AeroElectric-List Digest Archive

Sat 09/26/09


Total Messages Posted: 14



Today's Message Index:
----------------------
 
     1. 04:57 AM - Why have a switch on ALT Field? ()
     2. 07:53 AM - Re: Welding cable (Chris)
     3. 09:40 AM - Re: Re: Why have a switch on ALT Field? (Robert L. Nuckolls, III)
     4. 10:18 AM - Re: Welding cable (Robert L. Nuckolls, III)
     5. 10:20 AM - Re: Why have a switch on ALT Field? (rvg8tor)
     6. 10:45 AM - Re: Why have a switch on ALT Field? (Ian)
     7. 10:53 AM - Re: Why have a switch on ALT Field? (Robert L. Nuckolls, III)
     8. 10:53 AM - Re: Welding cable (Sam Hoskins)
     9. 11:14 AM - Re: Re: Welding cable (halbenjamin@optonline.net)
    10. 11:27 AM - Hired wire-slingers (Robert L. Nuckolls, III)
    11. 12:16 PM - Mounting BATT/START Relays ()
    12. 12:24 PM - Re: Re: Welding cable (Robert L. Nuckolls, III)
    13. 03:23 PM - Re: Mounting BATT/START Relays (rvg8tor)
    14. 04:26 PM - Re: Re: Welding cable (Chris)
 
 
 


Message 1


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    Time: 04:57:08 AM PST US
    From: <bakerocb@cox.net>
    Subject: Why have a switch on ALT Field?
    9/26/2009 Hello Mike and Bob, The recent exchange of postings between the two of you on the subject of "Why have a switch on ALT Field?" has left me a bit baffled. Mike, your question dealt with shutting down an alternator by removing the electrical source to its FIELD. Figure Z 12 was the starting point for your question and presumably dealt with externally regulated alternators, but then you threw in the red herring of shutting down internally regulated alternators. Bob, your answer appeared to deal extensively with shutting down an internally regulated alternator by opening the B LEAD such as in Figure Z 24.. Mike, your response below indicated that you believed, as a result of Bob's posting, that there was a huge amount of electricity flowing through the wire to the alternator FIELD circuit in an externally regulated alternator and that therefore a switch rather than a circuit breaker would be needed to open that circuit. "You have given me the data i was looking for, I now understand why the switch is needed, it is due to potential high loads." It is my understanding that: 1) The alternator FIELD wire in an externally regulated alternator only carries a few amps of electricity. 2) Opening this FIELD wire with either a CB or a switch while electricity is flowing through this wire generates no huge electrical flow interruption issue. 3) The alternator B LEAD (in either an internally regulated or externally regulated alternator) can carry a significant amount of electricity and interrupting this flow through the B LEAD by opening the B LEAD brings up the issues that Bob dealt with extensively in his response. Mike if you will check some of the Z diagrams (Z 9 as well as Z 12 for example) you will see that there is both a CB and a switch that can interrupt the electrical flow to the alternator FIELD of an externally regulated alternator. And this is good. The CB provides the traditional protection to that wiring and the switch makes it possible to turn on / off the alternator FIELD as desired with no great concern regarding interrupting huge amperage flow. My airplane has both a CB and a switch (as do the Z figures) and the externally regulated alternator FIELD gets turned off by the switch during every engine shut down procedure while the engine is still running. Shortly after the alternator is turned off by the FIELD switch the low voltage light begins to flash telling me that that warning indication is working. I then turn on my essential bus** and then turn off the battery master and the radio master (yes I have one ##) to ensure that my Garmin 430W and my transponder continue to operate off the battery which is now feeding the avionics essential bus. The Garmin 430W and the transponder are essential for me to return to my home field inside the Washington DC SFRA. Please let me know if I have confused or clarified the issue raised by Mike's original question. 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." **PS: Yes I am aware that there are means of causing this to happen automatically with a diode, but the guy who wired my panel did not do it that way and I have been living very happily with what he provided because I understand the system. ##PS: Again this was given to me (after I paid big money to have the panel built), but I have access to the avionics that I need via an essential avionics bus so I have been living very happily with what he provided because I understand the system. ================================================ Time: 06:49:13 PM PST US Subject: AeroElectric-List: Re: Why have a switch on ALT Field? From: "rvg8tor" <rvg8tor@comcast.net> Bob, Thank you for the explanation, this really helps me understand the design better. I did post your reply on the VAF for all to read. I think this will add to everyones education. So if I understand what your post, the gist is that there is potential for excess voltage in some situations as to make a CB fail if used to cut the field to the alternator. I have heard others say CBs are not meant to be switches, but at my airline we routinely pull CB on certain items while the airplane sits between flights for several hours. Things like the radar, TCAS, VSI indicator. This use of the CB as a switch happens several times a day for each aircraft. It this an accepted practice since these are low voltage items. You have given me the data i was looking for, I now understand why the switch is needed, it is due to potential high loads. -------- Mike &quot;Nemo&quot; Elliott RV-8A QB (Fuselage)


