--- title: "How an Access-Controlled Door Works | SPS Technical" url: https://sps-technical.com/services/access-control/how-it-works description: "The eight parts of an access-controlled door, fail safe vs fail secure in a fire or power cut, and choosing fobs, cards, phones, PINs or biometrics." lang: en-GB --- Image: Access control reader beside a commercial door (https://sps-technical.com/img/opt/7b4d82674_ChatGPTImageJun22202610_32_12PM3.webp) How a door works # How an Access-Controlled Door Works Every access-controlled door is made of the same few parts. Tap each one to see what it does, and what happens when the fire alarm sounds or the power goes off. Book a free access control survey: https://sps-technical.com/contact#type=survey Compare systems: https://sps-technical.com/services/access-control/installation Back to the access control hub: https://sps-technical.com/services/access-control Interactive door ## The eight parts of an access-controlled door Tap a number on the door, or a part in the list, to see what it does. Part 1 ### Reader Checks the fob, card, phone or PIN, and asks the controller whether this person may open this door now. 1. 1. Reader: Checks the fob, card, phone or PIN, and asks the controller whether this person may open this door now. 2. 2. Controller: Decides who can go where and when, and keeps a log of every door event, so you can see who opened which door. 3. 3. Lock: A magnetic lock or electric strike holds the door shut until a valid credential, exit button or fire alarm releases it. 4. 4. Exit button: Lets people out from the inside without a credential. 5. 5. Green break-glass: Cuts power to the lock in an emergency so the door can be opened at once. 6. 6. Door contact: Tells the system if the door is forced open or left open too long. 7. 7. Power supply and battery: Powers the lock and reader, with a battery to keep the door working for a time if the mains fails. 8. 8. Fire alarm link: Releases the door automatically when the fire alarm sounds, so nobody is trapped on an escape route. Fire and power ## Fail safe or fail secure? Every locked door is set to do one of two things when the power fails. We agree which for each door at survey. ### Fail safe (fail unlocked) Unlocks when the power fails or the fire alarm sounds. Used for: Escape routes and fire exits ### Fail secure (fail locked) Stays locked when the power fails, with a mechanical key override. Used for: Store rooms and cash offices, never an escape route Credentials ## Fob, card, phone, PIN or biometric? A credential is how a person proves who they are at the door: something they have, something they know or something they are. ### Fob or card Best for Most staff doors Watch out for Can be lent or lost, so remove leavers promptly ### Phone Best for Staff who always carry a phone, and remote sites Watch out for Needs the app set up on each phone ### PIN Best for Adding a second check to a fob Watch out for Codes get shared if used on their own ### Biometric Best for High-security rooms Watch out for Higher cost, and personal data rules apply FAQs ## Door and credential questions ### What happens to the doors in a fire or a power cut? Doors on escape routes are set to unlock (fail safe) when the fire alarm sounds or the power fails, so nobody is trapped. Doors that must stay locked, such as a store room, can be set to fail secure. We agree which is which at survey. ### Fobs, cards, PINs, phones or biometrics? It depends on the risk. Fobs and cards are the most common. Phones as credentials are convenient, and PINs or biometrics add a second check for higher-risk doors. ### What is the difference between Net2 and Paxton10? Net2 is managed from software on a PC or server and suits most single and multi-site businesses. Paxton10 is managed from a web browser and can include video in the same system. Both are licence-free. We help you choose at survey. ### How often should access control be maintained? At least once a year. We check every reader, lock and power supply, test the fire release, and review leavers and joiners so old fobs no longer work. ## Planning new doors? Book a free survey and we'll design the right access control for each door. Book a free site survey: https://sps-technical.com/contact#type=survey 01482 226570: +441482226570 Accreditations ## Why trust SPS Technical Independently certified, working to British