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 Post subject: Is High Voltage Wire Needed?
PostPosted: Feb Sun 10, 2019 9:28 pm 
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Location: Cedar Rapids, Iowa
I think I know the answer to this but want to be sure before I go tearing into my nearly completed radio. My first attempt at a restoration a couple of years ago was a Philco 47-1230 that belonged to my grandparents. After doing a fair amount of work on it I decided to set it aside and get more experience on less complex radios. I've recently returned to working on it and it is very nearly complete. But, 2 years ago I was ignorant about wire voltage ratings and used some wire I bought at the auto parts store to replace some of the wires, including some high voltage wires.

So now I'm planning to go back and replace those with some 600v wire. Is it necessary? I'm pretty sure it's a good idea, but I replaced the wires on the high voltage secondary of the power transformer and I don't look forward to removing it again.

Thanks!

Rich


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Sun 10, 2019 10:30 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
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I don't know what kind of wire you bought at the auto parts store. But I feel pretty safe to say that wire is wire at these frequencies, as long as the guage of the new wire isn't smaller than what was there.


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Sun 10, 2019 10:39 pm 
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You might try to find out from the auto parts store, if they have some published Voltage rating. I would surely think they would, perhaps on line. You might be lucky and find their voltage rating for the wire you bought is sufficient for your application.

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Sun 10, 2019 10:50 pm 
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Automotive wire normally has a low voltage rating, like less than 60v. The insulation on it is usually fairly thick PVC for durability in the automotive environment, but that is not enough to give it a higher rating. My thoughts are that it is marketed as a low voltage wire because it has not been thru the expense of UL Labs testing. UL will normally test wire at many times the voltage rating- like a couple of thousand volts for 600v wire. Temperature and other factors play a part in the rating. Don't think that as the voltage passes the rated voltage that the wire will start arcing thru the insulation. There is a huge safety factor built into that rating. I usually don't get too hung up on the voltage rating of wire, especially after seeing the original wire that I pull out of these sets. I use 300v wire or unrated wire for nearly everything including B+. The Radiodaze thin profile cloth covered wire is not rated and it is my "go to" wire when I need cloth covering.

But to answer your question, yes, it might be a good idea to change it.


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 12:08 am 
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Joined: May Tue 30, 2006 4:46 pm
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Location: Santa Rosa, CA
UL tests wire to Standard 758.

http://www.highflexcables.com/UL758-2000REV.pdf

300 V rated "appliance wire" would be tested at 1500 V or 2500 V AC. See page 48. Interesting though that some sizes of 600V wire are tested only to 2000V.

Rich


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 12:38 am 
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well i worked at a auto parts store for many years and never knew that it made a difference so many many radios i repaired have auto wire in them --was it correct? i doubt it-- but as far as i know it works--

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 12:49 am 
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I'm constantly amazed by folks who say
"I didn't do it right, and it works, so apparently you don't need to do it right."

Then some time later a noobie reads that thread and comes to the conclusion that he doesn't need to do it right, and it will still work.

Makes me wonder why I and other knowledgeable techs spend endless hours on ARF trying to teach proper repair practices to folks.

- Leigh

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 1:00 am 
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Leigh wrote:
I'm constantly amazed by folks who say
"I didn't do it right, and it works, so apparently you don't need to do it right."

Then some time later a noobie reads that thread and comes to the conclusion that he doesn't need to do it right, and it will still work.

Makes me wonder why I and other knowledgeable techs spend endless hours on ARF trying to teach proper repair practices to folks.

- Leigh


Exactly. If it's worth doing at all, it's worth doing right and that means researching and sourcing the proper parts and materials to make a safe and durable repair.

The only thing that automotive type wire is suited to is repairing vehicles with low voltage systems, such as 12 volts. One could also use it for low voltage wiring in filament circuits of transformer powered radios, but it isn't rated for higher voltages like AC line or B+, so why would anyone think it was OK to use it for that?

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 4:22 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Why would anyone think that carefully restoring a 70 year old
radio to working condition, and then assuming it is as safe to operate
in the original cabinet, without the final tests done by the factory is ok ?

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 4:26 am 
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Joined: Mar Thu 02, 2017 1:37 am
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Location: Cedar Rapids, Iowa
Ok, as I expected, I'm pretty well convinced that I should bite the bullet and replace the wires with good high voltage wires. I'm 63 years old and I can still remember my dad telling me that if something is worth doing, it's worth doing right ;) I'm not so concerned about the time and effort...I have plenty of both. I'm just concerned about doing more unsoldering/soldering on 72 year old terminals. But, I'm going to do it!

Thanks for all the input guys ;)

Rich


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 4:41 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 162
I never unsolder from terminals. That's a lesson hard learned from breaking off tube socket lugs and such. Now I just clipped off wires leaving a pigtail to solder to and shrink tube as needed.


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 6:52 am 
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Location: Northeast Florida
criageek wrote:
Ok, as I expected, I'm pretty well convinced that I should bite the bullet and replace the wires with good high voltage wires. I'm 63 years old and I can still remember my dad telling me that if something is worth doing, it's worth doing right ;) I'm not so concerned about the time and effort...I have plenty of both. I'm just concerned about doing more unsoldering/soldering on 72 year old terminals. But, I'm going to do it!

