Pieter Mostert Posted October 27, 2014 Report Share Posted October 27, 2014 This is mostly an electrical wiring question. I've been trying to get quotes from electricians to put in a dedicated circuit for an old Paragon TnF-82 kiln I bought recently. According to the Paragon website, I need 6-gauge copper wire and a 50 amp breaker. However, I'm in South Africa, where electricians refer to wire sizes in terms of the cross-sectional area in millimeters squared, rather than the American wire gauge system. 6-gauge wire has a cross-sectional area of 13.3 mm^2, but according to the electricians I've spoken to, I need 10 mm^2 wire (slightly less than 7-gauge) for a 50 amp breaker, or 6 mm^2 wire (between 9 and 10 gauge) if I use a 45 amp breaker.At first I thought this was too small, but according to Wikipedia, this may be fine, depending on the type of insulation (the ampacity for 7 and 9 gauge wire isn't given, so I'm interpolating). I also doubt the electricians I've spoken to are trying to buck our electrical codes. However, if anyone with experience wiring kilns has a differing opinion, please let me know.My question is this: is it OK to use a 45 amp breaker? Apparently 50 amp breakers are harder to come by, and this would be cheaper, although I may put in 10 mm^2 wire anyway, just to be on the safe side.My kiln specs are slightly different from those on the Paragon website, so I've attached a photo of the electrical data plate, in case this helps. Link to comment Share on other sites More sharing options...
Mark C. Posted October 27, 2014 Report Share Posted October 27, 2014 Your kiln plates says 33 amps-this is the key part. A 45 amp breaker will work fine for 33 amps. You need a margin of safety and this is plenty. Except for one more thing- The larger question is how long is the wire run? You did not mention this key fact. The further the run the more amps are lost. If the run is short (less than 25 feet) I think you will be fine but if its 75-100 or more then there is loss to figure in. Mark one last note using larger wire is just fine-Its the right breaker as that protects the wire from overheating. For most this tecnical stuff is beyond the scope of general knowledge as it applies to electricians really Back here in the states many kilns (old schools ones) are say 48 amp on the plate which means a 60 amp breaker which # 6 wire is rated for(in this applaction a 50 amp will not work). As you noticed the insulation type is also another element when figuring this. I like THHN wire fo most wiring jobs. How many conductors and what size/type of conduit also is a factor. Larger means cooler in most cases. heres a chart with the specs http://www.cerrowire.com/ampacity-charts Link to comment Share on other sites More sharing options...
Guest JBaymore Posted October 28, 2014 Report Share Posted October 28, 2014 I don't know about South Africa, but here in the States many electricians are used to "home apliances" kinds of installation.... not kilns. They are used to clothes dryers and electric stoves and sometimes electric heat. The high duty cycle of a kiln at the top end of the firng (basically ON all the time) is not something that they typcally deeply understand. So they may be basing their ideas on their trove of experiental knowledge. Typically...... unless you find someone who KNOWS kilns..... follow the kiln manufacturer's info. If you have to err... err on the side of too large wire and too large a breaker . BTW... Mark knows what he is talking about (above). best, .......................john Link to comment Share on other sites More sharing options...
Pieter Mostert Posted October 28, 2014 Author Report Share Posted October 28, 2014 Mark, thanks for the advice. The wire run is about 7 meters, so less than 25 feet. John, I had to explain to one of the electricians what a kiln was for. Another guy kept calling it a kilt. Link to comment Share on other sites More sharing options...
neilestrick Posted October 28, 2014 Report Share Posted October 28, 2014 Code here in the US says that kiln must be on a breaker that is 25% greater than the draw of the kiln. At 33 amps draw you need a breaker that is 41.25 amps. That doesn't exist, so you go to the next size. In the US that's a 50. For you the 45 will be fine. As others have mentioned, if there's any question about the wire size, go with the larger. Personally, I would not trust 9-10 gauge wire for 45 amps. Link to comment Share on other sites More sharing options...
Pieter Mostert Posted October 28, 2014 Author Report Share Posted October 28, 2014 Neil, out of curiosity, why does Paragon recommend a 50 amp breaker for a kiln that draws 30 amps? (this is according to specs on the Paragon website. As I mentioned above, my specs are slightly different). 30 amps + 25% gives you 37.5 amps, so wouldn't a 40 amp breaker be enough? Link to comment Share on other sites More sharing options...
neilestrick Posted October 28, 2014 Report Share Posted October 28, 2014 Neil, out of curiosity, why does Paragon recommend a 50 amp breaker for a kiln that draws 30 amps? (this is according to specs on the Paragon website. As I mentioned above, my specs are slightly different). 30 amps + 25% gives you 37.5 amps, so wouldn't a 40 amp breaker be enough? At 30 amps, 125% is 37.5 amps, so a 40 amp breaker is good. I'm not sure why they would recommend a 50 for that. But at 33 amps, 125% is 41.25 amps, which means you go up to the next available size, which is a 50 amp breaker. Functionally you would be fine with the 33 amp kiln on a 40 amp breaker, but sticking with the electrical code you have to go to 50 amps. Code also says that they should be on a breaker no more than 50% greater than the draw, which puts the 33 amps at a 49.5 amps, so the 50 is good there, too. Link to comment Share on other sites More sharing options...
Pieter Mostert Posted October 28, 2014 Author Report Share Posted October 28, 2014 I hadn't thought of going with a 40 amp breaker (not sure if SA electrical code allows this). In that case, I'd feel better about 6 mm^2 wire. But I'll probably stick with a 45 amp breaker with 10 mm^2 wire, unless there's a huge difference in price. Link to comment Share on other sites More sharing options...
Mark C. Posted October 28, 2014 Report Share Posted October 28, 2014 I would go higher than the 40 amp breaker-what matters is the wire size. I am not familiar with metric wire sizes. What does the electrical code in S.A. say? Mark Link to comment Share on other sites More sharing options...
Pieter Mostert Posted October 28, 2014 Author Report Share Posted October 28, 2014 Do you mean S.A (South Africa)? I haven't been able to find tables specific to South Africa, but according to this UK table, 6 mm^2 wire should be fine on a 45 amp breaker provided the wire has an insulation temperature rating of 70 degrees C. So never mind the 40 amp breaker idea. Link to comment Share on other sites More sharing options...
Mark C. Posted October 28, 2014 Report Share Posted October 28, 2014 Yes I did sorry about the typo. Mark Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.