    Message 2


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    Time: 07:53:56 AM PST US
    From: "Chris" <toaster73@embarqmail.com>
    Subject: Welding cable
    Where can you find the anchor brand cable? Any weblinks/supply you can point to. Thanks Chris RV-10 From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, September 24, 2009 3:54 PM Subject: Re: AeroElectric-List: Welding cable At 11:51 AM 9/24/2009, you wrote: I don't know about the Harbor Freight stuff, but when I was looking for welding cable, I did find a variety of quality in insulation. Some had an inner jacket, which I took to be a better quality, and some had not. Sam Thanks for reminding me of that Sam. A guy at a welding store told me that the two-layer cable lasted longer in the field. Little nicks in the outer jacket tended to propagate cracks through to the strands when the cable was flexed/ stretched. By making it two layers, the gap was a "crack stopper" while the inner layer maintained environmental integrity. http://aeroelectric.com/Pictures/Wire/4AWG_Welding_Cable_1.jpg It seems a logical explanation. Of course, the cables in our airplanes don't get stretched across gravel drives and run over by dump-trucks. The Anchor brand welding cable illustrated above has an HDPM outer jacket which is revered for its flexibility and toughness. Here's an excerpt from a wire catalog describing this insulation. Emacs! Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------


    Message 3


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    Time: 09:40:53 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Why have a switch on ALT Field?
    At 08:47 PM 9/25/2009, you wrote: Bob, Thank you for the explanation, this really helps me understand the design better. I did post your reply on the VAF for all to read. I think this will add to everyone's education. So if I understand what your post, the gist is that there is potential for excess voltage in some situations as to make a CB fail if used to cut the field to the alternator. That's not the bottom line . . . We should start with some design goals in mind. For all of my career in TC and OBAM aircraft, I've embraced and designed systems that meet traditional goals for any time, any conditions, On-0ff control of the engine driven power source(s). I have heard others say CBs are not meant to be switches, but at my airline we routinely pull CB on certain items while the airplane sits between flights for several hours. Things like the radar, TCAS, VSI indicator. This use of the CB as a switch happens several times a day for each aircraft. It this an accepted practice since these are low voltage items. This isn't about using breakers as switches, it's about meeting the design goal cited above. The b-lead breaker on an alternator COULD be used to disconnect the alternator assuming (A) the alternator is under control [producing 14 or so volts] and (B) the breaker is on the panel and pullable [many TC aircraft have push-only breakers]. The classical control philosophy for engine driven power sources has been a SWITCH in reach of the crew that offers control over the field excitation . . . always a low current, easy-to-manage task. This task COULD be managed by flipping a switch -OR- pulling the field supply breaker . . . it's your choice. There are other legacy design goals . . . like automatic and absolute control of the alternator in case of a failed regulator in an OV runaway condition. Figure Z-24 is but one of several recipes for success. When Z-24 was combined with alternators NOT designed and tested to withstand their own load-dumps that some builders experienced alternator failures immediately after turning them off while under load. You have given me the data I was looking for, I now understand why the switch is needed, it is due to potential high loads. No . . . its about dependance on pulling of a b-lead breaker for the purpose of taking a runaway alternator off line. This is a shaky design goal due to the fact that a failed alternator can deliver 100-200 volts in a runaway condition. Attempting to do this reliably with a 32-volt rated, pullable breaker would very likely fail the breaker. Further, pulling a b-lead breaker to mitigate an ov condition puts human perception, decision, reaction delays into the shutdown event. That's never been embraced by the TC aircraft world that I'm aware of. The issues before us are (1) design goals for control (2) design goals for automatic millisecond- fast mitigation of an OV event. You can pull a field breaker for (1) if you wish . . . but NOT a b-lead breaker for (2). Bob . . .


