Solid core wire - ok for heaters?

Express, Liverpool, Rocket, Dirty Little Monster, etc.

Moderators: pompeiisneaks, Colossal

User avatar
xtian
Posts: 6990
Joined: Mon Apr 19, 2010 8:15 pm
Location: NorCal
Contact:

Re: Solid core wire - ok for heaters?

Post by xtian »

OK! Agree. Thanks for knocking this bit of basic electronics back into my noggin.
I build and repair tube amps. http://amps.monkeymatic.com
User avatar
didit
Posts: 976
Joined: Thu Sep 25, 2008 3:37 pm
Location: Canada

Re: Solid core wire - ok for heaters?

Post by didit »

While always wiring in parallel, no requirement that this is one long string. Same wire size as your transformer manufacturer has coming out on the filament secondary is best gauge for first few segments.

Best .. Ian
User avatar
Ken Moon
Posts: 610
Joined: Tue May 08, 2007 2:41 pm
Location: Denver

Re: Solid core wire - ok for heaters?

Post by Ken Moon »

See if you can get this spreadsheet to work for you - you have to enable editing and macros - but this is by far the best calculator I've seen for ampacity in single wires and bundles in electronic equipment. Much more sophisticated and accurate than the electrician's tables that are based solely on circular mils.

This was developed using NASA's Mil-STD-975 for space and military aircraft applications, so obviously it's conservative, but the bottom line is that 22 ga wire is fine for all signal wires and 20 ga for heaters - although going to 18 ga for the power tube heaters provides a healthy safety margin, and is not a problem wiring if you use sockets such as the Belton micalex 8-pin sockets for your power tubes, which have nice big dual solder holes.

I've included a screenshot with typical values in case I can't figure out how to share the xls file.

https://1drv.ms/x/s!Ag-TpoqAJ9n8iTHEjG08a9rPwXS_

https://1drv.ms/i/s!Ag-TpoqAJ9n8iTBbsx-UnIEBYG-m
Post Reply