Has a controller, he uses it to ramp up over several hours so that peak load should be on E7 rates, he's talked about the thermocouple for it, and calibrating using cones.
larger, his is 11kW
Yes, it is quite well insulated, as I mentioned I gave him an energy meter which can clip on the tails from the Henley blocks, but he's never mentioned how much it costs per firing ... though it did show him the cost of leaving the pond pump/UV treatment on 24x7
Maybe, I was more concerned that he doesn't do anything daft with the wiring, that what results that achieves
When he upgraded the controller a couple of years back to one that uses external solid state relays (DIN rail mounted TRIACs or similar I suppose) they recommended special fast acting fuses to protect them, turned out the fuses were more expensive than replacing the 'relays'
You could use another known load, such as a kettle and a 2kW heater, to work out what the supply impedance is at the kiln, or at least to cross-check the results if you think the kiln might not have been running at full blast.
If you're using CFLs or fluorescents with electronic control gear, that won't notice. Filament lamps OTOH will amplify the effect.
Re b, then an estimate with current and voltage drop will do. Easiest if you have a clamp meter.
Even if you use a 70 degree PVC k factor of 100, then its still big enough, so it does not really matter in this case.
Bit more detail here:
formatting link
here
formatting link
> (Is this cable also exporting an equipotential zone to the room with the
The main issues is if there is access to an independent earth at the workshop (so unfinished floor, metal services entering the building from the ground, metal frame etc). The since you would have that in proximity to the PME earth, you would need a main equipotential bond between them, which typically means a copper equivalent of 10mm^2 for the bonding over and above that required for the CPC. (which given the substantial size of armour with 4 core SWA, I think you can actually meet the requirement with just the armour).
Probably worth checking for the fault condition where it is the suppliers PME earth introducing a dangerous potential into the workshop.
Type C I presume you mean?
It probably would not help anyway since it sounds like this was an overload related trip and not an fault current one. Hence both type B and C breakers would have the same thermal response anyway - so its pot luck as to which goes first. (sods law always dictates its whichever is the biggest PITA to go and reset!)
Hmm - the standing joke in the power electronics I was involved with (fork trucks) - was that the semiconductors were there to protect the fuses! - it always seemed to work out that way
Without actually running some sort of data logger that shows you 'time on' and 'time off' for the elements it's hard to be certain, but my gut feel is that the odd 5v subtracted from 240v (say 2% difference) isn't going to make that much difference to the power from the elements. I guess w=vi.... but then, the element's R will vary with temperature....
No ... concrete base, wooden frame, corrugated metal cladding to outside, if there's water plumbed in, I'm pretty sure it'll be in plastic, more questions that'll probably take days for a reply!
"checking for"?
I can see if the supplier's earth was faulty, there'd be plenty of metalwork to touch, the case of the kiln is all metal, which I assume is earthed rather than double insulated, he'll tend to have damp clay in hand on the wheel and the pugger
I did.
Always happened overnight when it'd had a few hours of intermittent operation to warm up the MCB ...
I've use FF fuses to protect mains switching power MOSFETs in one of my designs. Not yet had the race to see which blows first though. Heating elements don't normally have any switch-on surge, so you can fuse the current quite closely, but pay attention to the fuse's own power dissipation when close fusing.
MCB's are pretty damn fast too if you run into the fault protection zone (magnetic trip area). Where I had an expensive X10 DIN rail dimmer, I put a 3A Type B MCB next to it. However, it's no longer dimming mains filament lamps (they're now all low voltage), so that shouldn't be an issue anymore.
Checking if there is a way of accessing an independent earth in the workshop. If there is, then whatever it is (pipes etc) need to be included in the main equipotential bonding. Hence that will also need to be carried on the SWA CPC.
There is a (rare) failure mode with PME supplies, that a loss of suppliers Neutral (the so called Protective and Neutral conductor that comes into the building), then your installations neutral and hence earth will be left floating, and connected to live via all your appliances.
This could result in live casework on the kiln. This becomes dangerous if you can touch something else that is still connected to a real earth. If all the stuff around you is only earthed via the PME earth, then it should all be sat at the same elevated voltage, and hence not pose a direct shock risk.
Yup, especially with slow start - that could push it well into the cycle.
Is there any reason why you can't use an RCD to provide protection and use a local earth?
I guess I would "weigh" up the cost of cables csa vs cost of lost power over a number of years, given expected use of the kiln, to pick the optimum size of cable in terms of cost.
That would be quite straightforward, if it there was any benefit.
Replacing the existing cable is not really on the cards, its been buried for many years, the workshop and garden have grown up around it. Besides buying a replacement with a total CSA greater than 4x16mm^2 wouldn't be cheap.
The question was really around whether it was allowable to do the doubling up, or just to stick to the status quo, rather than anything else.
Having done a few calcs then it seems that you cannot double the cores up on a C type without using a RCD at the house end unless your Ze is much less than 0.35.
I'll look into fuse alternatives but I do have to do some work as well!
When I had my resistance numbers out by a factor of 100, I'd looked into something like this
formatting link
that there never was a good reason for the C type, I suspect going back to the B type will be easier, I've had no further email replies from dad, so I suspect a visit at the weekend might be called for.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.