    Message 4


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    Time: 10:18:06 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Welding cable
    At 09:45 AM 9/26/2009, you wrote: >Where can you find the anchor brand cable? Any weblinks/supply you >can point to. >Thanks >Chris >RV-10 A local welding supply store will offer Anchor or a suitable equivalent. Some mention was made of a "200A inverter cable" from Harbor Freight. While these wires will probably have enough finely stranded copper for the task, the question to be asked deals with temperature characteristics and ruggedness of the INSULATION. Welding cable produced to an ATSM specification (as are most if not all American products) will do the job for you . . . I searched for Anchor outlets but without success after 20 minutes or so . . . however, the storefront where I purchased the pictured sample was offering Anchor brand cable at the time I bought it. That was several years ago. Shop around locally first . . . Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------


    Message 5


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    Time: 10:20:20 AM PST US
    Subject: Re: Why have a switch on ALT Field?
    From: "rvg8tor" <rvg8tor@comcast.net>
    My design goal is a system that is simple as possible but still meets capacity and redundancy goals (glass IFR bird). Thankfully I found Z12 and this design suits my need. My assumption not mentioned by me so far, is that I will have an alternator that will have a controllable filed with OV protection, be that with internal or external regulation. I never thought of controlling the alternator with the "B" lead. So just looking at the Z12 diagram I pondered whether I needed the switch for the alternator field, I was looking for way to simplify where I could. My CB panel will all be in easy reach by my right leg, the CB layout has 4 breakers at the end of two rows to make then stand out from the rest, I also plan to have them with colored collars, this would make finding them in the dark easy. Two at the end of the top row are for the primary and standby alternator fields. Two at the end of the next row control 12V power to the L/R P-mags respectfully. Also the two rows are not the same length, this also allows for identification in the dark. Top row is shorter, last two breakers are MAIN ALT then STBY ALT, easy to remember easy to find. I know a toggle switch will be faster to actuate than finding a breaker but not by much. So would elimination of the switch change the design goal of Z12, would I not still have a controllable engine driven power source? I guess from what I have read so far the answer is no. Even though the switch will be used very little, it is still required? -------- Mike &quot;Nemo&quot; Elliott RV-8A QB (Fuselage) Read this topic online here: http://forums.matronics.com/viewtopic.php?p=265125#265125


