Shore/Inverter Wiring for 120VAC DPDT 30A relay

ktmrfs wrote:
why not just put in a transfer switch. Most/all can easily handle this job and are designed and certified to do it. That's what I did. Mormally they are set up to transfer betwen shore power and generator, but the can be configured to switch between shore power and inverter just as easily. When configured for this, they can be set for no time delay for generator warm up.

I think that's what SMKettener linked to above. Wasn't aware of it at the time. If I had been would probably have gone that route as they're not that expensive. But they are a little big.

But finding an electrical box for this relay will not be that hard, and, hey, I'll save maybe $15-20 !!

MEXICOWANDERER wrote:
The NC contacts do not have equal ampacity as the NO contacts. Spring versus magnetic coil. The coil wins for strength.
...

Interesting & makes lots of sense, thanks. Just manipulating it by hand gives more pressure on the points when fully closed, as the coil would do. (And I see a contact arm or two needs to be adjusted as well).

Will definitely be running higher Amps under shore power, up to the full 30A with heaters and A/C. The inverter is only 1000W.

So another reason for Shore Power on the NO contacts.

Don't overthink it, find happiness with an ATS switch...

3 tons

The NC contacts do not have equal ampacity as the NO contacts. Spring versus magnetic coil. The coil wins for strength. I used a pair of 30-amp open frame relays on a 30-amp circuit. I check contact current ratings via their rated voltage. 480 or 240 rated 30 amp contacts can carry more than 30-amps. This helps with the NC ampere rating.

why not just put in a transfer switch. Most/all can easily handle this job and are designed and certified to do it. That's what I did. Mormally they are set up to transfer betwen shore power and generator, but the can be configured to switch between shore power and inverter just as easily. When configured for this, they can be set for no time delay for generator warm up.

Chris:
The advantage I see of hardwiring the 120V from the inverter (via the relay or that manual switch) is when you quickly pull over for a lunch break and want to use 120V for something or other.

I wasn't aware of the manual switch you reference but the relay was actually cheaper.

SMKettner:
Also wasn't aware of that relay in a box from BestConverter. Reasonable price. And I see you can disable the time delay. Got my relay on Amazon, but yes I gotta buy a box.

And you use yours with Solar & Batts and no problem with continuous relay activation on Shore power for long periods. I take it Best Converter didn't have any recommendations one way or another for theirs?

SMKettner & ScottG:
Should have mentioned that my inverter runs off the batts with solar recharge, no generator here.

So maybe I should trying putting the inverter on NC (like SMK) and save a few Ah when boondocking. Worst case is the relay will burn out somewhere in Florida while on shore power, and I can replace/reconfigure it there.

Anyway, won't start this project for another month, so have until then to decide.

Thanks for the comments.

Honestly, for the use you are describing, I would either do a plug, or a manual switch like this P&S 30 amp DPDT switch- of course, I wouldn't try to power the whole rig either...

I put my inverter to the NC and utility power to NO.
These are made for continuous duty either way.

Generator OTOH is usually connected to the NO contacts.

That relay should be in a box that would be included if buying a regular transfer switch.
http://www.bestconverter.com/Powermax-30-Amp-Transfer-Switch_p_436.html#.VWXgj02PK70

I would think the shore power would go through the NC contacts and only when the gen is started, the power would go through the NO contacts.