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Message |
Rdub (168.191.24.155)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2001 - 6:49 pm: | |
O.K. for the gazillionth time I need some help on this shore power deal. I cannot get a definitive from any "authority" I've spoken with. Tesla, Marconi, Watt...if you're out there please reply.
I have a 50A transfer switch. I ran 240v from my diesel generator to it. I was going to run a 30A shore power but realized the transfer switch wiring diagram called for 2 hots (240v)so I ran a 50A service. My inverter(next in line) a Trace RV3000, calls for 30A/split 2-120v input from the 30A breakers on the main breaker box (hot1 and hot2)to operate the charger and connect to it's own internal transfer switch and has a 30A output to go to the sub panel. I don't plan on plugging in to a 50A service very often since they aren't that common and I don't need it for power usage. If I use a 30A dogbone (adapter) how will that affect the transfer switch, inverter, et al? Let the games begin...Rdub |
Jim Stacy (32.101.44.175)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2001 - 9:34 pm: | |
Rdub,
The most flexible system is well within your grasp. You already have the 50 amp transfer switch and the gen set I assume is rated at 50 amps also.
Just for review the 50 amp service is rated at 50 amps for each of the two hot lines, 30 amp service is rated at 30 amps for one 120 volt line. You can see that 50 amp service is really more than three times the capacity of a 30 amp service. If you wire everything for 240VAC it won't make any difference if the two lines are in phase or out of phase. Many gen sets can be wired either way, most RV parks are wired for 240VAC.
With your unit wired for 50 amp service including a 50 amp shore line, you can plug in anywhere using an adapter for 30 or 20 amp if needed. The adapter will provide power to both sides of your breaker box so everything can run, just not all at one time since you are still limited to 30 amps total when plugged into 30 amp service.
Do NOT tie the white (ac common) to the green (ground) in your breaker box. DO connect them at the gen set side of the transfer switch. The inverter will usually tie them together when it is providing ac power. This way they are tied only at whatever is the source, be it the shore line (back at the first breaker box from the power co), the gen set, or the inverter.
If this doesn't make sense, please email me.
Jim Stacy |
Steve Fessenden (63.27.89.140)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2001 - 11:18 pm: | |
This is not advice on how to wire. Follow Jims advice for that.
Most RV parks may be wired for 240 volts but not at every site. I just spent a few days on 30 Amps in a 60 ft long space. I have found it is not uncommon to not be able to get 50 Amp 240 Volt service because someone else is already on the sites that have it. And there are some beautiful places that have only 30 amp services.
I would not use any 240 volt appliances or ACs if I could avoid it. You cannot run them from a 120 volt shore line.
It is possible on some generators to change the busbar connections in the generator so that it puts out its full load as a single 120 volt output. Check with the manufacturer of your generator to see if it is possible yours. I would mean you would have no worries about balancing the load.
You still split it into two legs at the braker box, as if it were 240 volt, so you can hook up to a 50 Amp 240 volt or to two 30 Amp services.
Steve Fessenden |
David Anderson (168.215.176.151)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2001 - 11:20 pm: | |
Here is what I did:
At my shore power box in my back bay of my bus. (It is a 50amp 2pole 240volt breaker box with only one breaker in it) I connected a 25' (code requirement is at least 25') shore power cord to the line side (supply lugs) of the breaker box. The load side of the 50amp breaker goes from the breaker to the shore power side of the transfer switch. The male pronged end of the shore power cord can plug into the campsite box. The neutral and ground are NOT bonded anywhere in this line.
If I want to use a 30amp or 20amp cord, I plug in my dogbone adapter to the end of the cord. This gives me 120volts on both legs of the 50amp 2pole breaker box, but remember it is only 30 or 20 amps. When you use the dogbone you cannot run anything 240volts.
When my genset comes on it automatically switches from the shore power contacts in the transfer switch to 240v 50 amp from the generator. This line is protected by a 50amp breaker of its own. My genset neutral and ground are bonded when the transfer switch energizes from the genset.
When I use the inverter, (no shore or genset power) I made me a 4 prong 50 amp female plug and bonded the ground and the neutral in this plug. I plug this into my male end of the shore cord. This bonds my inverter ground, inverter neutral, and battery bank ground all in the same location (no ground loops). After studying this for weeks, this was the cheapest and easiest way to achieve neutral to ground switching that I could engineer. I built this plug for about $12.00
You really should wire your shore power disconnect for 50 amp. It won't cost much more than 30 amp. There is never a penalty other than a few $$$ to make it bigger than needed and it makes all the transfer switching logic easier to understand. |
Steve Fessenden (63.27.89.140)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2001 - 11:31 pm: | |
I just noticed your Dogbone adapter question. You will have no problems. You can supply 120 volts to both sides of a 240 volt service providing you do not have any 240 volt appliances on it.
You cannot, of course go the other way. You would have a 240 volt short. Thats why you wire for 240 volt, so you can plug into the RV parks 240 volt 50 Amp service when available.
I believe your Inverter has to be wired to only one side of the service even though it calls for two 30 Amp breakers, they must be on the same leg to prevent supplying 240 volts to a 120 Volt inveter. |
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