    Message 6


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    Time: 10:45:24 AM PST US
    Subject: Re: Why have a switch on ALT Field?
    From: Ian <ixb@videotron.ca>
    OK, now here's one more vote for "confused". I thought the circuit breaker was supposed to be rated at the output amperage of the alternator because it's that current that one wants to limit. My 40A circuit breaker would do nothing for me on the alternator field circuit. As I understand it, the switch is on the alternator field low-current 12V line (called IGN on my alternator) and the circuit breaker protects the output side (B lead). Mine is wired this way because it made sense. Ian Brown, RV-9A, Bromont, QC On Sat, 2009-09-26 at 07:53 -0400, bakerocb@cox.net wrote: > > 9/26/2009 > > Hello Mike and Bob, The recent exchange of postings between the two of you > on the subject of "Why have a switch on ALT Field?" has left me a bit > baffled. > > Mike, your question dealt with shutting down an alternator by removing the > electrical source to its FIELD. Figure Z 12 was the starting point for your > question and presumably dealt with externally regulated alternators, but > then you threw in the red herring of shutting down internally regulated > alternators. > > Bob, your answer appeared to deal extensively with shutting down an > internally regulated alternator by opening the B LEAD such as in Figure Z > 24.. > > Mike, your response below indicated that you believed, as a result of Bob's > posting, that there was a huge amount of electricity flowing through the > wire to the alternator FIELD circuit in an externally regulated alternator > and that therefore a switch rather than a circuit breaker would be needed to > open that circuit. > > "You have given me the data i was looking for, I now understand why the > switch is > needed, it is due to potential high loads." > > It is my understanding that: > > 1) The alternator FIELD wire in an externally regulated alternator only > carries a few amps of electricity. > > 2) Opening this FIELD wire with either a CB or a switch while electricity is > flowing through this wire generates no huge electrical flow interruption > issue. > > 3) The alternator B LEAD (in either an internally regulated or externally > regulated alternator) can carry a significant amount of electricity and > interrupting this flow through the B LEAD by opening the B LEAD brings up > the issues that Bob dealt with extensively in his response. > > Mike if you will check some of the Z diagrams (Z 9 as well as Z 12 for > example) you will see that there is both a CB and a switch that can > interrupt the electrical flow to the alternator FIELD of an externally > regulated alternator. And this is good. The CB provides the traditional > protection to that wiring and the switch makes it possible to turn on / off > the alternator FIELD as desired with no great concern regarding interrupting > huge amperage flow. > > My airplane has both a CB and a switch (as do the Z figures) and the > externally regulated alternator FIELD gets turned off by the switch during > every engine shut down procedure while the engine is still running. Shortly > after the alternator is turned off by the FIELD switch the low voltage light > begins to flash telling me that that warning indication is working. I then > turn on my essential bus** and then turn off the battery master and the > radio master (yes I have one ##) to ensure that my Garmin 430W and my > transponder continue to operate off the battery which is now feeding the > avionics essential bus. The Garmin 430W and the transponder are essential > for me to return to my home field inside the Washington DC SFRA. > > Please let me know if I have confused or clarified the issue raised by > Mike's original question. > > 'OC' Says: "The best investment we can make is the effort to gather and > understand knowledge." > > > **PS: Yes I am aware that there are means of causing this to happen > automatically with a diode, but the guy who wired my panel did not do it > that way and I have been living very happily with what he provided because I > understand the system. > > ##PS: Again this was given to me (after I paid big money to have the panel > built), but I have access to the avionics that I need via an essential > avionics bus so I have been living very happily with what he provided > because I understand the system. > > ================================================ > > > Time: 06:49:13 PM PST US > Subject: AeroElectric-List: Re: Why have a switch on ALT Field? > From: "rvg8tor" <rvg8tor@comcast.net> > > > Bob, > > Thank you for the explanation, this really helps me understand the design > better. > I did post your reply on the VAF for all to read. I think this will add to > everyones education. > > So if I understand what your post, the gist is that there is potential for > excess > voltage in some situations as to make a CB fail if used to cut the field to > the alternator. I have heard others say CBs are not meant to be switches, > but > at my airline we routinely pull CB on certain items while the airplane sits > between flights for several hours. Things like the radar, TCAS, VSI > indicator. > This use of the CB as a switch happens several times a day for each > aircraft. > It this an accepted practice since these are low voltage items. > > You have given me the data i was looking for, I now understand why the > switch is > needed, it is due to potential high loads. > > -------- > Mike &quot;Nemo&quot; Elliott > RV-8A QB (Fuselage) > > > > >


