Microwave Oven How legislation and environmental factors contribute to the cost of a Microwave oven By Paul Medland

Introduction Panasonic NN-A774S Microwave This Microwave has now been discontinued and has largely been replaced with the NN-A554W model This presentation highlights legislation and environmental factors that influenced the overall price of the Panasonic NN-A774S Microwave. This electronic product was for sale with Argos in 2004 at a price of £ per unit [Argos catalogue A/W]. It could also be found for sale with many other competitors such as Currys in the same price bracket. Panasonic NN-A554W

FCC The Federal Communications Commission, (FCC), have a number of strict laws affecting microwave ovens. Microwaves are electromagnetic waves with frequencies ranging from 0.3 GHz to 300 GHz, [Adams, S & Allday, J. Advanced Physics]. The FCC are responsible for the division of the EM spectrum, and have designated the frequency of 2.45 GHz to domestic microwave cooking, [FCC Bulletin 1999]. A microwave contains a magnetron which produces the microwaves used to cook / heat food. The magnetron passes these waves through a waveguide to govern the frequency of the microwave. It is very important that the magnetron and waveguide are built precisely, so that the ovens operation frequency is 2.45 GHz, to ensure that this law is not violated. Therefore the costs of these parts are higher, so the cost of the microwave is also higher for the consumer. The FDA also play an important role in microwave oven emission standards.

Leakage (FDA) The FDA, (Food and Drug Administration), have a microwave oven emission standard that permits leakage of 1 mW/cm 2 at the time of manufacture, and a maximum level of 5mW/cm 2 during the lifetime of the oven. These readings are taken 5 cm from the ovens surface, [FCC Bulletin 1999]. In order comply with this law, the cooking chamber of any microwave is a faraday cage. This is an enclosure made of conducting material / mesh, which in a microwave stops radiation from escaping the chamber, [esdjournal]. Any holes must be made smaller than the radiations wavelength. This undoubtedly means that there is a significant increase in the cost of the oven, (see next slide). Due to the small leakage of radiation from microwaves, they are known to interfere with equipment that operates in the 2.4… GHz region. This region is used for public communications, and poses problems for wireless networks, wireless surveillance, two way radios etc, [Ofcom, ISM bands].

Door Safety A microwave door allows you to see the ovens contents during operation, however due to the FDA leakage law, the door must seal the faraday cage. The door consists of a glass panel for viewing with a layer of conductive mesh to seal the cage. As, the wavelength of the microwave radiation is ≈ 12cm. The holes in the mesh are smaller than this value to stop microwave radiation from escaping through the door, whilst visible light with a much shorter wavelength can. The FDA also require oven doors to have two separate interlock systems to stop the microwave from radiating the moment the door is opened, [freepatentsonline]. The system in the Panasonic microwave consists of two microswitches, one connected to the microcontroller board, and the other to the high voltage magnetron transformer. The FCC and FDA regulations must be met for the microwave to be considered safe for consumer and industrial use. Obeying these three laws alone costs about £80 for this microwave. This figure includes the cost of the magnetron and waveguide ( £67.56 ), microswitches, faraday cage and meshed door.

Trigger mechanisms, activated by door locking pinsMicroswitches

≈ 1KV Magnetron transformer from the Panasonic NN-A774S Microwave

Magnetron Magnetrons are surrounded by a number of hazards which have to be protected against by manufacturers. Connections from Panasonic NN-A774S magnetron to high voltage transformer e.g. Microwave exposure and the high voltage power supply. Some magnetrons contain beryllium oxide which if ingested can be a very serious health hazard to humans and can cause cancers, [atsdr study, May 2008]. Therefore protective covering and door interlock systems are essential safety factors, which add to the cost of producing each microwave.

RoHS Compliance RoHS Compliance, (Restriction of Hazardous Substances). The EU Directive 2002/95/EC restricts the use of 6 substances in the manufacturing of electrical products. All of the electronic components and materials used to build an electronic product must not contain any more than the below concentrations of the 6 listed substances to be RoHS compliant. A list of RoHS compliance certificates for each component should be kept by the manufacturer, [rapid electronics online]. Restricted SubstanceMax Concentration Cadmium0.01% Lead0.1% Mercury0.1% Hexavalent Chromium0.1% PBB (Polybrominated Biphenyls) 0.1% PBDE (Polybrominated Diphenyl Ethers) 0.1% This legislation means that the cost of producing each microwave is higher, as this law must be followed closely. Panasonic make sure that they select and use only RoHS compliant components and materials, (including lead free solder), also meaning that records must be kept. Component prices can also be higher, so bulk buying is essential to reduce costs.