Standards. Check every accreditation on the official register. ### SSAIB Registration HUMB018 Intruder alarms to PD 6662, CCTV to SSAIB Code of Practice SS2003, access control to SS2002, and fire alarm systems Verify at ssaib.org (https://www.ssaib.org/) ### BAFE SP203-1 Certificate 104302 · Organisation ID 303286 Fire alarm design, installation, commissioning and maintenance to BS 5839-1 Verify at bafe.org.uk (https://www.bafe.org.uk/) ### ISO 9001 and ISO 14001 1208-QMS-001 · 1208-EMS-001 Quality and environmental management, certified by Alcumus ISOQAR. ISO 9001 held since 1997 ### Safety and procurement CHAS-0004703 · Constructionline 92018 · SafeContractor PE5040 SSIP health and safety approval, procurement registration and Paxton Gold Installer status ### Police-response intruder alarms For intruder alarms, SPS Technical is an approved installer of police-response systems with the following forces, so your intruder alarm can be issued a police Unique Reference Number (URN) under the NPCC Police Requirements for Security Systems. - Humberside Police - Lincolnshire Police - North Yorkshire Police - South Yorkshire Police - West Yorkshire Police - Nottinghamshire Police - Derbyshire Constabulary - Greater Manchester Police Police approval applies to intruder alarms only. Since 1992 Established in Hull 1,750+ Systems maintained 2,850+ Scheduled service visits a year 4 Regional offices: Hull, Grimsby, Lincoln, Sheffield Trusted across universities, NHS and healthcare, local authorities, schools and academy trusts, logistics and industrial sites, transport, and stadiums and venues. Reviewed by the SPS Technical team · Last updated October 2026 Full accreditation details (https://sps-technical.com/about/accreditations-compliance) ## Structured data ```json [ [ { "@context": "https://schema.org", "@id": "https://sps-technical.com/#organization", "@type": "Organization", "name": "SPS Technical", "legalName": "SPS Security Ltd", "parentOrganization": { "@id": "https://sps-security.com/#organization" }, "description": "SPS Technical is the fire and security systems division of SPS Security Ltd, providing commercial fire alarm, CCTV, intruder alarm and access control design, installation, maintenance, monitoring and system takeovers across Yorkshire, Lincolnshire and the Humber.", "url": "https://sps-technical.com", "logo": "https://media.base44.com/images/public/6989f2350e53aab8836435e3/0ceea3d11_SPSTECHNICALLOGO.jpg", "telephone": "+441482226570", "email": "info@sps-technical.com", "foundingDate": "1992", "address": { "@type": "PostalAddress", "streetAddress": "Neptune House, Neptune Street", "addressLocality": "Hull", "addressRegion": "East Yorkshire", "postalCode": "HU3 2BP", "addressCountry": "GB" }, "hasCredential": [ { "@type": "EducationalOccupationalCredential", "name": "SSAIB registration HUMB018: intruder alarms (PD 6662), CCTV (SSAIB Code of Practice SS2003), access control (SSAIB Code of Practice SS2002) and fire alarm systems", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "SSAIB", "url": "https://www.ssaib.org" } }, { "@type": "EducationalOccupationalCredential", "name": "BAFE SP203-1 certificate 104302 (BAFE organisation ID 303286): fire detection and alarm system design, installation, commissioning and maintenance", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "BAFE", "url": "https://www.bafe.org.uk" } }, { "@type": "EducationalOccupationalCredential", "name": "ISO 9001:2015 certificate 1208-QMS-001", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "Alcumus ISOQAR" } }, { "@type": "EducationalOccupationalCredential", "name": "ISO 14001:2015 certificate 1208-EMS-001", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "Alcumus ISOQAR" } }, { "@type": "EducationalOccupationalCredential", "name": "CHAS membership CHAS-0004703", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "CHAS" } }, { "@type": "EducationalOccupationalCredential", "name": "Constructionline Bronze registration 92018", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "Constructionline" } }, { "@type": "EducationalOccupationalCredential", "name": "SafeContractor certificate PE5040", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "Alcumus SafeContractor" } }, { "@type": "EducationalOccupationalCredential", "name": "Paxton Gold Installer", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "Paxton" } }, { "@type": "EducationalOccupationalCredential", "name": "Approved