circuit breaker as an input device

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I have a sub-panel in my greenhouse that is fed by an incoming wire from th e main house panel. The incoming wire is directly feeding a 30 amp breaker , therefore I can disconnect the power to the panel by simply tripping the breaker therein. (Also within the panel are two additional 15 amp breakers , one for lights and the other for a single outlet.
I've always liked the convenience of the "breaker input" instead of hard wi ring the input directly to the panel. Does this method meet code? Any haz ards? Any down-side?
Thanks for all replies.
Ivan Vegvary
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On Saturday, August 24, 2013 9:47:29 AM UTC-4, Ivan Vegvary wrote:

er, therefore I can disconnect the power to the panel by simply tripping th e breaker therein. (Also within the panel are two additional 15 amp breake rs, one for lights and the other for a single outlet.

azards? Any down-side?

The code requires that all equipment be installed in accordance with it's l isting and marking. If you check that equipment in the listings you will f ind that you are instructed to use a tie down kit when using a plug on brea ker as a main breaker for the buss that it plugs on to. That is so that th e breaker can not be readily removed from the buss while it's buss clamps a re energized. Install the listed tie down kit and you are good to go.
Is the feeder to the greenhouse panel three wire or four? Is your greenhouse a detached structure in relation to the building in whic h the Service Equipment that supplies the feeder is located? If detached when was it built?
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Has anybody pointed out that breakers are designed to be ON most of the time, and once in a while kick OFF? and Switches are designed to be turned ON or OFF a lot? Simple thought process suggests that abusing a breaker to use it as a switch is going to have some long term, unexpected consequence. Like not turn ON when you want, or not kick OFF when you want.
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On Sat, 24 Aug 2013 07:45:15 -0700, RobertMacy

Just be sure the breaker is marked SWD. Then it is listed for Switching Duty. Most small breakers are these days.
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On 8/24/2013 11:13 AM, snipped-for-privacy@aol.com wrote:

lights in the church, built in 1984. They were not, iirc, rated for switching duty. After a few years, many started getting hot to the touch. They were replaced with SWD. And, in time, they started failing the same way. There were 13 such switches each controlling 2 light fixtures. I always wanted to put relays downstream to control the lights. There were about 3 or 4 different lighting patterns used depending on the building use, but it wouldn't be difficult to have groups of relays doing the job. Never did it as I moved. In another commercial building I specified SWD breakers to control TV studio lights and the powers to be, put in a breaker box and a separate switch box because, as they told me, breakers used as switches make for bad breakers. This was in about 2001.
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On 8/24/2013 11:58 AM, Art Todesco wrote:

The breaker panel is/has been the switching panel in the church here "since forever". It was replaced from the 1920's original in the early-mid 60s and hasn't yet had a failure since. Some circuits are all fluorescent, most aren't but nothing bad has happened in 50 yrs or so.
I've never tried to discover what the rating is; I'd suspect there being some other issue w/ the gear in your aforementioned location.
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On 8/24/2013 9:13 AM, snipped-for-privacy@aol.com wrote:

From the UL "White" book: "Circuit breakers marked 'SWD' and rated 347 V or less are suitable for switching fluorescent lighting loads on a regular basis at their rated voltage.
Circuit breakers marked 'HID' have been investigated for switching high-intensity discharge lighting loads on a regular basis at their rated voltage."
I don't believe using "SWD" breakers on ordinary loads that are switched is required, but it is a real good idea, particularly when they are readily available. The only breaker I looked at recently (SquareD 20A) was marked both SWD and HID.
SWD and HID ratings are probably for the increased arcing from an inductive load. It would be interesting if they are tested for more on-off operations than an 'ordinary' breaker.
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You will see lots of things done, but that does not make it correct.
There are some breakers that are also designed to be used as switches an can be cycled off and on many times with out a problem. http://ecmweb.com/qampa/code-qa-using-circuit-breakers-switch
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On 8/24/2013 10:23 AM, Ralph Mowery wrote:

NB that that applies only to fluorescent or high-intensity lighting circuits. I'd have to look up precisely the Code definition of "lighting circuit" to have 100% confidence but I'm pretty sure it doesn't include a general circuit that has one or two fluorescent fixtures included but is fluorescent-only or almost only load on same.
--



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t On 8/24/2013 10:45 AM, RobertMacy wrote:

switches.
--
Jeff

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On Sat, 24 Aug 2013 07:45:15 -0700, RobertMacy

The "main" he is using is not normally used as a switch but it gives him the ability to kill the panel if needed. The one breaker he is using as a light switch should be rated SWD. It is done every day in thousands of commercial and industrial buildings.
Your simple thought process needs to go a complex step further to understand this, I guess.
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wrote:

There are breakers that are rated for "switch" use. Residential breakers are not.
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On 8/24/2013 8:40 AM, Tom Horne wrote:

Also is required by the NEC - 408.36-D.
Good to see you at least once in a while.

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On 8/24/2013 9:47 AM, Ivan Vegvary wrote:

That does meet code and is the proper way of doing a small sub panel.
--
Jeff

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On Sat, 24 Aug 2013 06:47:29 -0700 (PDT), Ivan Vegvary

Yes

No
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On Sat, 24 Aug 2013 06:47:29 -0700 (PDT), Ivan Vegvary

Yes, no, no.
This is perfectly normal (I do it all the time). Electricity doesn't care about the direction it "flows" through the breaker.

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On Saturday, August 24, 2013 3:24:54 PM UTC-4, snipped-for-privacy@attt.bizz wrote:

ker, therefore I can disconnect the power to the panel by simply tripping t he breaker therein. (Also within the panel are two additional 15 amp break ers, one for lights and the other for a single outlet.

hazards? Any down-side?

To be completely precise it's not flowing either direction. It's vibrating back a forth a tiny bit.
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On Thu, 29 Aug 2013 13:59:02 -0700 (PDT), jamesgang

The energy is "flowing" one direction (there is a source and a sink) but the breaker can't tell which end is which.
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If I remember correctly, code "requires" a breaker in the main panel to feed the sub panel. Your 30 amp breaker protects the wiring that runs from the main panel out to the sub panel in your green house. If you were ever to cut the wire with a shovel or something, that breaker is what would prevent the whole system from shorting out.
The 15 amp breakers in your green house protect the wiring for your individual light and outlet circuits.
Your configuration is normal, and I have the exact same setup powering a sub panel in my shed.
However, unlike the main panel, the neutral bus should be isolated from the ground bus in the sub panel. You should also have an additional ground rod installed out at the greenhouse to suppliment the ground at the subpanel.

The US power grid uses "alternating current" (AC). The electrons flow from positive to negative, then reverse to flow backward from negative to positive (rising and falling in a sine wave). In the US the current alternates back and forth like this 60 times a second (60 hz). So technically, the electricity is flowing in both directions.
From a practical standpoint you have a supply (the power grid, generator, etc.), and a load (lights, heaters, radios, computers, etc.). Without the load, current isn't flowing either direction. :)
Anthony Watson watsondiy.com mountainsofware.com
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On Fri, 30 Aug 2013 14:48:36 +0000 (UTC), HerHusband

There are exceptions but that's certainly the way I'd do it. The issue wasn't feeding the sub through a breaker in the main, though. The issue was feeding the sub *backwards* through a breaker in the sub (with a breaker also in the main). This normal.

True but irrelevant. There is a "source" and a "sink". The breaker can't tell the difference, so it doesn't know it's being back-fed (which is the subject under discussion).

Huh?
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