Chalkie76

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?

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

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.

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

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

Iooking at the replacements they are rated at 13amp and I’m drawing <10amps on 2.2kw elements so should be plenty of play. What was the solution you were thinking of that would drive a more robust relay? I actually love how simple this kiln is and replacement parts seem to be quite cheap and readily available (if you know where to look)! Hopefully once I replace the regulator and count the cycle clicks on each setting I’ll be able to come up with a firing schedule that doesn’t nuke my mugs anymore!! I’m Still tempted by the PID controller - in your opinion are they as straightforwards as they are marketed?). thanks again

Thanks Peter all makes sense and it’s done well to last as long as it has considering it’s just a piece of metal bending! I think maybe me increasing the spec of my elements has bitten me here as previously the regulator would have been turned to max much earlier in the firing but now I have to hold at 60% for several hours to keep the temperature from sky rocketing - that’s a lot more clicks than its used to! I had previously considered buying a “plug and play” pid controller but got put off by not understanding how it all works, now I’m thinking my regulator on full and allowing a plug and play box SSR to regulate might be a good option now. or a new kiln……

Aha! An energy regulator- seems obvious now, so basically the control knob regulates the current being supplied to the elements by switching the power on and off for longer/shorter intervals much like a relay?

Yes it is and the only other connections in the kiln from there is to the elements and lid safety switch and obviously the power coming in. thanks for replying

After receiving some excellent help during the summer regarding my elements I’m back again with a new problem….. It appears that now the kiln fails to cycle at some point and gets stuck on full power, it stops clicking and the temperature rises at a rate of 250 degrees per hour even when the dial is set to “2.5” which I think should be roughly 60%. Everything I read online says I need new relays but I’m wondering if my kiln even uses relays or if it’s an infinite switch or possibly something else? The kiln is a Cromarty CTL-17 and it’s over 40 years old but is structurally sound with new elements so I’d really like to bring it back to use. how can I tell if my kiln uses relays or an infinite switch? The only thing connecting the elements to the “power dial” is in the picture attached, anyone any idea what it is? Thanks in advance

In my case the kiln is not on a ring main and is actually on a radial so maximum load would be on just one cable and Im pretty sure this is just a standard 2.5mm copper core cable so I think that restricts things to 16amps. I don’t think I should go up as high as 3kw for the elements as there are other things (small things like phone charger, Alexa, lighting and a security camera on the same circuit). using the logic of watts per square inch in one of the posts above if I change to 2.5kw elements the heat potentials would be 3.8 watts per square inch which is line with current cone 10 kilns so allowing for degrading over time my kiln should continue to reach cone 6. I think reading all the excellent advice and help on here that I will ask Cromartie to custom wind either 2.5kw or 2.8kw elements. I have no idea how to change the wiring from parallel to serial or if that’s even possible for my little kiln but again will ask Cromartie. I will change the rating on the plate to show the new Kw to avoid any confusion further down the line. Again thanks to everyone for helping me understand what I have and also what I need.

In reply to bill the total resistance at the cord end is 26.5. Kiln interior is 17 litres and dimensions are 28cm accross by 22cm tall, the kiln brick is 3.5 inches thick. The lid had the fibre replaced when I purchased it and it seems to compress into the cavity quite well. I did test fire on full last week and here is the rate of climb for an empty kiln. All values are centigrade 1hr 760 2hrs 970 3hrs 1100 4hrs 1160 5hrs 1210 5hrs 40 minutes cone 6 bent at 1228 so it is capable of reaching cone 6 it just struggles for the last 50 degrees or so

Thanks Bill I will try to do this. I’ve turned off the power at the fuse box and removed the power cable from the switch, next steps: 1. reconnect elements 2. set to high 3. push the plunger on kiln sitter Select resistance on multimeter and contact red to “live” and black to “neutral” on the kiln cord? Is this correct? thanks for your help

I have already asked Cromartie and when I mentioned my readings to them they said the resistance when cold isn’t really useful to determine if they are worn or not and to just buy replacement’s if firings are taking longer. But I’m concerned that the new 2kw elements will perform worse than the existing ones so I have gone back to them again. (They have asked for some pictures so waiting to hear back from them). The more things I test the more confident I am becoming that the elements currently fitted are NOT 2kw. I just don’t know how to prove it for sure. my real question is: is it dangerous to have higher rated elements in a kiln? Voltage supply tested at 244v. 13amp fused switch connected 20amp breaker Thanks again