600 VDC switches [RE-wrenches]

[EH Roy]

Brad,

I remember that arcing problem, but don't remember the brand of disconnect
it occurred in.

Square D technical support tells me I don't have to wire two outside poles
in series to get a 600VDC rating on their HU361 - switching of one positive
through one pole is appropriate and covered by the UL listing. They are
still scratching their heads about how many positives can be switched in one
disconnect.

E. H. Roy
Solar Works, Inc.
64 Main Street
Montpelier, VT 05602
1-800-339-7804 ext. 306
ehroy at solar-works.com

-----Original Message-----
From: Brad Bassett [mailto:bsbassett at earthlink.net]
Sent: Wednesday, September 18, 2002 4:32 PM
To: RE-wrenches at topica.com
Subject: RE: 600 VDC switches [RE-wrenches]

Matt,

I believe that Sq D does not put the necessary jumper in at the factory
between the two poles to get the 600vDC rating. The lebelling on various
disconnects has sometimes been lacking also. Although GE has supplied
the jumper for many years, their labeling was confusing. It now appears
that they got the message and the labelling is clear and they call out
the difference between the single pole 250v DC rating and the two pole
break 600vDC rating. I don't know what the other mfg's do.

Back almost a decade ago, we had someone in the field installing our
first 600vDC array and used a single pole, which when opened sustained
an arc until they literally blew it out. In our subsequent conversations
with various disconnect engineers we learned that a single pole will
come close to breaking 600v and sometimes will depending on current etc.
But to be reliable and meet UL testing, breaking two poles is needed at
these voltages.

Brad


matthew tritt wrote:
> William,
>
> Your questions bring up some very interesting points. I did an install
> yesterday using a Sq D 3 pole breaker which has no jumper and no mention
> anywhere of a decreased rating. > > manufacturers achieve the 600 volt
> rating:  They use a 3 pole disconnectI'm going to check with the
> distributor and
> see if I can get an answer on the need to add a 3rd breaker to the
> system,
> or if these switches are actually rated @ 600 volts per contact.
> Also, I regularly used to switch both DC inputs until I was admonished
> by an
> electrician who insisted it was illegal to break the negative lead. I
> believe that he said this because of his assumption that the neutral in
> AC
> is grounded and it would be somehow interrupting the ground to break the
> neutral on the DC circuit as well. Why not switch both?
>
> Matt



Brad Bassett
Schott Applied Power
Tumwater, WA office
bsbassett at earthlink.net

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email to: RE-wrenches-unsubscribe at topica.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================