Rules of the certification inspection
The UL inspector's inspection basically belongs to the mechanical work. According to the different products, The inspector's inspection is based on Bulletin, Procedure, FUII (if any, included in the rules) and UL standards (if required in FUII). If the inspector visits the factory, the factory is producing the UL products or the UL products in stock, so the inspector will take samples in one of the following ways:
1.         Each component is extracted from the production line, and also adds with a complete product extracted from the warehouse.
2.         Extract components is extracted from the warehouse plus complete products on the production line.
3.         Extract the complete product from the warehouse for splitting.
 
The exact number of samples is determined by Procedure, FUII, SAP or a direct order from the UL lab. The inspector does not always to inspect all products during each inspection, but they will try to test all product categories or models within a year or at least two years.
 
Generally speaking, UL is not too demanding for the factory production system, only to require the measurement of the instrument and equipment once a year, keep a good record of the factory's own inspection, and have a certain control over nonconforming products. During the inspections, Site Representatives (UL inspectors) will focus their attention on the product itself; they will check the product structure, components and assembly according to the above inspection.
 
For the parts that involve the product safety, the general rules will specify requirements for UL certified products, and will indicate the manufacturer and model; for some injection molded parts such as housings, shields, etc., In general, the fine will specify the requirements for its raw material and size. The on-site representative will check the UL mark as specified in the above and the detailed rules.
 
In addition, if the Procedure or FUII or standards require the on-site testing of the product, the site representative will ask the factory inspector to do the corresponding tests, while the on-site representative will witness it. If the Procedure requires that samples should be sent to UL for tracking test, the factory shall cooperate with the inspector to make the corresponding samples, after the inspector has written the sample labels, the address will be supplied and sealed the sample then sent by the factory to the corresponding UL laboratory. If the factory produced the products fully comply with UL relevant inspection standards, and there are no other violations of tracking service agreement, the inspector will issue the inspection report; the representative of the factory shall sign the report when it is confirmed and the content is correct, so a test will be completed. If the inspection process does not conform to the inspection standards, the examiner will issue a Variation Notice, and according to specific circumstances to take appropriate measures. For an unauthorized product using the UL mark, the inspector will ask for removal of the UL mark; For the products that do not meet UL requirements, the inspector will ask the factory to remove the UL mark or rework to meet the requirements. If the factory does not agree with the above treatment, you may temporarily retain the UL mark, but the shipment must be stopped and the inspector will notify the appropriate laboratory of this situation, and let UL to determine whether the UL tag can be retained or not; if there are only some small problems, do not affect the safety of the product, the inspector will make a provisional acceptance decision and report to the relevant laboratory; If there are some obvious standard errors, such as typing errors or unit errors, which does not affect the quality of factory products, but as the documentation of the UL, the examiner will issue a change notice. In general, unless it is the responsibility of the UL Company, the inspector will ask the factory to explain the non conformity to the appropriate laboratory, and UL will respond accordingly to your explanation. Of course, the inspector's judgment is only temporary, and the final decision is certainly in UL labs. Of course, the inspector's judgment is only temporary, and the final decision is certainly in UL labs. If the factory does not agree with the method of inspection, it can be reflected to the corresponding laboratory, at this time, the inspector has the obligation to provide the corresponding contact and contact method. After confirming the contents of the notice of change, the factory representative should sign the notice.
 
The frequency of tracking detection
UL is clearly defined the frequency of tracking inspection.
The R class services under normal circumstances. For most R class factories, the inspector’s access frequency is four times a year, but it does not rule out the possibility of two times in the first quarter, and the total shall not exceed four times unless special instructions are given. If the product does not conform to the UL requirements and needs to be reworked during the inspection, the UL inspector will have an additional inspection to confirm that the shipment has been reworked and meets the requirements of the UL.
 
For the On-Call services, it should be at least once a year.
QMFZ2，QMFZ3-Plastics, once a quarter until the tracking test samples are required for all UL laboratories. WPYR2-Special-Use Switches, see the table below: the UL quarterly maximum inspection times for quarterly production.
0-25,0001
25,000-100,0002
100,000-250,0003
250,000-500,0004
500,000-750,0006
750,000-1,000,00010
1,000,000-1,250,00011
1,250,000-2,500,00012
2,500,000-20
 
There are many products with only the least number of inspections, such as labels, printed materials and other products, they only required once a year, at most not more than two times a year.
The services of L class
For the class L factories, the frequency of inspection depends on the amount of use of the UL tag (usually proportional to the output of the product) and the complexity of the product. UL specifies the quantity of the product that requires a test; it also specifies the maximum number of inspections per quarter.
 
If the lamp was tested one in every 3200, the upper limit is 18 times per quarter, In other words，even if the factory produced more than 3200 x 18=57600 products in the quarter, the number of tests is still 18 times. For your product, you can contact the UL site responsible for your factory or contact us. To obtain the quantity required for a test.
 
Special inspection service (SPI)
 
If you break the tracking test agreement signed with UL, you may be severely penalized by UL,
Including special inspection of your factory
 
The factory review of UL certified
Before the first shipment, the UL certification products will be check by the factory which have the UL provincial import and Export Commodity Inspection Bureau (CCIB) authorized by the local authority. And track checks every year.
 
The service agreement of trace inspection
The "tracking inspection service agreement" guide is designed to assist UL clients in understanding the establishment and implementation of tracking inspection services. Often, UL's "tracking inspection service agreement" is not taken out of reference because it is a legal document that is placed inside the filing cabinet. This guide is not stored in the archives cabinet, but was placed on the convenience that can refer in the future. The guide is written in plain and non legal terms, its purpose is to answer the questions often asked by UL customers.
 
UL's trace inspection service protocol specifies the legal relationship between a complete UL and your company. Therefore, the information provided by this guide shall not in any case to be used as a substitute for or change of the provisions in the tracking inspection service agreement. Also, what you should notice is that: this guide does not include every question that UL customers might ask. Some provisions of "tracking inspection service consents" are referred to in this guide for the convenience of your reference to the agreement.
 
The fee standard of UL
The UL charge for its services, which Is depends on the nature and scope of the required inspection service. The amount of the service charge is charged at the current rate. This rate can be changed sometimes, the notice of change will be sent to the applicant in writing. The fees charged to any additional tracking inspection service are also to be charged to the applicant. The additional track inspection service is considered to be the time which required:
1.       When the manufacturer do not meet the requirements of the UL, additional inspection time is required;
2.       When the control of the manufacturer in the normal condition is insufficient. All the invoices must be paid within 30 days after the disclosure. If the fees are not paid during this period, your company will be deemed to have failed to fulfill its obligations. (paragraph twenty-second)