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Joined: Mar 2011
Posts: 98
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Originally Posted by sparkync
it has been holding for 2 years at 19 amps.


If it's a standard 80% breaker that is amazing, but you have to wonder if all of the lights are on all the time too.

I am so familiar with 100% breakers because I spec them so often, most recently on a bunch of PV jobs. The switch gear for a large portion of these cookie-cutter jobs we've been doing has several 100% rated 500 amp breakers with parallel 250's to large inverters, the inverters have a maximum output of 440 amps at 480 so the breakers are fine. If we used 80% breakers we'd have to use parallel 350's and upsize the conduit and that would quickly cost more than the additional $500 or so for the 100% breaker since the distances between the inverters and switchgear are usually 200-400'.

We had a vendor supply us with an 80% breaker by accident this summer and when the array went online everything was fine until August when it tripped a dozen or so times. Every time the meter recording showed it tripping between 402 and 405 amps, right at the 80% rating.

So, having an 80% 20 amp breaker hold 19 amps for 2 years is exceptional IMO.

That circuit should really be split into 2 circuits IMO, but I don't think the circuit length and load is the issue on the 90 volt readings unless the total circuit length is around 500+ feet which it doesn't sound like it is.

Joined: Nov 2002
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Originally Posted by Vindiceptor
Originally Posted by sparkync
it has been holding for 2 years at 19 amps.


If it's a standard 80% breaker that is amazing, ...


Is it a counterfeit? Or made by FPE? smile

Joined: Mar 2011
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Originally Posted by wa2ise
Is it a counterfeit? Or made by FPE? smile


LOL

Joined: Jul 2004
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Quote
I sent a request in to the SQ.D company to see if they could tell me what the 20 amp QO breaker was actually rated at.


Me too I bet they are wondering what is going on.

I did look at the online documents I could find on QO breakers and they keep talking about the NEC 80% rule.
The trip curve does make it look like they will hold at the rated capacity forever at or below 40c.


Greg Fretwell
Joined: Jul 2004
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Subj: RE: Product Technical Inquiry [T20111104011NS010Z4733638]
Date: 11/4/2011 3:57:57 PM Eastern Daylight Time
From: ContactUs_Web@us.schneider-electric.com
To: gfretwell@aol.com
Sent from the Internet (Details)



The QO is standard rated (80%) for continuous loads of 3 hours or more. 100% rated for loads less than 3 hours.

___________________________________________________________________________

Marshall Barker | Schneider Electric | North America | Senior Product Support Specialist - Circuit Protection

Toll Free: +1-888-778-2733 | Fax: +1-319-369-6600

Email: cedarrapids.psg@schneider-electric.com | Site: www.schneider-electric.com

Address: 3700 6th Street SW, Cedar Rapids, IA 52404


On November 4, 2011 at 12:01 PM, gfretwell@aol.com wrote:

>
>
>


Greg Fretwell
Joined: Oct 2002
Posts: 830
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Greg, you must have special connections with Sq.D
I haven't got my response yet. I have got a response back from "South Wire". They only point me back to the NEC. I was hoping they could tell me actual data from their laboratories:)
BTW, Wa2ise, it is Sq.D not FPE thank goodness:)

Last edited by sparkync; 11/04/11 07:49 PM.
Joined: Nov 2007
Posts: 763
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As far as I can tell from looking at their catalog, the regular SQD QOB style breakers are only available with the standard 80% rating. The SQD PowerPact molded case cbs are available in either the 80% or 100% rating, but these apparently wont fit the standard QO or NQO panelboards.

Joined: Jul 2004
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THHN is usually multirated MTW with a 105c rating so I bet that stuff could get so hot you could cook a chicken on it without any serious insulation damage but that does not relieve us from 240.4(D) or in special cases 310.16.


Greg Fretwell
Joined: Apr 2002
Posts: 7,335
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Greg:

Back on page 3, I threw in the heat deterioration comment, with the word "eventually".

Occasionally, from field experience as an electrician & contractor, I stray from the hair splitting ways of reading the NEC, as do the majority of people I deal with as AHJ.

Trade practices, exceeding code minimum and maximum standards are hard to forget sometimes.

All that said, and not to 'fan any fires'.....how long did ya cook the chicken??? LOL


John
Joined: Jun 2004
Posts: 1,273
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These days THHN is usually rated THWN-2 AND MTW...

THWN-2 is very important since it permits reasonable wire size for underslab conductors.

Trick anything might be possible.

In the commercial trades 80% is a hard limit.

Everything about this circuit smells like the EE thought that 277 VAC would cut it.

Yet the EM ballast world is not oriented towards 277 VAC; namely the battery inverter scheme.

I've seen this addressed time and again only at the last minute as a change order -- in the field.


Tesla
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