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buckeyebuck
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# Posted: 25 Apr 2016 10:30pm - Edited by: buckeyebuck
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We are wanting to use our solar to power 4 40 Watt light, charge cell phone, run a DC pump and maybe a radio. We have a 140 watt panel, one 12 volt battery (AMG), charge controller which is now running our 12Volt DC pump. Generator is now hook up to our service panel. Need to put in transfer switch, what kind do we need, also service panel is grounded. Do we need more grounds, discount switches and fuses?
Here is a rough sketch of what I think we need but not with fuses and discount switches.
Forgot to put inverter in sketch. I have been up to long 4:20 this morning to go turkey hunting
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bldginsp
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# Posted: 25 Apr 2016 11:45pm - Edited by: bldginsp
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A simple manual transfer switch will suffice, although I hope you don't have to spend a lot of money to get one. Most are made to handle a lot more amperage than you are using and so they are pricey.
Is your generator producing DC?
You always want to put a fuse on the positive wire coming out of the battery, and locate it as close to the battery as possible. Size the fuse to the conductor so the fuse would burn before the conductor in the event of a short.
So apparently your whole system is DC- if so, are your panel and breakers rated for DC?
I don't know what the grounding and bonding rules are for DC systems- I guess they are the same as for AC but I just don't know. I'm thinking of using a similar system myself, so I need to research it. Not sure where to start- household DC systems haven't been used since the late 1800s, far as I know.
But the basic idea with grounding and bonding with a transfer switch is that you don't want to disconnect the ground neutral bond by throwing the neutral in the switch. If the neutral is switched then the second power source must have its own ground neutral bond. If the neutral is not switched then the bond at the primary power source should be the only bond of ground and neutral.
But how this works with DC positive/negative I'm not sure.
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bldginsp
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# Posted: 26 Apr 2016 12:10am
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Good article on wiring marine DC systems:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/4829/SR%20no.%20622_ocr .pdf
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MtnDon
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# Posted: 26 Apr 2016 12:14am
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If you are keeping to a minimally sized system, and if there will not be any inspections, look (Google) for an RV automatic transfer switch. There are 30 and 50 amp, 120 VAC versions.
They have 2 inputs; the main one can be fed by campground grid power or an inverter. The secondary is for the generator. Most have a delay so when the generator feed is sensed in 30 seconds it switches from the main source to the generator.
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bldginsp
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# Posted: 26 Apr 2016 12:23am
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But Don you are presuming an AC setup. I doubt an automatic transfer switch can be used for DC, unless rated for it.
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buckeyebuck
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# Posted: 26 Apr 2016 06:49am
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Thank you bldginsp, we use 5500 generator for AC, we are wanting to run AC as our cabin is wire for AC except for the DC water pump
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MtnDon
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# Posted: 26 Apr 2016 10:01am
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Quoting: bldginsp But Don you are presuming an AC setup. I doubt an automatic transfer switch can be used for DC, unless rated for it.
He is running AC through the system... he stated he left the inverter out of the drawing... by accident.
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ack787
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# Posted: 26 Apr 2016 10:19am
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Could go with a 4 pole contactor 120v coil with 1 set normally open and one set normally closed. Normally closed side be your inverter (power/comon) normally open be your coil control with it tapping off for your power on the normally open side. When you fire the generator the coil pulls in which switches the power source from your inverter to your generator automatically. Then on the last terminals you add jumper wires to join the powers together and the comons together with the 2 wires going for panel feed.
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bldginsp
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# Posted: 26 Apr 2016 10:46am
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So he did- I take drawings too literally
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NorthRick
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# Posted: 26 Apr 2016 04:10pm
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I've got an automatic transfer switch similar to this in our cabin:
http://www.solar-electric.com/installation-parts-and-equipment/electrical-devices-tra nsfer-switches-noise-filters/autrswandgea/pomaxpmautrs.html
Connect up the AC output from your inverter and the output from your generator and then wire the ATS output into your panel. When the generator is off, the ATS feeds the power from your inverter to the panel. Start the generator, and after a short lag, the ATS disconnects the inverter power and connects up the generator power. When you shut down the generator, or it runs out of gas, a click and brief blink of the lights and you are back to the inverter.
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buckeyebuck
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# Posted: 27 Apr 2016 11:04am
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Thanks Don that is what I needed to know
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