    Message 7


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    Time: 10:53:15 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Why have a switch on ALT Field?
    At 06:53 AM 9/26/2009, you wrote: <Snip> Please let me know if I have confused or clarified the issue raised by Mike's original question. Your words appear to paint a clear understanding . . . The problem with this (and many threads of similar discussion in the past) is the stirring of a LOT of simple-ideas (facts) into one pot of ill-conceived stew (no definition of design goals) and stirred over a hot fire ("don't do that or you're gonna die") with the unbridled enthusiasm (mis-interpretation of words). 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." Yup, you got that right. I notice that my response to Mike's follow-up hasn't passed through the server yet . . . but I hope it proves to be a useful clarification of how we . . . (1) start with design goals . . . (2) then craft an architecture that addresses design goals while . . . (3) eliminating single points of failure for extra ordinarily useful electro-whizzies as revealed by skillfully conducted FMEA. (4) Study and understand the specs for ingredients that go into recipes for success. (5) Select style, quality and a minimized quantity of components that go into the proposed recipe. (6) Verify that the recipe meets design goals. (7) Analyze subsequent failures to deduce root cause. Wear out? Mis-application? Robustness? Quality? Error of stating or conformance to design goals? Other? Answers to these questions may prompt a program review that goes all the way back to step (1). When one makes a career of this process, you eventually discover that it's a Mobius Loop which strives for archiving a host of lessons-learned while improving upon the best we know how to do. This is the essence of good design engineering as I've come to understand it. Its interesting but frustrating that there are so many pitfalls that put the 7-step process at risk. We're fortunate that until recently, loss of the entire electrical system was unlikely to force an airplane down. Now that we've embraced performance advantages of modern electronics to control engines, there's a pressing need to craft an architecture with particular attention to step (3). This is relatively easy to do if the seven steps are dutifully observed . . . but it's easy to be distracted from the process if excited rhetoric borne out of misunderstanding dominates the tenor of the discussion. So while we "gather and understand knowledge" (become designers) we must be ready to calmly defuse excitement with lucid explanation of simple-ideas and how they become ingredients that go into recipes for success (become teachers). Bob . . .


    Message 8


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    Time: 10:53:25 AM PST US
    Subject: Re: Welding cable
    From: Sam Hoskins <sam.hoskins@gmail.com>
    I was at my local True-Value hardware store, this morning, and they had the 4AWG inner jacketed stuff. I didn't look for the brand name, though. Sam On Sat, Sep 26, 2009 at 12:13 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com> > > At 09:45 AM 9/26/2009, you wrote: > >> Where can you find the anchor brand cable? Any weblinks/supply you can >> point to. >> Thanks >> Chris >> RV-10 >> > > A local welding supply store will offer Anchor or > a suitable equivalent. Some mention was made of > a "200A inverter cable" from Harbor Freight. While > these wires will probably have enough finely stranded > copper for the task, the question to be asked deals > with temperature characteristics and ruggedness of > the INSULATION. Welding cable produced to an ATSM > specification (as are most if not all American > products) will do the job for you . . . > > I searched for Anchor outlets but without success > after 20 minutes or so . . . however, the storefront > where I purchased the pictured sample was offering > Anchor brand cable at the time I bought it. That > was several years ago. > > Shop around locally first . . . > > > Bob . . . > > --------------------------------------- > ( . . . a long habit of not thinking ) > ( a thing wrong, gives it a superficial ) > ( appearance of being right . . . ) > ( ) > ( -Thomas Paine 1776- ) > --------------------------------------- > >


    Message 9


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    Time: 11:14:46 AM PST US
    From: halbenjamin@optonline.net
    Subject: Re: Welding cable
    Hi Bob, West Marine carries ANCOR brand battery cable. I don't know if it's any good. Just another piece of intel to muck things up. Hal Benjamin RV4 Long Island, NY ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Welding cable > III" > > At 09:45 AM 9/26/2009, you wrote: > >Where can you find the anchor brand cable? Any weblinks/supply > you > >can point to. > >Thanks > >Chris > >RV-10 > > A local welding supply store will offer Anchor or > a suitable equivalent. Some mention was made of > a "200A inverter cable" from Harbor Freight. While > these wires will probably have enough finely stranded > copper for the task, the question to be asked deals > with temperature characteristics and ruggedness of > the INSULATION. Welding cable produced to an ATSM > specification (as are most if not all American > products) will do the job for you . . . > > I searched for Anchor outlets but without success > after 20 minutes or so . . . however, the storefront > where I purchased the pictured sample was offering > Anchor brand cable at the time I bought it. That > was several years ago. > > Shop around locally first . . . > > > Bob . . . > > --------------------------------------- > ( . . . a long habit of not thinking ) > ( a thing wrong, gives it a superficial ) > ( appearance of being right . . . ) > ( ) > ( -Thomas Paine 1776- ) > --------------------------------------- > > > > > > >