installer of police-response intruder alarms: Humberside Police, Lincolnshire Police, North Yorkshire Police, South Yorkshire Police, West Yorkshire Police, Nottinghamshire Police, Derbyshire Constabulary, Greater Manchester Police", "credentialCategory": "certification", "recognizedBy": { "@type": "Organization", "name": "UK police forces (NPCC Police Requirements for Security Systems)" } } ], "areaServed": [ { "@type": "AdministrativeArea", "name": "East Yorkshire" }, { "@type": "AdministrativeArea", "name": "North Lincolnshire" }, { "@type": "AdministrativeArea", "name": "Lincolnshire" }, { "@type": "AdministrativeArea", "name": "South Yorkshire" }, { "@type": "AdministrativeArea", "name": "West Yorkshire" }, { "@type": "AdministrativeArea", "name": "North Yorkshire" } ], "knowsAbout": [ "Fire alarm systems", "CCTV systems", "Intruder alarm systems", "Access control systems", "System monitoring", "Planned preventative maintenance", "Fire and security system takeovers", "Multi-site fire and security maintenance", "Maintenance and compliance" ] }, { "@context": "https://schema.org", "@id": "https://sps-security.com/#organization", "@type": "Organization", "name": "SPS Security", "legalName": "SPS Security Limited", "url": "https://sps-security.com", "taxID": "02738677", "sameAs": [ "https://find-and-update.company-information.service.gov.uk/company/02738677" ], "parentOrganization": { "@type": "Organization", "@id": "https://spsgroupservices.com/#organization", "name": "SPS Group", "url": "https://spsgroupservices.com" }, "address": { "@type": "PostalAddress", "streetAddress": "Neptune House, Neptune Street", "addressLocality": "Hull", "addressRegion": "East Yorkshire", "postalCode": "HU3 2BP", "addressCountry": "GB" } }, { "@context": "https://schema.org", "@type": "Service", "@id": "https://sps-technical.com/services/access-control/how-it-works#service", "name": "Access control design", "description": "The eight parts of an access-controlled door, fail safe vs fail secure in a fire or power cut, and choosing fobs, cards, phones, PINs or biometrics.", "url": "https://sps-technical.com/services/access-control/how-it-works", "provider": { "@id": "https://sps-technical.com/#organization" }, "areaServed": [ { "@type": "AdministrativeArea", "name": "East Yorkshire" }, { "@type": "AdministrativeArea", "name": "North Lincolnshire" }, { "@type": "AdministrativeArea", "name": "Lincolnshire" }, { "@type": "AdministrativeArea", "name": "South Yorkshire" }, { "@type": "AdministrativeArea", "name": "West Yorkshire" }, { "@type": "AdministrativeArea", "name": "North Yorkshire" } ] }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://sps-technical.com/" }, { "@type": "ListItem", "position": 2, "name": "Services", "item": "https://sps-technical.com/services" }, { "@type": "ListItem", "position": 3, "name": "Access Control", "item": "https://sps-technical.com/services/access-control" }, { "@type": "ListItem", "position": 4, "name": "How It Works" } ] } ], { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What happens to the doors in a fire or a power cut?", "acceptedAnswer": { "@type": "Answer", "text": "Doors on escape routes are set to unlock (fail safe) when the fire alarm sounds or the power fails, so nobody is trapped. Doors that must stay locked, such as a store room, can be set to fail secure. We agree which is which at survey." } }, { "@type": "Question", "name": "Fobs, cards, PINs, phones or biometrics?", "acceptedAnswer": { "@type": "Answer", "text": "It depends on the risk. Fobs and cards are the most common. Phones as credentials are convenient, and PINs or biometrics add a second check for higher-risk doors." } }, { "@type": "Question", "name": "What is the difference between Net2 and Paxton10?", "acceptedAnswer": { "@type": "Answer", "text": "Net2 is managed from software on a PC or server and suits most single and multi-site businesses. Paxton10 is managed from a web browser and can include video in the same system. Both are licence-free. We help you choose at survey." } }, { "@type": "Question", "name": "How often should access control be maintained?", "acceptedAnswer": { "@type": "Answer", "text": "At least once a year. We check every reader, lock and power supply, test the fire release, and review leavers and joiners so old fobs no longer work." } } ] } ] ```