[kfwittekiend]

My new Tormach 1100 came in last week and I am now trying to get it hooked up to power. I live off grid in Colorado and will be running the mill off the generator.
My generator is a Craftsman 6500 watt with a 4 prong 220 plug, however, when tested with a meter the hot on one side is 250V and the other hot is showing 120V. Is this normal or do I need to take the generator to an electrician to have a plug hard wired in for the mill?

Thank you for any help.

Ken

[VaderSpade]

It should be 120 on each side = 240. If you have 250 on one side something is wrong.

[VaderSpade]

The computer should be run from an inverter, or you have some other way of smoothing the power.

[Al_The_Man]

My generator is a Craftsman 6500 watt with a 4 prong 220 plug, however, when tested with a meter the hot on one side is 250V and the other hot is showing 120V. Is this normal or do I need to take the generator to an electrician to have a plug hard wired in for the mill?
Ken

You don't say what conductors you are measuring between or with respect to?
Is there 4 cond. on the plug or 3?
Al.

[wbleeker]

I am in Australia, our standard voltage is 240, but quite often the voltage at the outlet is 250, which my Tormach seems to handle quite alright.
I am sure that not all supplies are exactly what they are supposed to be due to distance from the supply or transformer, length of lead in cables or whatever- I am not an electrician :wave: but I do know that that small a variation dosen't matter, I run the Tormach controller on 240 volt setting as well.
I would ask Tormach their opinion about this first, you will get an honest and informed opinion from people who know their stuff, and if they don't know they will find out. The more I deal with Tormach the more impressed I get with them
in my opinion they are a truly awesome company to deal with. As an example I sent an email to Andy at just before 9am here this morning ( just before 5 pm there) and received an immediate reply, BTW it was only a setup query- nothing wrong.
Will

[tbaker2500]

It sounds like you are off a pin.
Put one probe on neutral. One hot should read 120. Then the other hot should read 120. Put a probe in Hot 1 and the other probe in Hot 2, and it should read 240 (or thereabouts).

If you are not sure of what you are doing, I highly recommend getting someone involved who is, it can be a very expensive mistake.

[Al_The_Man]

If the Gen. replicates the normal N.A. 120-0-120 plus ground as mentioned you should also ensure that the 0v or mid point is set up as a neutral by bonding it to a proper Earth ground electrode or water pipe equivalent, this would be done right at the 0v source point.
Al.

[Gerry Kmack]

Ken,
Where in rural CO are you? I am outside of Pagosa Springs. Will be ordering my 1100 later this summer.
Did you consider solar for your power? We have a son who lives off-grid in Guatemala, using only solar...powers his 220 tools just fine, though nothing as sensitive as a cnc machine.
Good luck with your new mill!

Gerry

[kfwittekiend]

Thank you for all the help.

The problem was that I was trying to use the actual ground prong on the plug. When testing with a meter and touching the ground and one of the hot receptacles the voltage readings were way off. The fix was to use the neutral as the ground and that gave 120V to each of the hot receptacles.

Thanks again for all of your help, the machine is making chips now.

[kfwittekiend]

Gerry Kmack,

I am over by Fort Garland, not too far from you. We go to Wolf Creek regularly.

The house is powered by solar, and soon to be wind, but I don't have enough money to setup a separate system for the mill. The batteries are crazy expensive.

Ken

[Al_The_Man]

The problem was that I was trying to use the actual ground prong on the plug. When testing with a meter and touching the ground and one of the hot receptacles the voltage readings were way off. The fix was to use the neutral as the ground and that gave 120V to each of the hot receptacles.

.

I sounds like the Neutral and ground are not set up properly?
Al.

[kfwittekiend]

It is some weird 120/240V Generator plug. I talked with an electrician and its supposed to be correct? Also fixed an earth ground to the generator.

Ken

[tbaker2500]

Congratulations you got it running!

Hmm, googled a bit and found this: Generator FAQ
It implies it's not bonded neutral for house tie-in:

"All generators should be labelled as either floating neutral or bonded neutral. The majority which I have seen are not labelled, and from my research are most likely neutral and ground bonded to the chassis. Using an ohmmeter to measure resistance between neutral and ground will confirm either way. Make sure the generator is not running while checking. Either way will work for home use, but the transfer panel must be wired differently in each case.

For a generator with bonded neutral, the transfer panel MUST be three pole and switch neutral for all circuits. The single connection point for neutral and ground will be in the generator. The ground wire will come back along the same cord and bond to the household ground.

For a generator with floating neutral, the transfer panel can be either two or three pole, but only TWO poles will be used. Neutral is not switched, and the connection point remains in the main service entrance panel. This is how my home has been wired. My transfer panel has three poles, but only two are used.

Using a generator with bonded neutral and ground in a system which does not switch neutral in the main panel leads to a potential safety issue. Neutral and ground will be connected at both ends of the extension cord, thus making them one conductor. As wire has a certain finite resistance, a voltage will develop when current flows through. This voltage will appear at the chassis and want to find a path to ground. Touch the chassis and you will be providing such a path. Normally this voltage is very low, but if there are problems elsewhere, it could become dangerously high. Safe operation can no longer be assured. Wired properly the neutral wire would be isolated at one end, preventing ground wire current and ensuring the chassis remained at zero volts."