BEAB The British Electrotechnical Approvals Board, (BEAB), mark, is a UK safety mark, used by electrical / electronic manufacturers to support CE marking, and to provide evidence of product safety if claims are made against the manufacturer, [BEAB]. A BEAB Approved mark on a product is not compulsory, but shows that a 3rd party has verified its safety, and that the product has met all of the relevant standards. This investment shows the extra efforts that have been made by the manufacturer to ensure that the product is safe, and thus widens market access, [Intertek]. BEAB approval may be used to obtain other international certificates under the CB and ENEC schemes, [BEAB]. The Panasonic NN-A774S microwave bears the BEAB Approved mark, which shows that this extra investment has been made in product safety. Along with CE marking, the cost of the microwave will be higher to the consumer, however mass production spreads the cost of this investment, which minimizes the overall price increase. ( One certificate covers all microwaves of that model number produced).

CE Mark A CE mark on a product is a declaration by the manufacturer that the product meets all the appropriate requirements of the EC directives. These directives were created to ensure safety and quality of products throughout the EC members. (European Community), [Investni]. A CE mark on a product means that it can be marketed freely throughout the EC, as the mark shows the products conformity with the directives. CE marking provides easier access for the product in the European market, mainly as distributors usually require CE certification before taking on the product. Certification may be requested by customs, competitors, or in the case of a claim against the product, [Caliso]. The Panasonic NN-A774S microwave bears the CE mark visibly on the outside. Internally, many of the other parts visibly bear the CE mark, including the magnetron, control unit and high voltage PSU. This means that there have been multiple investments in the CE mark for different parts, mostly due to the integration of other manufacturers. Therefore there is a significant cost involved in making sure that this product is CE certified, so the cost of each oven will be higher for the consumer as a result.

WEEE Both RoHS and WEEE (UK Waste Electrical and Electronic Equipment), aim to improve the environment and reduce the amount of landfill waste. WEEE came into force on the 2nd Janurary It is a new piece of legislation which places the responsibility of the environmental management of WEEE on the producers, brand owners, importers, distributors and retailers of EEE, [Rapid online]. All producers, regardless of their size must be registered with a compliance scheme, and supply the weights of the products that they put on the market. An example of a scheme is WeeeCare, which has its own national collection programme / vehicles, and has been handling, recycling + treating WEEE for over 20 years, [Rapid online]. Instead of dumping WEEE into landfills, producers now have the responsibility of financing the collection, treatment, recovery, reuse, recycling, and the afterlife disposal of the WEEE that they are committed to, [Rapid online]. This legislation bears heavy costs for producers of EEE, so product prices are marginally higher as a result. This includes all EEE produced by Panasonic.

Summary FactorHow Cost of Product is Affected FCC – Operation frequencyHigher, due to precisely built magnetron and waveguide. FDA – Radiation leakage, (protective covering, door interlock systems and mesh). Much higher, as cooking chamber and magnetron must be surrounded by a faraday cage. FCC + FDA laws add at least £80. RoHS complianceHigher, as all components and materials used must obey RoHS, and records must be kept. BEAB markSlightly higher CE markHigher. Many internal components have their own CE mark, so multiple certificates have been obtained. WEEEHigher, as investment in the products afterlife treatment is required.

References Adams, S & Allday, J, Advanced Physics, Oxford, Pg 241 (EM Spectrum-Microwaves) Argos Catalogue Autumn / Winter 2004 (Panasonic NN-A774S microwave retail price) (May 23 rd 2008, Beryllium Toxicity, K.G, MD, MPH) (Summer 2000, BEAB) (CE marking and certification, CALISO) (EIA and ESD Association, Faraday Cage) ( FCC OET Bulletin 56, 4 th edition, August 1999) (DE, US patent no: , 1978, Interlock Switch system)

References (2) (Rapid Electronics, 2002 / 95 / EC, RoHS/WEEE) (Invest Northern Ireland, January 2007, CE Marking Programme) (P.Hansell, 2.4GHz ISM band) (6 th June 2007, Intertek BEAB certification services) page/cust_portal/ITK_PGR/ABOUT_INTERTEK_ETL_PG/GLOBAL_CERTS_MARKS_PG/BEAB%20Mark Any Questions?