HOMEBREW Digest #5228 Thu 06 September 2007

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  Re: Pre-chiller: plate or immersion? (Mike Dixon)
  GFCI's ("A.J deLange")
  GFCI internas ("Thomas Rohner")
  MALT Turkey Shoot 2007 (Jack Mowbray)

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---------------------------------------------------------------------- Date: Thu, 06 Sep 2007 04:03:42 -0400 From: Mike Dixon <mpdixon at ipass.net> Subject: Re: Pre-chiller: plate or immersion? I think Danny' suggestion for chilling sounds like a good idea. I still used an immersion chiller and due to the hot water temps (84F) here in NC, we tried an immersion prechiller going to an immersion chiller with satisfactory results. It took awhile but were able to cool 12 gallons to about 72F. However, that was still a slight bit higher than where I wanted to pitch. Several people use immersion pumps and an ice water recirculation to finish chilling the wort after the initial heat is removed. Being exceedingly frugal I setup a bottling bucket with a very inexpensive drill mounted pump (6.5 gpm for a cost of $5) and after I got the wort below 105F (about 12 min on 6 gallons with 84F tap water), I setup the drill pump ice water loop and was able to get to 64F a short while later. Still not quite my target, but within a hour or two in the fridge the batch was ready for pitching. So if you are using the plate chillers in series, I would chill with one plate using tap water, and then the other plate using an ice water recirculation. Just use enough water to allow the pump to operate properly and the recirculation system will use the least amount of ice. My one experience with a plate chiller did not give excellent results so I stuck with an immersion chiller. Cheers, Mike Dixon Wake Forest, NC Return to table of contents
Date: Thu, 06 Sep 2007 13:17:00 +0000 From: "A.J deLange" <ajdel at cox.net> Subject: GFCI's A couple of thoughts on this subject stimulated by responses to the original question: 1. The earthing wire does not go through the GFCI current sensing transformer. Thus leakage from hot or neutral to the earthing wire can cause a trip. This also means that the GFCI can be used without the earthing wire and in fact the NEC allows GFCIs to be used on unearthed circuits in some circumstances (406.32(D)(3)(c)). Therefore if the heatstick has been wired so that there is leakage to the earth wire removing the earth wire may solve the problem. It would be much better if the heatstick were repaired so this leakage is not present because the earth wire is there to convey fault current back to the source. Take it away and there is no path except possibly through the user and now the GFCI is being relied upon to protect the user from becoming that path. 2. The test button does work when the earth wire is removed. It switches a resistor into the circuit between the load side hot and source side neutral. 3. Modern GFCIs are designed to trip if the neutral and earth are joined on the load side. Thus if someone should wire earth and neutral together at the heatstick or if earth and neutral should come into contact somehow a newer GFCI would trip. The neutral and earth must only be joined at the service entrance. The wiring for a heatstick (or other load) should be phase (hot, black, red, blue) to one side of the resistive element, neutral (grounded, white, gray) to the other. The earth (grounding, bare, green, green with yellow tracer) wire should only be connected to the metallic shell of the device. Note that I have used earth and neutral rather than grounding and grounded in the hope that this terminology (borrowed from the Brits) will reduce confusion regarding the names of these conductors 4. Capacitance leakage can result in imbalance current which can trip a GFCI but 6 ma or more capacitative current requires an impedance of 2K or less which means about 1.3 ufd capacitance. That's a lot given that cables usually run a few pf per foot. 5. A GFCI outlet is often wired as the source for several conventional outlets which it can also protect. But any leakage anywhere downstream of the current transformer will trip. This often gets to be a real nuisance where an interior GFCI feeds outlets in places exposed to dampness (garages, crawl spaces) because often the home owner is not even aware that there are other outlets in the chain (sometimes you will see little "GFCI Protected" stickers on conventional outlets. This is clue that these outlets are daisy chained from a GFCI outlet. 6. One can buy "extension cords" with GFCI breakers built in and one sometimes finds these "in line" GFCI units in appliances which are used in damp locations. One of these for each heatstick may be an approach that solves the problem. A.J. Return to table of contents