    Message 10


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    Time: 11:27:52 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Hired wire-slingers
    >>##PS: Again this was given to me (after I paid big money to have the panel >>built), but I have access to the avionics that I need via an essential >>avionics bus so I have been living very happily with what he provided >>because I understand the system. The task of selecting a panel builder is two-fold. Unfortunately, features that drive most buy-decisions are appearance (craftsmanship), and experience (built a lot of panels). The the seven-step process I described earlier goes to the MOST important component of the buy-decision process . . . and is seldom offered by some of the most skilled builders. This is why the most successful airplane companies had good engineers that teamed with equally good craftsmen that were both free to continuously improve upon the best we know how to do. I always had a excellent relationship with the folks in the factory. I hold their skills in high regard . . . I've worked on those lines too. But corporate management is moving from self-serving entrepreneurs to stockholder-serving bankers. Product quality and capability is being wrenched from the control of designers and craftsmen and replaced with process and control dictates (ISO, FAR, EPA, etc). The result is predictable and inevitable. The best we know how to do is no longer represented by the folks who understood and built airplanes most of us learned to fly in. The best we know how to do is now in your basements and garages. Fortunately, there are many skilled craftsmen from the TC aircraft world who are supporting OBAM aircraft . . . but their skills and understanding as designers are carry-overs from their experience in the TC aircraft world. Great amounts of money CAN buy great amounts of mediocre work product. This is avoided when a team of artful designers AND craftsmen filter the activity through the Seven Steps. You are all program managers now . . . managers who have to design, craft, do make-buy decisions and ultimately climb into and fly the work product. While "caveat emptor" was mostly applied to the exchange of real estate, it's no less applicable here. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------


    Message 11


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    Time: 12:16:26 PM PST US
    From: <bakerocb@cox.net>
    Subject: Mounting BATT/START Relays
    9/26/2009 Hello Mike, You wrote: "........ this does not seem like a big deal to me as they are fairly long lasting devices."** I began my real plane aviation career as a US Navy airplane mechanic some 59 years ago. Since then I have spent thousands of hours working on airplanes, acquired an A&P rating, a Master's Degree in Aeronautical Engineering, built my own airplane, and flown several thousand hours. I had plenty of opportunity during that time to confront many maintainability issues. These issues come in many different forms, but one of the most important ones is accessibility -- if you can't access a part you can't fix it, adjust it, or replace it. It is very easy in the early stages of building a homebuilt to significantly underestimate the effort that will be required to access a part when the airplane is completed. I want you to envision your airplane completed and someone someday attempting to remove and replace one of the contactors which is held in place by through bolts also holding the other contactor in place on the other side of the firewall. It will require a wrench simultaneously on both the bolt head and the bolt nut. This means that two people will be required. One of those persons must dive down under the instrument panel -- not always an easy task (take it from an old man). What frequently happens when building the airplane is that one is able to use both hands on the part being worked on. When diving down under the instrument panel sometimes only one hand can reach the part. Realize also that some fairly heavy guage wires must be disconnected. Then on reinstall both contactors must be in alignment for the holding bolts to go through and wires must be reconnected. Mounting the contactors with anchor nuts can turn this into a one man job and reduce the time and effort significantly. 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." **PS: I am aware locally of three that have failed just in the last few years. ============================================= Time: 07:13:11 AM PST US Subject: AeroElectric-List: Mounting BATT/START Relays From: "rvg8tor" <rvg8tor@comcast.net> My battery will be just aft of the firewall so the battery relay will be mounted on the aft side of the firewall, the start relay will be just opposite on the forward side of the firewall. I see some who install plate nuts to mount these relays individually, 4 nuts + 4 bolts+4 holes in the firewall. The holes on the two relays work out so that one could just use 2 bolts and two normal nuts (not anchor nuts) and mount the two relays through common holes in the firewall. The only drawback I can see is that if one or the other needs to be replaced then both you can't remove one without disturbing the other, this does not seem like a big deal to me as they are fairly long lasting devices. Can anyone see why my idea is a bad one? I though of heat transfer from the hot side of the firewall, but bolts into nut plates would do that to some degree, and all of the relays could be mounted forward of the firewall like many factory airplanes have them. -------- Mike &quot;Nemo&quot; Elliott RV-8A QB (Fuselage)


