Chalkie76 Posted January 17 Report Share Posted January 17 I have posted a couple of times about my ancient (now hated) kiln. I hadn’t used it for a couple of months and I just got round to replacing the energy regulator and did a repair to the kiln lid and now my kiln trips my house RCD as soon as I turn on the energy regulator. I have checked the wiring with Cromartie who supplied the new regulator (and made the kiln 40 years ago) and it all seems fine. They suggested bypassing the lid safety switch to see if that was faulty but it still trips. What other faults could be at play? I’m in the UK on 240v AC. Kiln is currently on a 13amp fused plug on a radial circuit back to a 20amp breaker protected by an RCD. (Kiln was previously hard wired to a 13amp fused outlet but I’ve put the plug back on for testing). I have tested other appliances on the circuit and it’s fine. the kiln itself is 17 litres with a kiln sitter and infinite switch powering 2 sets of elements rated at 2.8kw in 18 gauge wire, wired in parallel. Current resistance readings are 22.8 top 22.7 botttom. There is continuity throughout both sets. kiln sitter has new sensing rod and power flows to the infinite switch when the latch is engaged and power button depressed. (pilot light came on and multi meter detected 240v at the terminal). I have tested the ground pin on the plug and there is continuity between that and the metal casing of the kiln. Does anyone have any suggestions on what my next steps could be? The wire I robbed to bypass the lid switch was from the pilot light and it’s slightly thinner than the other so I’ve ordered some heavier gauge incase it’s that but I’m doubtful…… https://www.backerelectric.com/shop/product/cooker-control-13020.asp Quote Link to comment Share on other sites More sharing options...
neilestrick Posted January 17 Report Share Posted January 17 I believe the RCD is essentially the same as a GFCI, and kilns will trip those. They are not recommended for use with kilns. Quote Link to comment Share on other sites More sharing options...
Chalkie76 Posted January 17 Author Report Share Posted January 17 Prior to changing the infinity switch the kiln worked ok for over a year on that setup - never tripped once. Reading up on the GFCI they do sound like they serve a similar purpose - can I ask what is it that makes a kiln generate an imbalance of current? I actually think it’s a requirement by law in the UK that all sockets have RCD protection so hopefully this isn’t the problem I’m facing! Thanks for your reply Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 17 Report Share Posted January 17 (edited) @Chalkie76 I have been wondering how long it will be till it surfaces since Neil posted the L&L finding about minute conductivity and kiln brick. Here in the US, kilns aren’t installed on GFCI circuits or RCDs. In the UK the entire household might be protected by an RCD. This is all relevant because even if your kiln did not previously trip the RCD, the brick may now be better connection and may now trip the RCD. If this is the case ( big if here) to test for it I would disconnect the elements from the power source completely and see if the kiln, controller etc…. Operates without tripping the RCD. It won’t heat, I know but if this cures the issue then testing with one set of elements and the second (if present) disconnected could isolate this to one set of elements. Once isolated then one could inspect the elements and grooves in the brick closely to See if there are debris in them causing enough leakage to trip the RCD. Are the brick damp from lack of use? If they prove to be the culprit (big if) kilns end up to be difficult to protect in this way so if code allows then not being powered by an RCD protected circuit may be necessary. I believe the UK has struggled with this issue for a while with new LED lighting, car chargers, inverter powered equipment and now has several RCD devices designed to trip with pulsating DC leakage that may now be required. I think the first step would be to identify if this outlier type problem is occurring for you because of the brick which simply means isolate the elements at the control relays. If the answer is yes, then the magnitude of the conductivity could be measured for a better idea of how to successfully fix this with confidence. If this ends up being the cause and the reason for increased conductivity anything in the power chain such as a dirty ceramic insulator can cause leakage so careful examination and cleaning might be necessary.If it is due to moisture in the brick due to off time or layup of the kiln, then a plan to dry it out might be an effective fix. An odd problem, but sort of easy to at least test for. Edited January 17 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Chalkie76 Posted January 17 Author Report Share Posted January 17 I never even considered dampness - this could indeed be a problem, kiln is in an outdoor studio northern Scotland so wet and cold is the norm. I’ll run my heat gun over the elements tomorrow and put the heater pointed at the kiln for a few hours see if that makes a difference. Or take it indoors for a few days. Thinking about it the lid was off for an about a week and this was probably a silly mistake!!!! Those kiln bricks are like sponges….. If no difference I’ll disconnect the elements and test further as suggested. thanks for the explanation & suggestion. Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 18 Report Share Posted January 18 (edited) 2 hours ago, Chalkie76 said: I’ll run my heat gun over the elements tomorrow Maybe dry out all the porcelain insulators as well. If they are damp they will likely trip this. If you can get it working at any level a nice preheat likely dries the kiln best overall. Then never leave the kiln open again. Edited January 18 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
