a clean, honest holding device, and for a tenant door that someone walks by all day, it is enough. The installer wires a supply, a release and an armature on each leaf, and the job is done. It is the right part when the only question is whether the door is held.

What the 600DLBDURO Adds

The DLB version puts three things on the same magnet. A bi-color status LED shows the lock's state at a glance. A bond sensor reports whether the armature is pulled tight to the magnet. A door status sensor reports whether the door is closed. The sensors carry SPDT relay contacts rated 3 amps, so they hand a clean dry signal to a panel or an indicator. Together, the listing says, the bond and door status sensors signal a powered and securely locked door.

That last phrase is the point. A magnet can be powered while the door hangs a half-inch open, a bent door or a stuck latch keeping the armature off the face. Powered is not secure. The bond sensor is what tells those two conditions apart, and the door status sensor is what tells you the leaf is really shut.

Where the Single-Door Model Fits In

If only one leaf needs holding, the ASP 600SDURO is the single-door version. Its magnet is 9-7/8 inches long, half the double-door body, with the same 600-pound rating and the same 12 or 24 volt selectable input. Do not stretch a single magnet across a pair. That is what the 19-3/4 inch double-door body is for.

Which One I Would Order

• A pair of interior doors, release from a desk, no alarm panel: 600DDURO.
• Any pair tied to an alarm panel, or where someone has to know the doors are truly locked: 600DLBDURO.
• A bank of pairs on one panel, where finding the one that failed matters: 600DLBDURO on every opening, so the panel can point to it.

Adding a sensor after the fact is a headache: wiring, mounting and a second product to find. If there is any chance you will want monitoring later, buying it on the magnet is simpler than retrofitting it. If you know you will never connect it to anything, buy the plain one.

Either way, put the magnet on a properly sized supply, and make sure the opening is allowed to be held by a magnet at all. A maglock on a door that is a required means of egress has to meet the local code for that opening. Check before you buy, not after the inspector shows up.

Install Notes From the Field

A magnet is only as strong as the contact between the face and the armature. Mount the magnet on the header and an armature on each leaf, then close the doors and check that each armature sits flat against the face, with no gap you can slide a card into. A twisted door or a worn hinge will show up as a leaf that does not seat, and that is a door problem, not a magnet problem. On the DLB, the bond sensor will tell you the same thing, which is a fair reason to buy it. Set the 12 or 24 volt switch to match the supply before you power up, and wire the sensor contacts to a panel or an indicator you will actually look at.

Common questions

What does a bond sensor do on a maglock?

It reports whether the armature is pulled tight against the magnet. On the ASP 600DLBDURO it works together with the door status sensor to signal a powered and securely locked door.

Do the two double-door models hold the same force?

Yes. Both are listed at 600 pounds of holding force, with the same 12 or 24 volt switch-selectable input and the same 400 mA at 12 volts draw.

What are the sensor contacts rated for?

The 600DLBDURO listing gives SPDT relay contacts at 3 amps for the sensors.

Can I use one single-door magnet on a pair of doors?

No. The single-door body is 9-7/8 inches long. The double-door body is 19-3/4 inches, made to span both leaves.

Do these magnets release instantly?

Both are listed as instant release with no hysteresis, and both include built-in arc suppression.

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See the full ASP Alarm Control line for maglocks, brackets and access hardware. For another pair-of-doors approach read RCI 8320: one maglock for a pair of outswinging doors, and see how a DynaLock monitor option handles the same status question.