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JayJay (64.12.103.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 04, 2001 - 4:39 pm: | |
On Aug.8th I answered a post from Nick Russel, about wiring procedures for his MCI-8. I stated he could mix voltages in a single conduit. The next day Mr. George Myers said it was not permissible and that I was incorrect. For those of you with a copy of the National Electrical Code turn to : Article 300-2 (c),(1) It states: Conductors of circuits rated 600 volts, nominal, or less, alternating-current circuits, and direct-current circuits shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway. All nonshielded conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway. IN ADDITION Article 760-26 (a) states: ClassI and nonpower-limited fire alarm curcuits shall be permitted to occupy the same cable, enclosure, or raceway without regard to whether the individual circuits are alternating current or direct current provided all circuits are insulated for the maximum voltage of any conductor in the enclosue or raceway. IN ADDITION: Mr. George Myers also states to Fast Fred, that he should use all Boat Type boxes, wiring, fittings etc. No Article of the NEC allows the use of Nautical Type Wiring Systems in a motor home or any other type of residence. There are many pertinent Articles to adhere to in the U.S. Building Codes. Plumbing, Electrical, etc. In order to have a safe, insurable, saleable coach, you should research them all. I have over thirty years experience at the electrical trade, have held an Electrical Inspectors Certificate, and am cetified for Fire Alarm Installation/Inspection in the State of Ohio, I also hold a Master Electricians License in the State of Florida. Cheers...JJ |
JayJay (64.12.103.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 04, 2001 - 4:43 pm: | |
Date of original post is Aug. 28th, not 8th as it shows in my post. Cheers...JJ |
David Anderson (168.215.176.116)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 04, 2001 - 10:17 pm: | |
Hey JJ: Thanks for the post. About 4 months ago I posted a request for some ideas about a fire suppression system in my genset box. I really didn't get any good ideas. I would like to put a sensor in the box like a sprinkler head attached to a bottle extinguisher positioned outside the box. In case of fire I would like the sensor to open the bottle and spray the genset to squelch the fire. Do you have any opinion or ideas as to how to fabricate such a system? Post it here if you do. Thanks, David Anderson |
Jim Wilke (199.181.167.68)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 05, 2001 - 8:35 am: | |
Hi J.J.,
Thanks for the reference to the NEC rule.
I think what George Myers meant was that it is bad practice to put A.C. & D.C. in the same conduit, box, etc. If so, then you are both right!
While I am not a licensed electrician, I have been working on boats, vehicles, standby generator sets, etc. for about 30 years. I have seen people shocked from high voltage being present in low voltage and D.C. systems that had insulation faults and were run together with the high voltage A.C. systems. Many of these incidents happened because the person thought the low volt D.C. wires had only 12 volts in them as they should have had.
I've seen lots of low voltage equipment damaged from this crossing over of higher voltage.
I have seen stray signals induced in low voltage electronic engine governor systems where the magnetic pick up wire was bundled with the 240V AC genset output leads. (This caused the engine to change RPMs when the genset was loaded. The more load, the greater the deviation.)
All sorts of annoying noise, etc. often occurs when TV, stereo & 'phone wires run too close to A.C. wires for any distance. Most of the time, these problems are very hard to isolate because often they occur within a certain set of circumstances. In the case of the engine governor, at least five service calls were made and all of the three governor components were replaced before it was noticed that the sensor wiring had been run in the A.C. wiring bundle.
So it may be legal, but most technicians will strongly advise against the practice.
Jim-Bob |
George Myers (12.85.14.89)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 05, 2001 - 10:29 am: | |
Jayjay correctly quotes Article 300-3 (c)(1) not 300-2 (c)(1). However, Article 551-10 (c)(3), that applies directly to recreational vehicles, states "Battery and dc circuits shall be physically separated by at least 1/2 in. gap or other approved means from circuits of a different power source...." This is a little hard to do in a conduit.
As far as wires with signals, such as TV, phone, etc. I knew that I had read that they too could not be included with 120-VAC, but could not find it in the code. I went back to the 1971 code and found it in Article 300-3 (f); however, this paragraph is no longer in the code, and I could not find the subject elsewhere. This is one of the problems of getting old. You learn this stuff and think you know it, and they change the rules behind your back.
In general, it is a bad idea to have any wire carrying information run along with a high current AC line. The magnetic field generated by the AC current will create a hum on the signal wire. The line to the remote control panel on my Trace 4024 picks up enough from the parallel 120-volt line to scramble its readings, and they are in separate plastic conduits a couple inches apart.