Date: Thu, 6 Sep 2007 17:03:01 +0200 From: "Thomas Rohner" <t.rohner at bluewin.ch> Subject: GFCI internas Hi again first about the wiring. The neutral and the grounding of your house are connected at your main breaker box. So without any load, neutral and ground should be the same anywhere in your house. Now lets start drawing current at the end of your installation. If you measure now between the neutral at your load and ground, you will have a small voltage there. This is because your neutral isn't a superconductor and therefore has a small resistance. After Ohms law that's U=R*I, so the higher the current and the resistance, the higher the voltage. If for example the neutral in your load (appliance, heatstick) touches ground somehow, you get quite a current down to ground if its shorted. That's I=U/R where R is very low in a short circuit, so I can get quite high, even with U quite small. (For example U=0.3V R=0.1 Ohms you get a current of 3000mA while the GFCI trips at 20mA or even less) Now to the working principle of a GFCI. It's somehow like a relay, but then not. It has a magnetic coil that attracts sort of a plunger that will break open the two conductors.(and stay open until manually closed again.) Now the coil is quite special, because it has two insulated windings, wound parallel. One winding has the current running to the phase through it, the other the neutral in reverse direction. As long as the current is the same in both windings, the magnetic fields will be substracted from each other equalling 0 because of the opposite flow direction of the current. The breaker won't trip. As soon as the current in both windings isn't the same anymore, the magnetic field isn't 0 anymore. If the difference is big enough, the breaker trips. Thats how it works in principle, as you can see, ground was nowhere in the equation. But then it is used for the test button, and it wouldn't make any sense to remove it from the GFCI anyway. Either your heatsticks leak somewhere, or their neutral gets connected to ground. If their neutral is connected to ground, the only thing you can do is take a really thick cable from your main breaker to your heatsticks. Or use heatsticks that are well insulated. (would be my choice) And make sure that neutral and ground are not connected together in your heater control circuit. I had to learn this the hard way during my education, i was troubleshooting a heatplate for smd thickfilm cirquits. At some point i had to use a oscilloscope. I thought well, neutral is the same as ground, so i can connect the oscilloscopes ground to the neutral of my heatplate. I was wrong(as you can see in the first paragraph), soon i had some software developers standing around me with this special sparcle in their eyes.(That says i could kill you) It turned out that their multiuser developement system was on the same phase as my heatplate. It wasn't very prudent of them to use the same phase as us hardware dudes. I think they changed it after this incident. At that time,(1985) those developement systems didn't seem to have a autosave function either. (It was a 68000 with 1Meg Ram and a 40Meg HD runing on Unix, they had 8 terminals and worked with crosscompilers and editors. This was quite state of the art back then. That was also the time when a "home PC" like the C64 had 64kB Ram and a floppy, if you were lucky.) Cheers Thomas Return to table of contents
Date: Thu, 06 Sep 2007 12:46:17 -0500 (CDT) From: Jack Mowbray <jmowbray at verizon.net> Subject: MALT Turkey Shoot 2007 Maryland Ale and Lager Technicians (MALT) are again pleased to announce their 3rd Annual Turkey Shoot* Homebrew Competition. This will be a BJCP sanctioned event. Cash prizes will be awarded for Best of Show as well as for 2nd and 3rd place. There will be sponsored prizes awarded to individual category winners. The competition will be held Saturday, November 10th at Clipper City Brewing Company in Baltimore, MD. All BJCP beer categories will be accepted and the deadline for entries is November 3rd. Additional information, rules, entry forms, and bottle labels can be found at the MALT website: http://www.maltclub.org We could use some more BJCP accredited judges for this event. Anyone who is interested in helping with the judging should contact: Mike McMahon fishandbrew at comcast.net *no live poultry will be harmed during this event Return to table of contents
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