    Message 12


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    Time: 12:24:12 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Welding cable
    At 01:00 PM 9/26/2009, you wrote: >Hi Bob, > >West Marine carries ANCOR brand battery cable. I don't know if it's >any good. Just another piece of intel to muck things up. > Thanks for the heads-up. I checked a portion of their offerings at: http://tinyurl.com/ycmabhn It's not clear to me that this is the same "Anchor" cable company. The material illustrated has tinned conductors while welding cable does not. Further, their prices (before shipping I presume) are pretty breathtaking. Higher than 22759 stuff from Aircraft Spruce! It seems that 'Anchor' is an exceedingly popular name for various brands/businesses. Makes it difficult to find 'the one' . . . Here's one good hit http://tinyurl.com/ydjdlr2 assuming you can use 500' of 4awg. This stuff is about $1.50/ft before shipping. This is how your welding supply store would buy it and sell it for $2.25/ft or so . . . It appears that the folks we're looking for offer a huge selection of electric and wire-welding parts and tools of which welding cable is only a small fraction of their catalog. Given this penetration into the welding supplies market, it's quite likely that local stores will know all about them. If anyone finds the mother website for Anchor brand welding products, I'd appreciate hearing about it. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------


    Message 13


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    Time: 03:23:54 PM PST US
    Subject: Re: Mounting BATT/START Relays
    From: "rvg8tor" <rvg8tor@comcast.net>
    BAKEROCB, All very good points. I do try to look at future maintenance when I am building my airplane. One of the reasons I am putting my battery just aft of the firewall is I will have easy access to it via the front baggage area for charging or jumping if it goes dead, it is also a more hospitable environment for the battery. I can get to both sides of the bolts holding the relays because the front baggage door gives access. The only limiting factor I have now made for myself is if the battery relay is the only thing I needed to replace then I would not have to remove the cowl if I had used nut plates. My thought at this point is I can always go that route in the future, for now I like the fact that I have two less holes in the firewall. See my log for pictures of the completed installation, done yesterday. http://www.mykitlog.com/users/display_log.php?user=rvg8tor&project=403&category=0&log=88927&row=1 -------- Mike &quot;Nemo&quot; Elliott RV-8A QB (Fuselage) Read this topic online here: http://forums.matronics.com/viewtopic.php?p=265145#265145


    Message 14


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    Time: 04:26:47 PM PST US
    From: "Chris" <toaster73@embarqmail.com>
    Subject: Welding cable
    Well I guess you see why I asked, I spent some time googling and didn't find much whioch actually called out the epdm insulation. Guess I should have mentioned that. I did find this place and I sent an email to ask what brand it is they carry, hopefully they will respond Monday and I'll report back. Its finding that EPDM insulation that seems tricky, I had some stuff locally but it had a paper inner liner and I didn't find the outer stuff to be very tough, it seemed easy to nick and penetrate. http://www.wesbellwireandcable.com/Welding.html -Chris RV-10 From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Saturday, September 26, 2009 3:20 PM Subject: Re: RE: AeroElectric-List: Welding cable At 01:00 PM 9/26/2009, you wrote: Hi Bob, West Marine carries ANCOR brand battery cable. I don't know if it's any good. Just another piece of intel to muck things up. Thanks for the heads-up. I checked a portion of their offerings at: http://tinyurl.com/ycmabhn It's not clear to me that this is the same "Anchor" cable company. The material illustrated has tinned conductors while welding cable does not. Further, their prices (before shipping I presume) are pretty breathtaking. Higher than 22759 stuff from Aircraft Spruce! It seems that 'Anchor' is an exceedingly popular name for various brands/businesses. Makes it difficult to find 'the one' . . . Here's one good hit http://tinyurl.com/ydjdlr2 assuming you can use 500' of 4awg. This stuff is about $1.50/ft before shipping. This is how your welding supply store would buy it and sell it for $2.25/ft or so . . . It appears that the folks we're looking for offer a huge selection of electric and wire-welding parts and tools of which welding cable is only a small fraction of their catalog. Given this penetration into the welding supplies market, it's quite likely that local stores will know all about them. If anyone finds the mother website for Anchor brand welding products, I'd appreciate hearing about it. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------




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