The point on using marine components, in my previous post, was that: If you must wire your coach in contempt to the NEC claiming that you are doing it to "Higher" marine standards, be sure you do in fact wire it to those standards, and not make it a kluge of parts selected at random. This means that you must get, read, understand, and follow the Coast Guard manuals.
See you at the Bus Conversion Convention. We are about to depart and will be off line for a while.
George Myers |
JayJay (205.188.200.56)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 05, 2001 - 1:17 pm: | |
The difference between intentions and deed are often vast, and higher standard or not... you cannot legally use boat type wiring systems in a motorhome. You can use barbed-wire, and no one cans stop you, BUT, could you sleep well in it? How will you defend your actions in Court after you have sold it, and someone has been injured in it. A properly shielded piece of equipment will not pick up stray harmonics. Cheers...JJ |
Steven Gibbs (12.148.43.8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 05, 2001 - 3:40 pm: | |
David,
It looks like your question was missed. The suppression system you seek is available "off-the-shelf" from marine sources such as West Marine for use in engine compartments.
They usually come with a circuit for a light or, even better, the ability to shutdown your generator upon discharge. This would be very important to prevent the agent from being forced out of the compartment by the cooling fan.
I had a unit like this in my boat that was Halon but the new systems use replacement agents like FM200. |
Jim Wilke (199.181.167.68)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 06, 2001 - 8:51 am: | |
Jay Jay,
I would have e-mailed you directly but you are not set up for a reply when I click on your header bar.
RE: your previous post.
True, a properly shielded device SHOULD NOT pick up harmonics. BUT...."properly shielded" is based upon the engineer's ability to predict what forces can be reasonably expected to be present in the device's installed environment. Like everything else, engineering employs compromises, hopefully none of which cause injury. Sometimes they just overlook something or do not calculate potential effects correctly. A lot of those effects are theoretical until the right set of circumstances occur.
Every product recall is due to an engineer or team of engineers miscalculating the stresses or outside influences placed on the item he/they engineered.
I can tell you that in the case of the governor malfunction, the signal wire was definitely the specified wire with outer braided shield properly grounded at both ends. But there were so many amps passing through the output leads (which were tie-wrapped to the signal wire) that stray current was caused despite the shielding. When the wires were separated by 3", the problem disappeared for good.
I'm just saying it CAN and does happen, and suggesting good common sense, cheap ways to prevent such headaches.
Jim-Bob |
JayJay (205.188.200.44)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 06, 2001 - 11:31 am: | |
I didn't miss the fire suppression post, I've not had time to reply.You will have to use either infrared or temperature sensitive detectors (both?)since the cheaper ionic types won't work in that environment. Check with our local distributor for material, and use his advice. As suggested, a pre-engineered system would probably be superior, and cheaper. Since it is not habitable space, I would opt for CO2, rather than the messier (after discharge) dry chemical. Be sure to provide coverage for the fuel supply also. Maybe a check valve in the fuel line to stop fire spread, if the tank is remote from the genset.I even installed a 12V DC pump (multiple switches for discharge) and sprinkler heads in my living quarters. Nothing exotic, just 25 GPM/40 PSI, and some lawn hose, wide coverage sprinkler nozzles. I used 1/2 in. cpvc plumbing. Someone voiced the opinion that it might melt. Yup! Sure would, but thats exactly where you would want the water!!! No e-mail profile because I retired at 55 last year, and have been on the road since then. In the last ten months I've had the my GM 4905 in twenty states, and put ten thousand miles on it. ( for the next six weeks try emjjr45@aol.com) HTH, and Cheers...JJ |
Scott Whitney (63.151.68.130)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 06, 2001 - 1:44 pm: | |
Hi JJ,
Sort of off topic, but have you looked into a Web based e-mail account like Hotmail? You can check e-mail from anywhere that has web access and you can keep the same address year after year. Just a thought.
Scott |
Mallie (208.165.105.105)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 09, 2001 - 10:36 am: | |
Hi JJ,,, You may know the NEC, but George has done more research on RV codes than anyone I know. George has stated repeatedly that boat cable is not approved for RVs use. But several major converters use it, Custom Coach is one of them. They don't seem too worried about the legal issues. A court is not going to slap you unless the product was the cause of the problem, and it ain't gonna be if it is properly installed.
And regardless of codes, as Jim has pointed out, there is common sense.
Personally I do not think it makes one iota of difference, which wire you use, Romax, stranded in conduit, boat cable, extension cords, etc, if it is properly installed.
I would probably stay away from the barbed wire tho. That could be sticky to handle.
Mallie |
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