Page 1 2
Go | New | Find | Notify | Tools | Reply | |
Mark1Mod0Squid |
Question 1: Is there any reason I cannot use a standard generator transfer switch to take two generator inputs and make them switchable manually into one output? Why you ask? I have a 14kw Kohler running on propane into my solar power system as a back up. My power system has an AGS and transfer switch built in, but can only accept input from one generator. Inside the load center for the solar there is a single lockout to ensure only one AC power source a time can deliver power to the inverters. Although I am not connected to the grid, I cannot use the slot for grid power for a 2nd generator as the power the system will be looking for on that slot would not be clean enough. Thus I would like to buy or fabricate a switch that I can use either the Kohler genset or a gas powered genset should I have issues with the Kohler. 1 is none 2 is 1. Question 2: This is really a shits and giggles question. What makes a 100 amp breaker panel rated as such? As in what is the physical characteristic of the panel that limits the number of circuits to 100 amps even if there are more slots open in the panel? _____________________________________________ Never use more than three words to say "I don't know" | ||
|
| Member |
No clue on Q1, but I want to follow this. For Q2- you fuse the wire, not the load. The busbars are rated for 100A. I'm not even a novice electrician, but my 200A panel, filled with 15A breakers, would total more than 200A 'allowable'. Obviously, your actual load would likely be well less than 15A on each circuit & 200A total. | |||
|
| You can't go home again  |
IIRC the max load on any circuit should be 80% of the rating. Snidera nailed it on Q2, to put it another way, breakers protect the wiring in the house NOT the thing plugged into the outlet on the other side. I'll try to find and upload a pic of what happens when you overload a panel, it's not pretty. The busbar was melted and the copper wires were so brittle, several snapped off when my hand brushed against them.  --------------------------------------- Life Member NRA “If you realize that all things change, there is nothing you will try to hold on to. If you are not afraid of dying, there is nothing you cannot achieve." - Lao Tzu | |||
|
| Member |
You could use a generator selector switch to choose whether generator #1 or Generator #2 would supply power out to your solar power system. Kraus and Naimer make selector switches we use in the marine industry to switch between 1 generator or a 2nd generator. | |||
|
| Member |
Jimmy is correct. Standard ship-to-shore switches do this. They are manual. They come in two pole on up to many poles. If you have three phase you would need four poles, as one is for the neutral. The grounds get bonded together. -c1steve | |||
|
| Mark1Mod0Squid |
If I understand you guys correctly, it is the busbar itself that limits ampacity? So what is the difference between a 100amp busbar and a 200 amp busbar? I am familiar with 80% load calculations on branch circuits but cannot find any difinative guidance on what makes a panel physically rated for a certain ampacity. Edit to add: I currently have a 125a panel that will eventually get moved into a cabin as a sub panel and replaced in my power center with a 200a panel. There is currently a 220/50a (RV), x2 120/15a, & x2 120/20a branch circuits in there. So I am at 120a of breakers using only 6 slots.
Are these ship to shore switches "lockout" style. So only one input at a time would be allowed to pass through? Only single phase 220 from either generator. Both will have Hot 1, Hot 2, Neutral, & Ground. One genset rated 220v/58a the other 220v/30a. _____________________________________________ Never use more than three words to say "I don't know" | |||
|
| Member |
Are these ship to shore switches "lockout" style. So only one input at a time would be allowed to pass through? Only single phase 220 from either generator. Both will have Hot 1, Hot 2, Neutral, & Ground. One genset rated 220v/58a the other 220v/30a.[/QUOTE] Yes, only output from 1 generator at a time would go through the selector switch. It's Either/OR never both. Both generators could be running and putting power to the switch, but only the generator selected by the switch would pass through. | |||
|
| Mark1Mod0Squid |
Excellent, sounds like a winner. Kraus and Naimer was mentioned, any others I should consider? Will google get me what I am looking for? Or do you by chance have a good source? _____________________________________________ Never use more than three words to say "I don't know" | |||
|
| Member |
and why doesn't a common 100a double pole safety switch (available everywhere not a marine item) do what you want? “So in war, the way is to avoid what is strong, and strike at what is weak.” | |||
|
| You can't go home again |
A 200 amp panel is physically larger in almost every way than a 100amp panel. The main busses are larger, the main breaker is larger, the wires coming into the panel are larger, and of course the panel itself is physically larger to accommodate more breakers. The heavier busses can handle the increased heat the extra current produces. --------------------------------------- Life Member NRA “If you realize that all things change, there is nothing you will try to hold on to. If you are not afraid of dying, there is nothing you cannot achieve." - Lao Tzu | |||
|
| Mark1Mod0Squid |
Well, because I didn't google "safety switch"? I was searching transfer switches and such. But now that I have and see they make double pole, double throw switches, it does exactly as I need and you have described. Thank you! Simple matter of nomenclature.
