Posted By Alan G Hi everyone, We use RCD Breakers on the end of each extension lead, drill’s as we plug them in to clients houses. As we are all aware we can self-test a RCD Breaker by pressing test and then reset, how do you prove and document that this type of basic self test is functioning correctly. Is there a way to calibrate them or can you PAT test them? Is a self-test sufficient? All is welcome. Regards Alan

Posted By Calum R Cameron Sounds like you are involved with some kind of building type works and therefore you should not be using an RCD. As they are electro-mechanical devices they are prone to failure and this may present a risk. Instead, you should be using a 110v transformer which is centre tapped to earth thus reducing the voltage reference to earth to 55-65v ac. It is unlikely that you would be able to justify the use of 230v in a risk assessment as the cost of 110v tools are comparable. Obviously - even before using 110v there is the battery tool option as they are very good these days. Please feel free to contact me if you require further help.

Posted By Micky Talk to a UK manufacturer of RCDs. They will have a technical department and will be able to authoritively answer your questions. Also try RS as they have equipment specification sheets for all the equipment they sell.

Posted By Ron Hunter To take the risk assessment principle to logical conclusion, you should give serious consideration to using battery operated power tools!

Posted By Barry Cooper RCD's are ok, 110v better, battery drills ideal. Trouble with RCD's they only protect you against electric shocks due to earth faults. Not those due to Live/neutral faults, and most drills these days are double insulated and have no earth conductor.

Posted By Barry Cooper The imbalance of current is only caused when for example you touch the live terminal and earth, so the RCD will trip. If you touch live and neutral there will be no imbalance, so the RCD may not trip

Posted By Calum R Cameron Geoff-just to point out as I am an ex electrician-The RCD recognises an imbalance between the phase conductors ie live and neutral. If the imbalance in current is sufficient then the RCD will open circuit. It is incorrect however to say that a standard fuse or MCB would provide any protection against an electrocution as a BS88 fuse has a fusing factor of around x2 which means it can take up to twice its rated current to rupture it. If the fuse was rated at say 32A it could take a minimum of 64A to rupture it-It takes 30mA to fibrilate a human heart and much less if you happen to be a cow. Fuses offer no protection to a person sustaining an electrocution. Here endeth the lecture. Cheers Calum Cameron MIOSH Dip2 OSH

Posted By Simon Ayee RCDs should be tested periodically as well as routinely. Periodic testing using suitable test equipment can confirm that the RCD operates at the correct current and within the correct time. The routine self test tells you if it works & the periodic test tells you that it works effectively. The manual self test should be carried out more frequently than the periodic test test. Presumably the frequency is covered in BS7671 for installations. Most portable RCD's I have used instruct you to self test before each use.

Posted By Jon Bradburn Hello All, I'm no expert but we have recently had several issues regarding RCD's and test frequency. I have found conflicting information but in a nutshell Portable RCD's should be self tested using the built in function on a regular basis (we go for before each use - not a difficult task is it and normally recommeded by the manufacturer) other sources state weekly / monthly / quarterly checks depending on application / environment etc. I found to consensus that a full checked should be carried out every 2 years by a 'qualified electrician', although some sources the 'competent person' was used. We have technicians who are not electricians but who are PAT trained, and would consider them competant to use an RCD tester (similar and sometimes incorporated into the PAT tester, given appropriate training. Given the cost of one of these units aginst price of a poratble RCD we have decided to replace RCD's evry 2 years - probably not cost effective if you have lots! As far as 'fixed' RCD's go The general advice I found was that less frequent testing was required as they are not subjected to the stresses of a portable type. Again application and environment are a factor. The 'norm' appears to be a 3 monthly user check and a full testing as part of the Fixed installation checks - be that 1, 3 or 5 years industry dependant. We have found www.pat-testing.info to be a good site for all PAT testing information. Though it does refer to the 'qualified electrician' as opposed to 'competent person' Hope this helps Jon