Thats what I did. 10-3, 30A for my 220 TS and 12-3, 20A for my 220 DC. I
then added a few 110 convienience outlets to the DC circuit. I only worry a
bit about tripping my breaker if I move my compressor from its dedicated
110v 20A circuit, for convienience sake ;) , to one of the outlets on my DC
circuit. If the compressor kicks in while DC is on..... has happened once
but never tripped the breaker yet! I'm sure if both were starting at same
time that sucker would blow pretty quick.
Breakers tend to be heat-based, so a short pulse of over-current is
usually acceptable. The purpose of breakers is to protect the wiring
up to the outlet, not to protect the device plugged into it, so they
try to simulate how much heat the wiring is generating and shut off
the current before the wire's insulation breaks down.
The only time I've seen a breaker blow "pretty quick" was when it was
Breakers are designed with various trip delay curves to suit the
intended application. There's a good overview at
http://tinyurl.com/cffxx . Looking at the curve in Fig 1 of that
article, that particular breaker described looks like it trips in
about 20 seconds for a 2x overload, about 4 seconds for a 5x
overload, and above a 10x overload, the trip time is down in the
Pedantic mistakes in that picture:
* The two mains in the breaker box aren't wired that way. They
zig-zag back and forth so that vertically adjacent breakers are
always on separate mains.
* 24v circuits are always wired with a single ganged breaker that uses
two vertically adjacent slots; it is wrong to wire one 240v outlet to
two separate breakers.
* It is wrong to tie both ground and neutral to the same tie block on
the breaker panel, even when the two blocks are tied together in the
* The three-hole 240v outlet should have the third hole tied to
ground, not neutral. Only four-hole 240v outlets use neutral.
* The circuit is grounded at two places (the transformer and the
neutral tie block). Only one ground tie-in is permitted per
building. The circuit should be grounded at a *ground* tie block,
with neutral tied to ground at one point (usually the main breaker
* The transformer is labelled "120V RMS" on the primary side, which is
wrong (the primary is usually 7200v or more), and the US standard is
240V not 120V. (The US, unlike Europe, provides a center tap for
lower voltage devices, but the main voltage is the same).
Worse than nitpicking, actually. What makes you think that, for instance,
the mere proximity of the "120V rms" to the primary means it references the
primary? It's a case of space, and has no pointer.
It's not meant to instruct you how to wire, they refer you to the NEC for
Now go have a nice warm milk to counteract that nervous caffeine energy.
He did say pedantic, and although I can understand that the drawing takes
liberties for the sake of readability (like not having bus slots zig-zag)
putting a neutral connection on that 240V outlet is just wrong.
Leif Thorvaldson (in firstname.lastname@example.org) said:
| ====>I would still like to know if the cat in the black box is
| alive or dead? *TIC*
DeSoto, Iowa USA
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.