This is the answer that has eluded me. Thank you. _____________________________________________ Never use more than three words to say "I don't know" | |||
|
| Ammoholic |
re question 1: Yes, absolutely. That is what I did here. Installed a simple transfer switch with the propane powered Kohler as one input and a cable with a four prong, 50 amp 240 plug (NEMA 14-50) on the end as the other input. If there is an issue with the Kohler or if I just want more oomph for equalization, I bring up my Miller trailblazer welder, plug the cord into it, flip the transfer switch and fire it off. Easy peasy. | |||
|
| Member |
Busbars & other components of the box will be rated for max Amps. Same as you don't use 10Ga wire for a 15A breaker (although it will work perfectly fine), you don't use a 200A busbar in a 100A box - $$$$, component size, etc - but mostly $$$$. Again, you fuse the WIRE, not the load. Beyond that, it's a little bit of experience, voodoo & load calculation for how many breakers you can put in a box. You 125A panel is a good example, I'd look at the 15A & 20A branches & see what is on it - 15A with 3 light bulbs, you could count that as well less than 15A. 3 outlets with devices drawing 500W all the time, that one is overloaded to the 80% rule. | |||
|
Member |
Nice pic, LBAR15. That looks like a serious mess. This is why I like to convert panels from direct lug to main breaker when in doubt. I also like the tin plated copper bus panels, particularly the QO panel. Can’t a panel overload also be caused by a brownout situation, like when the utility grid is overloaded? Since P=V*A, a 100a panel at 80% has a 9600 watt load. If the voltage drops during a brown-out to 100v, then the panel is now at 100% load with the same 9600 watts, but loaded at 100 amps. You could see how a panel at 90% load would easily be overloaded with just a moderate drop in voltage from the grid. A main breaker would protect the panel against this scenario. I predict many more California panels looking like the one pictured, with PG&E’s ongoing problems. Demand not that events should happen as you wish; but wish them to happen as they do happen, and you will go on well. -Epictetus | |||
|
| Member |
Question 1. Yes. A couple options. Stand alone Double throw switch (on, off, on), GE, Square D.... Wire both generators into the switch, one output to your power panel. Wire a female plug/pig tail into your existing by-pass/gen input on your power panel. Wire appropriate size plugs/wire on each generator. Top option would be my choice and it'll be the more expensive. I've wired two generators for offgrid homes using double pole/double throw switch. Clean way to do it. Depending on the generators outputs, might have to change the generator input settings or draw on your power panel. | |||
|
Ammoholic |
Didn't read thread at work. All you need is a DPDT (double pole, double throw) switch that is service rated. Feed utility (solar in your case) in one side and generator into other side. As for limiting to 100a, it would be the main for total panel load, and individual CBs for individual loads. Jesse Sic Semper Tyrannis | |||
|
| Mark1Mod0Squid |
I am going with the Double Pole, Double throw option. It's so simple, but the nomenclature was getting the best of me. Thanks everyone else for the replies, I am smarter today than yesterday. Sigforum rocks. _____________________________________________ Never use more than three words to say "I don't know" | |||
|
Member |
I'm by far not an expert on this... but I would have just used a 60-80 amp plug and plug in and then just switched plugs.... but I presume double pole switches are better. My Native American Name: "Runs with Scissors" | |||
|
| Member |
It sounds like the OP's off grid and his main generator is already hard wired in with auto-start to supplement his Solar power on an as needed basis. | |||
|
| Ammoholic |
Yes. We have a similar situation. Normal mode the Kohler 8 RES propane powered generator is hardwired and auto starts. Flip the switch and plug the welder and you have 10kW of diesel powered juice on tap, but it’s manual. | |||
|
| Powered by Social Strata | Page 1 2 |
 | Please Wait. Your request is being processed... |
|
© SIGforum 2024