Thanks for all the input guys ;)

Rich


If you have desoldering braid, that helps a lot. Once the solder is gone from the lug, it's not too hard to unwrap the wire

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 4:21 pm 
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Location: Maryland 20709, USA
criageek wrote:
I'm just concerned about doing more unsoldering/soldering on 72 year old terminals.
Hi Rich,

I normally use a good solder sucker, like a full-size Solda-Pullt. Works fine.

- Leigh

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 5:41 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
If you follow along with schematics, you'll see that there are wires connected to many different voltages in old radios. In a radio with a power transformer like the Philco 47-1230, all of the tubes except the 5Y3 have parallel wired, 6.3 volt heaters. Ditto for the pilot lights. So no need for high voltage wire in those circuits. The cathodes, first grids (G1) and suppressor grids (G3) of all the tubes except the 5Y3 only have low voltage DC on them, so no need for HV wire there either. The antenna transformer connections and the volume and tone control circuits are likewise at low voltage.

On the other hand, anything associated with a plate, screen grid (G2), or the 5Y3 could have enough voltage on it to break down the insulation on low voltage wire. And anything associated with the AC line, like the on/off switch wiring, calls for wire rated for line voltages or higher.

Point being, you might not need to rip out and replace all your previous work, only the wires that actually carry higher voltages.

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 6:01 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4464
Location: Charleston, W.Va.
Hi criageek,
No one likes doing something over again, but sometimes it is necessary. As an alternative to actually replacing your previously-installed wire, assuming it it is of the correct wire gauge, you might want to consider lifting only one end of each wire and slipping some properly-rated heat shrink tubing over the existing insulation. Much easier than replacing the entire wire, and will give the same results.

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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Mon 11, 2019 11:39 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 3547
Location: Florida
Chris108 wrote:
If you follow along with schematics, you'll see that there are wires connected to many different voltages in old radios. In a radio with a power transformer like the Philco 47-1230, all of the tubes except the 5Y3 have parallel wired, 6.3 volt heaters. Ditto for the pilot lights. So no need for high voltage wire in those circuits. The cathodes, first grids (G1) and suppressor grids (G3) of all the tubes except the 5Y3 only have low voltage DC on them, so no need for HV wire there either. The antenna transformer connections and the volume and tone control circuits are likewise at low voltage.

On the other hand, anything associated with a plate, screen grid (G2), or the 5Y3 could have enough voltage on it to break down the insulation on low voltage wire. And anything associated with the AC line, like the on/off switch wiring, calls for wire rated for line voltages or higher.

Point being, you might not need to rip out and replace all your previous work, only the wires that actually carry higher voltages.


Ever see any data on what the radio manufacturers actually used?

RRM


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Tue 12, 2019 3:17 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 10907
Location: Powell River BC Canada
Quote:

Ever see any data on what the radio manufacturers actually used?

RRM

Here is some radio wire stuff. I wasn't born when the neco table was in use,

I dealt with the other data, when we sought approval on certain products we sold.
Attachment:
Radio wires 1941.jpg
Radio wires 1941.jpg [ 215.75 KiB | Viewed 252 times ]
Attachment:
Radio Wire peek back  r.jpg
Radio Wire peek back r.jpg [ 181.84 KiB | Viewed 252 times ]

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Amateur Radio Literacy Club. May we help you read better.
Steve Dow
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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Tue 12, 2019 3:13 pm 
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Joined: Mar Thu 02, 2017 1:37 am
Posts: 344
Location: Cedar Rapids, Iowa
Thanks again guys for all the feedback...I appreciate it! I've completed the re-rewiring and it wasn't nearly as bad as I expected. There were only about 12 - 15 wires involved, most of those on the power transformer. I thought I was going to have to remove the power transformer to get to the splices I made previously, but they were easily accessible after lifting the output transformer out of the way. My only real concern is one terminal on the 5Y3 rectifier tube...it doesn't seem too stable. I THINK it's solid enough to move on but I still have concerns. I'd rather not replace the socket if I don't have to.

Rich


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Tue 12, 2019 4:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 33990
Location: Maryland 20709, USA
Well done, Rich.

- Leigh

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http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: Is High Voltage Wire Needed?
PostPosted: Feb Wed 13, 2019 3:30 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 162
criageek wrote:
Thanks again guys for all the feedback...I appreciate it! I've completed the re-rewiring and it wasn't nearly as bad as I expected. There were only about 12 - 15 wires involved, most of those on the power transformer. I thought I was going to have to remove the power transformer to get to the splices I made previously, but they were easily accessible after lifting the output transformer out of the way. My only real concern is one terminal on the 5Y3 rectifier tube...it doesn't seem too stable. I THINK it's solid enough to move on but I still have concerns. I'd rather not replace the socket if I don't have to.

Rich

Like I said, and for just this reason. Just clip the wire leaving a pigtail to splice to and use shrink tubing. Having learned that lesson I decided there's NO excuse for ruining a tub socket or any other tie point.


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