Oversized Ground for Well Pump?

[ritelec]

Good morning all.

Customer has a well pump controller to be relocated.

It's not the the usual that I've seen.

It's large, 34" length, 16" wide, 16" deep.

Inside it looks like a large board with components maybe rectifiers and things.

It's fed with 8/2 rx on a 45a..........and the load goes out with 4-#4's. A green (on load terminal), two colors (on terminals), and a yellow which lands on a terminal labeled white.

Talking to the owner he says this thing costs like 4 grand so I'm hoping he has a phone number to be able to get some info on it.

But my question is.

I'm going to splice the line's and loads to extend them.

I picked up 4/3 MC to extend the load.... But I can't figure out why the original load green would be a full sized #4.

Is it DC? Is there something I'm not getting? Like the yellow going to the white terminal (which I'm assuming
was at hand to use) , did someone just have and install the #4 green instead of the
10,8,or 6 equipment ground?

Any thoughts?

I'll let you know if I find out anything.

Thanks
Rich

 

[ptonsparky]

Sounds like a VFD. Almost all literature is available online now. "Suggested reading" is what I would call it. Maybe required reading.

Other then that, and the EG increase we talk about so much here, I think it is what they had in the truck. My thought is the line side is undersized if that is a VFD taking 1ph in and putting 3 out.

 

[iwire]

Perhaps they are using the well casing as part of the grounding electrode system?

Just a shot in the dark.

 

[kwired]

The output may be larger because of long length and voltage drop. If that is the case the equipment grounding conductor must also be increased proportionally in size.

I do agree this sounds like it is probably involving a VFD.

 

[ritelec]

Thank you gents

It's not part of the grounding system as I see.
VD? Maybe. Two hundred feet down from what owner says.
Undersized feed for 3 hp? Good catch. I saw 3 hp on plate
Yesterday and thought the same.
Been working for years so ? ??
Green # 4 on truck?

Just pulled up

 

[Little Bill]

Thank you gents

It's not part of the grounding system as I see.
VD? Maybe. Two hundred feet down from what owner says.
Undersized feed for 3 hp? Good catch. I saw 3 hp on plate
Yesterday and thought the same.
Been working for years so ? ??
Green # 4 on truck?

Just pulled up

Geez, you have no patience if you've already "pulled up" the conductors or pump!

 

[ptonsparky]

I would want to get rid of green #4 if it was on my truck. Tape is a lot cheaper to stock.

 

[ptonsparky]

For a 3hp increasing the phase conductors would require the aformentioned increase in EG. Odd that someone actually did that years ago.

 

[kwired]

For a 3hp increasing the phase conductors would require the aformentioned increase in EG. Odd that someone actually did that years ago.

good chance those conductors are maybe submersible pump cable, so it may be possible a 4 AWG cable included a 4 AWG green conductor. Can't say I have ever seen submersible pump cable that large, but I'm sure they exist.

4 AWG seems like overkill for only 200 feet on a 3 HP motor though, especially if it is a 3 phase motor. I come up with about 8/10'ths of a percent voltage drop for a 240 volt single phase 3 hp motor at full load with 200 feet of 4 AWG supplying it, and about 4/10'ths of a percent voltage drop if it were a three phase 240 volt motor.

 

[ritelec]

Moved the vfd yesterday.

Just an update and thanks for the feedback.


The 4's turned out to be #6 thw or tw or....

The ground was a 6 or 8 ... not sure.
It got the 8 from the MC.

:- )