Generator wiring question

Oh, no. Don't ask someone else. If you're going to wire it yourself, discover it yourself. It'll be in the manual, too.

I got some of these from Ebay for my solar setup. Manual Transfer Switches, aka ORred circuit breakers. They run from 3A to 63A.

You have to physically turn one off before the other will engage.

No, it's much more likely to have phase lines (120vac) plus a ground for the genset. US 240vac has no neutral, only the 120vac does (line, neutral, and ground).

CAREFULLY. If in doubt, hire an electrician. Do the box install, switch install, and wire running yourself, and just have Sparky connect the wires to save money. Call them first to see if they will allow you to do that, though. Some want to do it all themselves. I saved $100 by doing my own wiring/outdoor breaker box for the A/C unit.

Look at the genset diagram, look at the wiring from the socket, and follow the colors they use on your socket and extension cord. (black white green, black white bare, black red green, or black red bare usually. Green/bare is always ground.)

I'd run the two phase wires from the output of the circuit breaker to the rotary or MT switch Input 1 terminals, run the two phase wires from the genset to the rotary MT switch Input 2 terminals.

Then I'd run the existing wires (removed from the existing circuit breaker outputs) to the output terminals from the rotary or MT switch. Those wires go directly to the dryer socket on the wall. And run the ground from the genset to the circuit breaker panel ground bar. Be sure to cover the hot side of the switch, so fingers couldn't accidentally touch the hots. That hurts.

Is your generator box outside, near the circuit breaker box, so you can drill a hole, put in a waterproof socket, and make a short extension cord from the genset to the house, where the switch will go? It makes things easier.

I bought a 250' roll of 12/2 w/ ground Romex for outleted circuits and

100' of nice, flexible 12/3 wire for 240v bandsaw/DC/tablesaw and extension cord when I got this new-used house. There was no 240v in the (2-car) shop, so I put in 3 outlets, ran the wiring, and removed the 240v electric wallboard heaters, reusing the old circuit breakers for the shop.

Greetings Terry, Maybe you can educate me a little. After reading posts in reply to my post I got out the amp clamp and measured the current on both wires of the 125 volt receptacles in my shop. Plugging in a motor and turning it on the meter shows the same current draw on both the neutral and hot wires.In this case approximately 2.8 amps. I wired my shop with wire ways so it is easy to make measurements as the wire way covers come off easily and the wires just lay in the wire way. All the 125 volt receptacles on one wall are fed from the same breaker, on another wall another breaker, and so on. I did balance the load in the breaker panel so that two walls are fed from one leg of the 250 volt supply and two walls from the the other leg. I don't understand how the neutral can be balanced and show less current than the hot except at the breaker panel where the power comes in. What am I missing? What don't I understand? I did wire the shop myself but I was helped by a licensed electrician, the electrical code book, and the wiring was inspected and bought off by a particularly picky inspector. Thanks, Eric

each on one leg of the 220 power supply and to neutral . Putting your meter on the neutral should show zero or very close to it . Look at it like you've put 2 110 volt loads in series across a 220 supply with the connection between motors hooked to neutral . If the two loads are unequal the difference is carried by the neutral . If the two loads are the same neutral current will be zero .

The neutral of a 120/240 circuit is a SHARED neutral. From the point where the 2 branch circuits join, a balanced circuit neutral carries no current. Yes - every branch circuit neutral carries current, but if the load L1 to neutral and L2 to neutral are exactly equal in both current and power factor, there is no current flow in the shared neutral.

Take a transformer with a center tapped secondary and put the same load on each side of the secondary.

Lets say it is a center tapped 24 volt secondary - with 12 volts on each side of center. Put 12 ohms across each side. You get 1 amp flowing through each load to the center tap. You get one amp total current in the secondary - so what current is flowing in the center tap? ZERO.

There can be NO OTHER ANSWER.

The neutral current will be zero only on the grid side of the breaker box neutral terminal block. The current going out to each grinder through the black wire will return through the white wire, then pass to the other grinder's white wire through the terminal block.

implies .

I'm not touching that one.

I get that Terry. But since only one grinder is plugged in the neutral has current on it. So in my shop the load is almost never balanced. This is because even though the receptacles may be the same number on each leg the stuff plugged into them and running is almost never the same load. I'm glad I got that cleared up in my mind. Eric

I got a little confused because the 125 volt loads in my shop are almost never balanced. BTW, the reason I wrote 125 and 250 volts is because that's what the voltage measures to my shop. Sometimes surges higher too. PSE says it's all good. All my CNC machine controls have multi tapped transformers so the high voltage is OK for the controls but one machine has a VFD that can't handle the voltage spikes and shuts down. When decelerating the spindle the energy is fed back into the incoming power and this also causes voltage spikes. I had to wire in two buck transformers to lower the 3 phase voltage for the one machine to fix the problem. Eric

I'd say that "right" implies that otherwise is wrong and it really doesn't make ANY difference, except to the power company. Because the only neutral current that you're minimizing is that in the "drop" to your panel. You have no control over the neutral currents in your panel and circuits.

your statement that I have "no control" over neutral currents . I may not have a perfect balance , but I have a pretty good idea of what loads will be on most circuits and that influences my decision on which leg to place that load . And what difference does this make ultimately ? Probably not a helluva lot . But if I can somewhat balance the load that my supply transformer sees that can only be good . Or should I draw the whole 200 amps (or as much as is 110V loads) my panel can handle from one side ? If for no other reason than voltage sag I can't call that a good idea . Symmetry !

Careful, now... I said "in your panel and circuits". Your balancing does not affect any neutral current in your branch circuits. Only in the aggregated current in the neutral wire coming to your panel.

Unless you are using "edison circuits" - or sub-panels

If it was we wouldn't need a neutral wire, but the fact remains the neutral will NEVER carry ALL of the load current if any of the load is devided between lines. If that were not true the neutral would need to be double the capacity of the "line" conductors.

It's all about control. ;)

I'm lean toward Eric and Jim's side of the fence, but I understand where you're coming from. Old style electricians used to try to balance circuits, with lights on one 120v leg and outlets on the other

120v leg of a 240v panel. That's a good thing.

May the EMF be with you.

What? You guys don't grind ambidextrously for load balance?

I think the NEC demands those only in hospitals. Everyone else has 2 hots and a not. (safety ground w/ no current)

Required for ranges and driers for at least the last 10 years here in Canada - don't know abiout the backwaters of the USA>

"Whatever for?" he queried, from said backwater.