Hook Up Wire Voltage Rating (300v?)

Charlie Wilson · Post by **Charlie Wilson** » Tue May 12, 2015 7:18 pm

Hello All, well after pretty much finishing my Low Plate Classic I have decided to completely rewire it with PVC wire(yeah I know I am Crazy). It looks to me that Dumble used 300v wire everywhere in his amps. At least in the photos and ones in person I have seen. I am not brave enough to use 300v wire on the power tube screens or power tube plates but I am thinking entire preamp(except plate supply). Although the PI plates sometimes creep just over 300v. My understanding is that the cloth wire used in Fender amps was rated to 300v. Any thoughts on this or safety issues I may have overlooked. One thing that does concern me is that if you remove the preamp tubes there is more than 300v sitting on the preamp plate leads that are laying on the chassis. Why I am I doing this? Because I really want to hear if there is a difference in sound between PVC and Teflon.
CW

martin manning · Post by **martin manning** » Tue May 12, 2015 9:26 pm

Just get this stuff and you won't have to fret over it.
http://valvestorm.com/Products/Wire
The voltage rating, that is. You can still fret over the sound of this 600V vinyl wire vs. that 300V vinyl wire.

Charlie Wilson · Post by **Charlie Wilson** » Tue May 12, 2015 9:54 pm

Thanks Martin. I think that is the same stuff I got from Metro Amps a few years ago. I like it but it is pretty flexible. The thing is I already purchased a bunch of solid PVC 300v and some 600v from McMaster Carr. I guess if I have a question it would be did Dumble indeed use 300v wire in his amps and is the 300v rating conservative enough that exceeding it slightly would be a problem? My understanding of UL standards is that there is a considerable safety margin. It seems to me that 300v wire was the standard in amps from the 50s and sixties.
CW

martin manning · Post by **martin manning** » Wed May 13, 2015 12:55 am

Yes, I believe it is the same wire that Metro had on their site. I'm a big fan. It is flexible, but it will stay put, and it will work fine for the whole amp. You'd be okay using 300V wire if you do as proposed and keep it out of the HV power supply and all of the plate and screen circuits.

Charlie Wilson · Post by **Charlie Wilson** » Wed May 13, 2015 5:28 pm

Thanks again Martin. I am a bit of a worrier, so I think I will go with your recommendation and use the 600v topcoat wire. Maybe some of the through holes on the preamp board will need to be widened but that is easy enough.
CW

Mark · Post by **Mark** » Wed May 13, 2015 7:21 pm

I've wondered whether the material the insulation is made of is of no consequence but the thickness and it's proximity to earth (for example) is actually the issue?

Perhaps the capacitive coupling is the issue people talk of and not the insulation material?

I've used teflon and PVC, I like the durability of the teflon, but the PVC bends easy and stays where it is put which is great for those Trainwreck and Dumble builds.

Charlie Wilson · Post by **Charlie Wilson** » Wed May 13, 2015 7:55 pm

Yeah Mark I don't know what if any difference there is. I have read all of the theories and many people think Teflon sounds brighter than PVC and some say they hear no difference at all. I think I have pretty good ears and I just want to see if I can hear for myself and put this issue to rest in my own mind.
CW

John_P_WI · Post by **John_P_WI** » Wed May 13, 2015 7:58 pm

Mark wrote: Perhaps the capacitive coupling is the issue people talk of and not the insulation material?

Would that not only hold true for wires immediately adjacent to others or for wires flat against the chassis?

martin manning · Post by **martin manning** » Wed May 13, 2015 9:41 pm

Absolutely. PTFE has a dielectric constant about 2/3 that of PVC, so it would have a smaller capacitance between adjacent wires or a wire and the chassis (ground). PTFE insulation is usually thinner than PVC (half?) though, and that would make the capacitance larger. The magnitudes are small though, one or two pF per inch, I believe.

aflynt · Post by **aflynt** » Wed May 13, 2015 11:04 pm

I've been using cloth covered wire, and according to the chart below my amps sound like crap.

http://www.clippercontrols.com/pages/Di ... alues.html

Seriously, though:

DIELECTRIC CONTSTANTS
Cotton - 1.3-1.4
Teflon (PTFE) - 2
PVC - 3.4

-Aaron

roknroll · Post by **roknroll** » Sun May 17, 2015 11:57 am

[img

576]http://i967.photobucket.com/albums/ae15 ... lphaop.png[/img]

Charlie Wilson · Post by **Charlie Wilson** » Mon Nov 09, 2015 7:40 pm

Hello, I have been continuing to read up on hook up wire voltage rating. I have been seeing a lot of 300v wire in production amps from the 70s and 80s and most the wire I have seen in Dumble amps does not look like 600v. I found the attached link very interesting and makes sense to me. It would imply that 300v(RMS) wire can safetly handle at least 400vdc(working voltage).
http://cloud.samtec.com/NotesAndWhitePa ... 102007.pdf

CW

Structo · Post by **Structo** » Mon Nov 09, 2015 8:00 pm

I really like the teflon stranded wire.

Small diameter, silver plated, no melt insulation. (big one for me)
The silver also seems to make the solder flow better on connections.

For example, 20ga PTFE coated wire can handle 11 Amps.

I use mainly 20ga throughout the amp.

Power tube heaters get 18ga, then 20ga for the preamp.

I find it lays down or holds shape pretty good.

Be wary of the low strand count teflon wire, it doesn't hold up well.

Charlie Wilson · Post by **Charlie Wilson** » Mon Nov 09, 2015 8:13 pm

Tom, I have used both Teflon and PVC and I prefer the PVC. I really hate stripping the Teflon especially the blue and green colored insulation. I don't like how microphonic it is and it sounds a bit more hi fi to my ears(I know not everyone agrees with this). I want to start using backing boards for the preamp board and the 600v PVC insulation is too thick. Plus I have a big box of style 1007 sitting under my bench.

My main concern with the 300v rated wire was the plate supply wires sitting on the chassis. Especially when there are no tubes in the sockets(400+VDC). In light of what I have learned about how they rate the wire I feel more comfortable with it now. I am going to use 600v wire for B+ from rectifier board, stand by wires, power tube screens and plates, and probably plate supply going from the power board to the preamp board. Having said all of that, there are some great sounding amps out there that have Teflon wire.
CW

Structo · Post by **Structo** » Mon Nov 09, 2015 8:28 pm

Yeah it can be difficult to strip without the right strippers.

I'm not sure I buy into the "sound of wire", especially on a guitar amp.

But you are right, build an amp as close to the designers choice of components as possible.

I have used the 300v wire from Radio Shack on a couple small amps.
No arcing or other indication that it was over spec'd.

Probably wasn't exposed to over 400v but to be safe, a higher voltage wire is
definitely recommended.

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Hook Up Wire Voltage Rating (300v?)

Hook Up Wire Voltage Rating (300v?)

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mojo tone has great wire

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