17th
Edition Installation Testers
Trip-lock
A method of performing a loop test on RCD protected circuits without tripping the RCD. All Metrel mul- tifunctional testers have the non trip facility. The TripLock function is ZLoop (RCD) MI 3000 tester, Z(s) RCD testing MI 3100, MI 3002, MI 3102; Z-loop (protection: RCD) MI 3101, MI 3105.
Tip commander
An electronic remote to help make continuity, insulation testing easier by placing the test button and either memory or backlight button in the hand of the electrician. Available as a 2-wire tip commander or 3-wire tip-commander that allows loop and RCD testing.
Time delayed (S-type) RCDs As the changes to BS7671:2008 (also know as the 17th
Edition) have
come into force, the requirements for residual current device (RCD) protection of circuits has increased. In situations where multiple RCDs occur in an installation, the need to discriminate or co-ordinate when the RCDs will trip has become more important. If a 100mA RCD and a 30mA RCD are protecting the same circuit (e.g. one at source and one on the individual circuit) and a fault above 100 mA occurs, it may not always be the case that the 30 mA RCD trips fi rst (e.g. the 100 mA RCD could have a faster response time in the case of a fault). In this situation, a time delayed or S-type RCD is re- quired at the source of the installa- tion so that the 30 mA RCD has time to trip and, if the problem is caused by a none RCD protected circuit, the supply is still safely disconnected. Not all installation test instruments have the ability to check time de- layed or S-type RCDs. Therefore as RCDs become more commonplace, it is useful to have a test instrument that has the ability to test them. All
Accessories: page 1.35
Safety CAT Ratings Transients are very fast, high energy spikes that can occur on the mains power supply. Low energy transients can be caused by simply turning on a switch to a circuit or electromag- netic interference while high energy transients can be caused, for exam- ple, by a powerful motor stalling or a lightning striking a power line. Transients can have a variety of ef- fects which could include blowing the protective fuse in the appliance,
The higher the CAT rating of your test instrument, the more protection it will give you in the case of a fault occurring on the system under test (e.g. A CAT IV/300 V installation test instrument provides signifi cantly more protection to the user in the case of a fault than a CAT III/300 V installation test instrument). All Metrel’s MI 3000 series multi- functional test instruments are rated CAT IV/300 V. CAT IV 300V means that the instrument is suitable for testing up to CAT IV locations up to 300 V between line and earth and, due to the relationship set out in IEC/EN 60364, testing in CAT III lo- cations up to 600 V between Line and Earth.
Metrel’s multifunctional test instru- ments and single function live circuit testers have the ability to test both general and time delayed RCDs pro- viding you with the peace of mind that you are prepared for whatever the future may hold.
Online Voltage Monitoring Built into all of Metrel’s MI3000 se- ries multifunctional installation test- ers is the online voltage monitoring function. This function displays on one screen the AC voltages and fre- quency occurring between L to PE, L to N and N to PE (single phase sys- tems) and L1 to L2, L2 to L3 and L3 to L1 (3-phase systems).
This feature is very useful for fault fi nding on systems e.g. quickly iden- tifying incorrect connections, dis- connected wires and incorrect volt- ages.
causing light bulbs to blow, causing insulation between conductors to break down and, in the case of high energy transients causing appliances connected to the supply to set on fi re or produce dangerous sparks. The less protection provided against these transients enables higher ener- gy transients to occur (i.e. If lightning strikes the power lines, you would not expect the full fault voltage to occur at the power supply socket on the wall in your house). The level of danger due to transients is therefore divided into categories. This is illus- trated in the diagram below:
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