Electrical question from a dummy

[Janderso]

Hey all,
I moved my surface grinder yesterday, I need a power source for my 1 amp, Little Giant coolant pump.
The lead I marked with a red sharpie has 121V AC when the grinder is on = perfect.
This accessory port is not being used. I am hoping to just tie into this for my power source.
My question, where do I access neutral? Do I just use ground.
Three phase doesn’t use a neutral? Red, Black and white are 120, 120, 120.

Thanks
Jeff

 

[JimDawson]

No, 3 phase does not use a neutral. While using the ground as a neutral works electrically, it is not legal anywhere and a really bad practice.

If the transformer is large enough to supply an additional amp for the pump, then that would be a good place to pull the power from. Assuming it's a 120V output. I can't read the specs on the transformer.

Do you have 208V, 3 phase power? If that's the case, then there is a neutral in the system and you could bring that in to the grinder power panel.

 

[Janderso]

No, 3 phase does not use a neutral. While using the ground as a neutral works electrically, it is not legal anywhere and a really bad practice.

If the transformer is large enough to supply an additional amp for the pump, then that would be a good place to pull the power from. Assuming it's a 120V output. I can't read the specs on the transformer.

Do you have 208V, 3 phase power? If that's the case, then there is a neutral in the system and you could bring that in to the grinder power panel.

I wouldn’t know how to find the source on the transformer.
208v, I think it is based on the transformer label.??
Here’s a close up of the components.
The lead I marked red is T2 on the component I am pointing to with my Fluke.
Thank you for your help.

 

[woodchucker]

do not power up through the ground.
many on hear have already shed light on why it's not a good idea.
basically you are energizing your ground everywhere in the house/shop rather than it being a ground for protection... so == bad...
don't die.

 

[Janderso]

do not power up through the ground.
many on hear have already shed light on why it's not a good idea.
basically you are energizing your ground everywhere in the house/shop rather than it being a ground for protection... so == bad...
don't die.

I won’t do it!
That’s why the thread has the word dummy.
I should add this pic also.

 

[woodchucker]

yea, I am not knowledgeable on the subject. I did wire up my rotary converter, but you guys are way over my head. I know 120, 220v and very simplistic 3ph that I did.

But I pay attention to the warnings, so I don't kill myself.
My mom worked as a bookeeper for an electrical motor rewinding place, and she lost a guy to a very simple thing. He was taking the cover off an industrial panel and it blew, sent him into the wall across the room. He died instantly they said. from then on I realized the power of electricity, not just electrocution.. I don't have more details, I was young, but these days I figure the panel either hit a live buss bar, or there was something wrong in the panel.

 

[JimDawson]

Interestingly that transformer is 416/380/208 x 115/95, an odd combination I have not seen before. But only 0.25KVA (roughly 2.5 amps output max). Not quite enough to run that pump I think.

Since you are reading 120, 120, 120 on the 3 legs to ground, that would suggest that your building power is 208/120, and thus should have a neutral in the system. Check the voltage between the legs, I would expect to see around 208 between them.

 

[Janderso]

I checked the voltage on the device shown in this pic.
The grinder was running.
From left to right, 119, 119, 201.

 

[mksj]

It would be easier to get a 208-240 single phase pump and use two leads of the incoming power vs. bringing in a neutral. I assume you are running it off of an RPC? If so you would use the two pass through through legs going to the transformer, and voltages may be a bit different due to it being a high delta, I would not bring in a neutral to run a 120 VAC pump, and you would want the pump power fused in either case. Stock transformer is 250VA, the pump is 120VA, so power from X1 to X3 would be able to power a 1A pump but this assumes the transformer is not powering other devices. There may be an oiler system, or other devices powered by the transformer and it may not have enough total power for everything.

 

[Janderso]

Interestingly that transformer is 416/380/208 x 115/95, an odd combination I have not seen before. But only 0.25KVA (roughly 2.5 amps output max). Not quite enough to run that pump I think.

Since you are reading 120, 120, 120 on the 3 legs to ground, that would suggest that your building power is 208/120, and thus should have a neutral in the system. Check the voltage between the legs, I would expect to see around 208 between them.

When I said 120 across the board, I guess I was assuming since I know we have a 120v home.

I measured the supply voltage shown in the pic.

120, 120, 222 -that’s strange.
Everything works great! No heat, no noise. Been this way going on three years??