{"product_id":"dh-58-rolling-door-magnetic-contact-nc-metal-door-sensor","title":"DH-58 Rolling Door Magnetic Contact – NC Metal Door Sensor","description":"\u003ch2 data-section-id=\"5ptua8\" data-start=\"112\" data-end=\"129\"\u003eKey Features\u003c\/h2\u003e\r\\n\u003cp data-start=\"131\" data-end=\"358\"\u003e• Heavy-Duty Metal Housing Design\u003cbr data-start=\"164\" data-end=\"167\"\u003e• Normally Closed (NC) Magnetic Contact\u003cbr data-start=\"206\" data-end=\"209\"\u003e• Long Detection Gap for Rolling Doors\u003cbr data-start=\"247\" data-end=\"250\"\u003e• Durable Zinc Alloy Body\u003cbr data-start=\"275\" data-end=\"278\"\u003e• Surface Mount Easy Installation\u003cbr data-start=\"311\" data-end=\"314\"\u003e• Compatible with Alarm \u0026amp; Security Systems\u003c\/p\u003e\r\\n\r\\n\u003ch2 data-section-id=\"4mujha\" data-start=\"365\" data-end=\"390\"\u003e\u003c\/h2\u003e\n\n\u003cp data-start=\"392\" data-end=\"556\"\u003eThe \u003cstrong data-start=\"396\" data-end=\"440\"\u003eDH-58 Rolling Door Magnetic Contact (NC)\u003c\/strong\u003e is a heavy-duty security sensor designed specifically for \u003cstrong data-start=\"499\" data-end=\"555\"\u003erolling shutters, garage doors, and industrial gates\u003c\/strong\u003e.\u003c\/p\u003e\r\\n\u003cp data-start=\"558\" data-end=\"785\"\u003eUnlike standard door contacts, this model features a \u003cstrong data-start=\"611\" data-end=\"660\"\u003estrong metal housing and larger detection gap\u003c\/strong\u003e, making it ideal for environments where larger door movement occurs, such as warehouses, factories, and commercial shutters.\u003c\/p\u003e\r\\n\u003cp data-start=\"787\" data-end=\"1022\"\u003eThe sensor operates using a \u003cstrong data-start=\"815\" data-end=\"855\"\u003emagnetic reed switch and magnet pair\u003c\/strong\u003e. When the door is closed, the magnet keeps the circuit closed. When the door opens and the magnet moves away, the circuit opens and sends a signal to the alarm panel.\u003c\/p\u003e\r\\n\u003cp data-start=\"1024\" data-end=\"1214\"\u003eThe \u003cstrong data-start=\"1028\" data-end=\"1055\"\u003ezinc alloy metal casing\u003c\/strong\u003e provides durability and resistance against harsh environments, making it suitable for industrial security installations.\u003c\/p\u003e\r\\n\r\\n\u003c!--zzmv2--\u003e\r\\n\u003cp\u003e\u003cstrong\u003eBuilt for rolling shutters and metal doors.\u003c\/strong\u003e The DH-58 is a heavy duty magnetic contact designed for the doors that defeat ordinary sensors: steel rolling shutters, roll up godown doors, metal gates, and warehouse entrances. Standard plastic door contacts fail on these because the gap is wide, the door moves and vibrates, and surrounding steel interferes with the magnetic field. This unit is built specifically for that job.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eWhy shutters need a different sensor.\u003c\/strong\u003e A rolling shutter does not close with the precision of a hinged door. It settles differently each time, sits with a wider and less consistent gap, and rattles in wind. A sensor designed for a wooden office door will report false openings or miss real ones. A shutter contact tolerates a wider operating gap and is housed to survive being knocked, which is why it stays reliable on a shop front that opens and closes twice a day, every day.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eWhere it is normally used.\u003c\/strong\u003e Shop shutters on main roads, warehouse and godown roller doors, factory gates, garage doors, and any steel door where a normal contact has already failed. In Pakistan the most common installation is a shop shutter wired to an alarm panel so the owner is alerted if the shutter is lifted after closing.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eNC contact and why it matters for security.\u003c\/strong\u003e The DH-58 is a normally closed contact, which is what alarm systems expect. In an NC circuit, current flows continuously while the shutter is shut. Opening the shutter breaks the circuit and triggers the alarm. Critically, so does cutting the cable, which means tampering with the wiring sets the alarm off rather than silently disabling it. A normally open contact does not offer this protection, and it is the reason NC is standard for security applications.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eMounting on steel without losing reliability.