PeterH Posted January 18 Report Share Posted January 18 (edited) For what it's worth RCDs seem to trip at a higher current.. What is the difference between RCD and GFCI? https://www.quora.com/What-is-the-difference-between-RCD-and-GFCI They essentially are two names for the same device. In the UK and in Europe when English is used it is called an RCD (residual current device). In the US it is called a GFCI. Now there are differences between US and Europe. In the US the triggering current is 5 mA. In Europe it is 30 mA. In the US they are electronic while in Europe they typically are electro-mechanical. In the US they often are in the sockets while in, Europe they are more commonly in the panel. More details in https://www.tlc-direct.co.uk/Technical/Distribution/RCD.htm The British Standard requirements for RCDs (BS EN 61008) states that the RCD should operate between 50% and 100% of its rated tripping current. That is 15 mA and 30 mA for the 30 mA RCD. Most 30 mA RCDs operate at levels between 18 mA and 23 mA. Edited January 18 by PeterH Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 18 Report Share Posted January 18 Does the power go straight from the plug to these wires or is it coming from that silver box? Can you post a photo of inside the box? The wires zip-tied up look more suspicious than power going through the bricks to earth. I am pretty sure all UK homes go through an RCD and there's quite a few of these old Cromartie kilns about but I have never heard of brick conductivity being an issue. Quote Link to comment Share on other sites More sharing options...
PeterH Posted January 18 Report Share Posted January 18 Some discussion on the regs in https://community.screwfix.com/threads/rcd-protection-or-not.250927/ Including a comment on the (2005?) regs It also confirms my suspicion that cookers are among the items least likely to be on a RCD, so it might be worth checking in your supply box. (Basically because UK cookers aren't usually on ring mains.) If this is the case it -- and you have trouble getting the kiln fully dried out -- it could be worth considering a preheat on a RCD-less cooker feed. Quote Link to comment Share on other sites More sharing options...
Chalkie76 Posted January 18 Author Report Share Posted January 18 Thanks to you knowledgeable folk my little kiln is now happily ramping up at sonic speed again. It was indeed damp!! I propped the lid (which was only possible as I bypassed the lid safety - @High Bridge Pottery (which is the silver box with the cable tied wires) and then I stuck my heat gun nozzle in the bung hole - it fitted perfectly! Ran it a few times for 5 minutes and each time I lifted the lid tiny little steam clouds puffed out!!! I am so relieved I don’t have to explore the RCD or current leakage issue just yet! But fyi my cooker has its own dedicated fuse but it’s still protected by the RCD. now I’m debating if I should hook up the lid switch or leave it out as I quite like the idea of propping the lid to reduce the speed the kiln heats up but I do t like the idea of accidentally touching the elements when the kilns power is on……. i guess I would only make that mistake once…… I will never leave the lid open or off for anything (other than loading and unloading) ever again! thanks again everyone Bill Kielb, PeterH and High Bridge Pottery 3 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 19 Report Share Posted January 19 I didn't think being damp would change anything that much but good to know it does Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 19 Report Share Posted January 19 9 hours ago, High Bridge Pottery said: I didn't think being damp would change anything that much Ground fault devices were created just to detect very tiny flow of current. While not exclusive most common source of leakage - damp or wet connections. In North America code generally requires them for receptacles within six feet of a source of water to minimize potential of electric shock. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Chalkie76 Posted January 19 Author Report Share Posted January 19 Actually looking for a little more advice on re-wiring @Bill Kielb I need to create 2 jumper leads with spade connections and I’m not sure what the current ones are made of. Most of the components online seem to be tin/nickel & copper with no temperature rating. Should I therefore be looking for steel ones? Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 19 Report Share Posted January 19 10 minutes ago, Chalkie76 said: Actually looking for a little more advice on re-wiring @Bill Kielb I need to create 2 jumper leads with spade connections and I’m not sure what the current ones are made of. Most of the components online seem to be tin/nickel & copper with no temperature rating. Should I therefore be looking for steel ones? Normal high temperature crimp connectors are plated but generally do not have insulation which makes them more or less high temperature. Higher quality stuff has welded seams for the crimps. You really only need to design for the area you are working in. Element leads usually use high temp wire - MG traditionally but of late we see kiln manufactures using other types of lesser rated wire but the designs have improved for cooling and use of radiation shields. I assume this is for the lid switch so matching the original wiring temperature and gauge requirement is generally fine unless it has been melting. The existing wiring is stamped with its temperature rating and gauge on the side of the wire so matching or exceeding that should be just fine. Welded barrel crimps are great but not necessary for small electrical loads IME. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.