Two Wire Sub Panels

Al Pike

Member
Location
Honesdale, Pa
A common installation I've been running across is two wire sub panels for 220v HVAC units. The electricians are installing 4/8 circuit 125a ML panels typically with 4/2 w/6 ground bonded with the screw to the provided bar. Then they'll install 2-30a 2pole breakers for each unit.
My problem is it leaves a potential future problem with someone tapping off for a 110v circuit, I've ran across it already. I've required labeling to be installed stating 220v power only no grounded conductor at the panels. Am I missing something or is this a normal application instead of installing 3-wire. We're only 20ft from the panel and I don't see why two cheap 60a 2pole disconnects aren't used with two separate circuits. Thanks for the input.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
A year or two ago, I ran SE cable from an outside disco to a second 200a panel to supply a tankless water heater. The inspector failed me despite my explanation that the bare is the neutral to the new disconnect, and the EGC from there to the panel.

He insisted that a neutral is required in any feeder, and called his boss (whom I know) at my request, who initially agreed on the phone, but then he called back a few minutes and agreed that I was correct: no neutral loads, no neutral required, so pass it.

This is not so different from the six-breaker/no-main-breaker-needed rule, or allowance, even if you use a panel with additional empty spaces. It's up to a future installer to comply with the requirements being enforced at the time of any future work.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector
sure, you can suggest all you want, but don't expect compliance form me.
Luckily in my area, likely due to75% of my, inspections involve some "teaching"as opposed to rejections, "suggestions" are normally graciously accepted.:)
 

norcal

Senior Member
While it would be nice to have signage that the panel is 240V only, no neutral present, any qualified electrician should have no problem figuring out that a neutral is not present, there will be those who will use the grounding conductor as a bootleg neutral, but one cannot go by "what ifs".
 

kwired

Electron manager
Location
NE Nebraska
If you put a sign there the non qualified will not understand what it is saying or ignore it altogether and connect a 120 volt load anyway.

Those that are truly qualified will know there is no usable neutral there right away.

I have done this occasionally with 120/240. Done it a lot more if only one 240 volt load is being supplied. Done it a lot with 480 volts when there is no 277 volt loads to be supplied.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
A year or two ago, I ran SE cable from an outside disco to a second 200a panel to supply a tankless water heater. The inspector failed me despite my explanation that the bare is the neutral to the new disconnect, and the EGC from there to the panel.
By the way, I did remove the neutral bus.
 

kwired

Electron manager
Location
NE Nebraska
By the way, I did remove the neutral bus.
If you installed a EGC bar those non qualified will land the neutral on that and not even give it any thought as to possibly being wrong.

Even if you just drilled and tapped a ground screw they pretty likely to still land a neutral on it if determined to supply a 120 volt load from there.
 

Frank DuVal

Senior Member
Location
Fredericksburg, VA 21 Hours from Winged Horses wi
Occupation
Electrical Contractor, Electrical Engineer
Not running a neutral is perfectly legal.

But, having to add a neutral to too many runs where "three phase" was called for and wired with 4 wires (three hots + ground) and then when the equipment is purchased years later, it needs 120 also...... I will always run a neutral and charge for it. Knowing I may well be the person who needs it later!

"But they will never want to pay extra for it", well, if not given choice how would they know ...
 

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
I ran into this last year. A mansion was being used to host a fancy-pants party, and the caterer needed 3ph. power (with neutral) for all the cooking equipment being set up outdoors in a food tent. I was told that there was a 3ph. 200A panel that served the AC compressor "farm" near where they wanted to set up.

I opened the panel to do a Cam tail tie-in, and lo and behold, no neutral. All the AC loads were L-L-L. That hadn't stopped someone from bootlegging off the ground bar for a service receptacle and post light though... ugh. I told the event manager I couldn't do the tie-in there safely. We found a panel in the basement to tie into, and the catering company ran LOTS of Cam feeder most of the way around the house into the back yard. I didn't see the bill for the last minute delivery of 250' of rented Cam feeder, but I'm sure it wasn't cheap. The people throwing the party could afford it :)

Neutral may not be required, but is often appreciated down the road.



SceneryDriver
 

cpickett

Senior Member
Location
Western Maryland
Occupation
Electrical Engineer
He insisted that a neutral is required in any feeder, and called his boss (whom I know) at my request, who initially agreed on the phone, but then he called back a few minutes and agreed that I was correct: no neutral loads, no neutral required, so pass it.
This industry certainly is broad, go into an industrial plant and the majority of 480V feeders won't have neutrals at all. Perfectly legal if there are no line-neutral loads.
 

kwired

Electron manager
Location
NE Nebraska
I ran into this last year. A mansion was being used to host a fancy-pants party, and the caterer needed 3ph. power (with neutral) for all the cooking equipment being set up outdoors in a food tent. I was told that there was a 3ph. 200A panel that served the AC compressor "farm" near where they wanted to set up.

I opened the panel to do a Cam tail tie-in, and lo and behold, no neutral. All the AC loads were L-L-L. That hadn't stopped someone from bootlegging off the ground bar for a service receptacle and post light though... ugh. I told the event manager I couldn't do the tie-in there safely. We found a panel in the basement to tie into, and the catering company ran LOTS of Cam feeder most of the way around the house into the back yard. I didn't see the bill for the last minute delivery of 250' of rented Cam feeder, but I'm sure it wasn't cheap. The people throwing the party could afford it :)

Neutral may not be required, but is often appreciated down the road.



SceneryDriver
Was there enough capacity after AC loads were factored in? With a party going on it likely will be running.

If there was enough capacity, could have possibly derived a neutral with separately derived system? Might only needed smaller system for line to neutral loads and let line to line loads connect to the existing.
 

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
Was there enough capacity after AC loads were factored in? With a party going on it likely will be running.

If there was enough capacity, could have possibly derived a neutral with separately derived system? Might only needed smaller system for line to neutral loads and let line to line loads connect to the existing.
It was a Halloween party, so little to no AC needed. Definitely enough power available; just wouldn't work without the noodle. The panel I ended up tying into in the basement fed the AC panel anyway. It was just A LOT more feeder than the event manager was anticipating. For once, I didn't care; I was just the sparky doing the tie-in. Once the Cam tails were in, I was able to leave (Not my circus, not my monkeys).


SceneryDriver
 
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