\u003c\/strong\u003e Metal is the enemy of magnetic sensing, so mount the contact so the magnet and sensor face each other directly rather than at an angle. Where reliability is marginal, fit both halves on thin non-metallic spacers to lift them slightly off the steel surface. Position the pair away from the shutter guide rails where movement is greatest, and check alignment again after a few weeks of use once the shutter has settled.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eGetting the gap right.\u003c\/strong\u003e Every magnetic contact has a rated operating gap. A shutter that sits loosely may exceed it, producing an alarm that triggers every time the wind moves the door. If your shutter has significant play, tell us before ordering and we will confirm whether this model’s gap tolerance suits your installation or whether you need a wider gap unit.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eCabling on a moving door.\u003c\/strong\u003e The cable must run to the fixed frame side, never to the moving shutter. Route it in conduit and leave no exposed run, because an accessible sensor cable on a shop front is the first thing an intruder will cut. On a shutter that is opened daily, secure the cable properly so repeated vibration does not eventually work a connection loose.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eConnecting it to your alarm.\u003c\/strong\u003e Wire the contact into a zone on your burglar alarm panel so a shutter opening triggers the same siren and notification as any other zone. Where you want a phone alert rather than a siren, it can also feed a dialler or a smart relay module. ZZ Marts stocks the panels, sirens, diallers, and cabling to complete the installation.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003ePower and load shedding.\u003c\/strong\u003e Wired contacts draw their power from the alarm panel and need no batteries of their own, so they keep working as long as the panel does. Fit a backup battery at the panel and your shutter stays monitored through load shedding, which is exactly when an unmonitored shutter is most exposed.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eWired rather than wireless, and why that is right here.\u003c\/strong\u003e For a shop shutter, a wired contact is the better choice. It never needs a battery change, does not depend on WiFi or internet, and cannot be defeated by jamming or a router being switched off. Wireless sensors suit interior doors and rented spaces; a commercial shutter protecting stock deserves a wired connection to a proper panel.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eWill it work on my shutter?\u003c\/strong\u003e Send us a photograph of the shutter and the gap when closed on WhatsApp and we will confirm before you order.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eCan it be used on a normal door?\u003c\/strong\u003e Yes, though for a standard wooden or aluminium door a smaller recessed or surface mount contact is usually neater and less expensive.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eDoes it need its own power supply?\u003c\/strong\u003e No. It draws power from the alarm panel it connects to.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eHow many do I need for a wide shutter?\u003c\/strong\u003e One contact per shutter is normal. Very wide shutters that lift unevenly sometimes justify two, which we can advise on.\u003c\/p\u003e\r\\n\u003cp\u003e\u003cstrong\u003eBuying from ZZ Marts.\u003c\/strong\u003e Available at our Karachi (Saddar) and Lahore stores with delivery across Pakistan, supplied by Zam Zam Traders, trading in security hardware since 2005. We also stock recessed and surface mount door contacts for standard doors, wireless Tuya door sensors, alarm panels, sirens, and cabling. Tell us your shutter type and what you are connecting to and we will specify the whole job rather than just the sensor.\u003c\/p\u003e","brand":"ZZ Marts","offers":[{"title":"Default Title","offer_id":52827975778616,"sku":"DH-58","price":1199.0,"currency_code":"PKR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1012\/3932\/4984\/files\/Metallic-magnetic-door-sensors-by-ZZ-Marts.png?v=1787211284","url":"https:\/\/zzmarts.com\/products\/dh-58-rolling-door-magnetic-contact-nc-metal-door-sensor","provider":"ZZ Marts | Zam Zam Traders","version":"1.0","type":"link"}