[RE-wrenches] AC breakers used in DC applications

Mon May 17 03:22:51 PDT 2010

The UL listing is only good for 12 or 24 volts, the manufacturer listing
carries no weight if the defecation hits the rotary oscillator.

UL is the one that counts.

If you're using an MPPT controller unless the panels are wired as single
panels you can't use the QO breakers. I have always run them in pairs, in
this area we can't run them in a series of 3, too cold.

As Robin told me once when I thought that I could, "Move to Hawaii and do it
there" 

Outback and Midnites's gear has changed the industry. Many thanks to them.

Later,

Bob 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Sunday, May 16, 2010 6:31 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] AC breakers used in DC applications

My understanding was that the din mountable QOU breakers were rated to 125
vDC, and are internally the same as the QO. The difference was the
connectors, and the mounting method.

I've used the QOUs reliably at 120 v nom on an EV, (but don't try this at
home, kids)

We still use the QOs sometimes based on cost and availability, but I don't
use them on anything over 24 v nominal anymore. 

They were handiest in that one breaker line could cover AC and low volt DC.

With MPPT high voltage arrays, and some of Midnite Solar's new products
(Mini DC & Baby DC boxes), though, we've found less and less of a place for
the venerable QO line.

R. Walters

ray at solarray.com

Solar Engineer

On May 16, 2010, at 2:25 PM, Kurt Albershardt wrote:

Square-D tells me they have tested the breakers to a higher voltage (can't
recall now whether it was 80V or 125 VDC) but the listing is indeed for 48
Volts.  24V battery systems are useful for a lot of applications, but the
unfortunate lack of a 5A breaker means we can not use them to derive a Class
2 supply, which would make them about 10x as useful to me.

On May 15, 2010, at 9:22 , jay peltz wrote:

Hi Rebekah,

The 48v is a max rating not a nominal rating.

So yes only good for 12 and 24v systems.

However with CBI breakers I don't understand why the need for QO for DC
anymore?

jay

peltz power

On May 15, 2010, at 6:28 AM, Rebekah Hren wrote:

Hi,

One thing to be clear about is whether these are listed for "48 volt
systems," or for max 48 volts?

I was under the impression that they were max 48 volts, meaning you really
shouldn't use them on a system >24volts nominal.

Rebekah Hren

North Carolina

http://thecarbonfreehome.com/

--- On Sat, 5/15/10, Kurt Albershardt <info at es-ee.com> wrote:

From: Kurt Albershardt <info at es-ee.com>
Subject: Re: [RE-wrenches] AC breakers used in DC applications
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Saturday, May 15, 2010, 12:59 AM

The Square-D catalogs are marginally clear on which breakers are listed for
DC and for what voltages, but when I tried to select an appropriate load
center for a DC application earlier this year I quickly ran into a number of
conflicts in their catalogs.  Here is the response from Schneider tech
support (Case# 4845778 on 1/19/10 in case anyone runs into problems with an
inspector):

The load center catalog numbers listed below are UL LISTED, File E6294, for
use on 48 V dc systems. The load centers listed ARE NOT MARKED for use on
this voltage system, however are suitable for the application. QO branch
breakers, 10-70 ampere (1 and 2 pole) are also UL LISTED for use on 48V dc
systems. Short circuit current rating is limited to 5,000 amperes when used
on 48V dc.
QO24L70F, S or RB QO612L100F, S, DF, DS, DFCU, DSCU, RB, TRB or RBCU
QO816L100F, S, DF, DS, DFCU, DSCU, RB or RBCU
QO112L125G or QO11224L125G QO116L125G QO11624L125G QO120L125G QO12024L125G
QO124L125G or QO12030L150G QO124L150G QO130L150G or QO112L200G or QO130L200G
or QO13040L200G QO142L225G or
GRB or GRB
or GRB
GRB

GRB GRB GRB or GRB QO142L225GRB

I can email the PDF to anyone who needs a copy.

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