An electrician's skills learning and training is often talked about here as absolutely the key to developing a serious career within the industry. When a student begins their foundation training on an approved course like the City & Guilds Electrical NVQ 2330 level 2, it is soon realised that an important part of being able to reach the standard of first class workmanship, necessary to become qualified, is the quality of the tools an electrician uses.The purchase of your own set of high quality test instruments is probably one of the biggest investments an electrician will have to make when starting out in their new career. It would be a wise move to make! Precise measuring instruments enable the electrician to undertake a wide range of tests as well as help ensure that their installation work is 'sound' throughout the course of the job. In terms of good Health & Safety practice, instruments also help to keep an electrician and his client safe, alerting them to potentially dangerous situations and helping predict when a fault might occur in the future.As a student progresses through his training onto Electrical NVQ 2356 level 3 plus, undertaking the additional options in electrical PAT testing and 17th Edition Wiring Regulations 2382, for example, meter testing becomes a constant companion, needed to check and double check multiple circuits and connections.Generally, there are two types of test instruments :All-in-one/Multifunction testers - These are single units designed to carry out a wide range of tests, including continuity, insulation resistance, polarity, etc. The main benefits are cost savings (cheaper than purchasing individual meters for each test) and convenience (less equipment to carry around). On the downside, if the meter breaks you may not be able to carry out any of your tests. Cheaper meters may also exhibit the "jack of all trades, master of none" characteristic and should really be avoided.Single-application testers - These will generally be smaller than the three-in-one units and will be designed to carry out one specific function - RCD testing, earth fault loop impedance (Zs) testing, etc. Unlike three-in-one testers, they contain less electronics so unlikely to develop a fault. In the same way, your three-in-one meter will be needed every time you carry out any test, whereas your RCD tester will only be used when you're testing RCDs. On the downside, more meters means more investment - particularly relevant when it's time to get all the meters calibrated. Taking a professional approach means not cutting corners when purchasing tools.When buying any tester, make sure it's GS38 compliant, i.e. regularly checked, so as to conform with the requirements of BS 7617 (current edition) and HSE document GS 38. Always check in advance, before going on site, to make sure you know exactly how your tester works.