Future rewire project and panel cleanup.

[MadMike78]

Going to rewire shop soon. Very old building and wiring is old and have some questions.

3phase main going to 100amp sub. Only 3 wires goung to sub. 2 hots and neutral. Theres a ground from sub to outside to ground.
This is attached to the one and only neutral/bus bar where grounds and neutrals terminate. Is this kosher?
I took out all the 3 phase THHN wiring as it used to be a machine shop and no longer has all equipment. Was tons of conduit running everywhere. Trying go for cleaner look. Going to do away with old "BX".

 

[MadMike78]

... More pics

 

[Mustang51js]

You going to stick with 3 phase or just install a new single phase panel.

 

[MadMike78]

Sticking with the 3phase.

 

[awdblazer]

so your replacing both panels or just the little one?

 

[Aceman]

You need 4 wires to the sub. I'd ditch the small cutler hammer sub for a bigger Siemens so it'll match the main panel. I'd also replace all the cutler hammer br breakers for siemens qp's in the main panel. It's NOT okay to mix and match brands of breakers. There are some exceptions, this isn't one of them. Also, while I'm thinking about it, breakers are pretty cheap, I'd replace them all. They are held onto the buss by spring tension, the last thing you want is to melt a breaker down on a buss stab because the spring got weak from old age.

Since you have a 240 3 phase high leg service any breakers that land on the 208v phase technically must be straight rated 240v and not slash rated 120/240. Inspectors over here are just now starting to enforce that.

Put welders and other equipment that doesn't use a neutral on the high leg if you can, that'll free up more spaces in your panel.

 

[MadMike78]

I hadnt planned on replacing either panel. Good point about breakers as ive noticed some play in some.
Why is there only 3 wires going to sub and a joint neutral/ground?

The neutral going to sub is about to fall apart. What gauge wire do I replace the sub feed with? Is Romex acceptable?

 

[alfredeneuman]

That system is a 120/240 High Leg Delta Connection.

2 of the phases measure 120 volts to neutral, and the third measures 208 volts to neutral. Any combination of phase-phase measures 240.

It isn't used much any longer, having been replaced with 120/208 a Wye connection that all 3 phases measure 120 to neutral.

There's no such thing as 220 Volt systems.

The higher phase on the Delta is marked with tape, by Code (the center phase)


That's why you have only 3 wires going to the subpanels, to provide single phase power for lighting and other 120 Volt power.

Machinery, A/C units and the such are run on the three phase service section.

 

[Aceman]

Why is there only 3 wires going to sub and a joint neutral/ground?

Because they did it wrong, you need four wires. You also need separate neutral and ground bars.

What gauge wire do I replace the sub feed with? Is Romex acceptable?

Whatever size you want that subpanel to be. I'm guessing that is a 100-125 amp panel, read the sticker on the door, you can feed it with any size feeder up to that size. Looks like a 50-60 amp sub right now with the wire size feeding it.

Romex/MC cable can't be ran where exposed to physical damage. Over here our inspectors would have us use conduit or flex to connect the panels together.

 

[MadMike78]

Yeah i know about the wild leg. It has orange tape on each tab down the panel. You can wire a welder to the 3phase wild leg? I wired it to the sub.
It is a 100amp sub!! What is the "correct" way to wire the sub and is it o.k. to use the current sub and do the correct way?
How does everything work if its wrong? Been that way since eho knows how long!
Not disagreeing, just trying learn.

 

[theoldwizard1]

That system is a 120/240 High Leg Delta Connection.

2 of the phases measure 120 volts to neutral, and the third measures 208 volts to neutral. Any combination of phase-phase measures 240.

It isn't used much any longer, having been replaced with 120/208 a Wye connection that all 3 phases measure 120 to neutral.

If it was my place, I would contact the power company and ask them what the cost would be to change to a Wye feed.

Then I would replace that mess with ONE new load center.

 

[MadMike78]

The more research I do they always have the griund and neutral separated in the sub panel and nit bonded to case. Atleast when its in same structure as main from what ive read. So was it common practice years ago to bring 3 wires over only and use the neutral and ground bus as one in the same?
I understand it being incorrect. To learn I ask why this is wrong
and whats the effects?
I just like to gain as much knowledge as I
possibly can absorb. Thanks. Mike

 

[alfredeneuman]

The consequence of having the neutral bonded to ground in any place other than the main service is objectionable current returning on the grounding system.

The neutral current uses any and all paths to return to the source, not just the path of least resistance as some folks believe. Some current would be flowing over the grounding system under normal circumstances when the neutral is bonded in this manner.

If you lost the neutral due to a bad connection, the entire neutral current would return via the grounding path if it could.

If the neutral is the sole mean of grounding, and it goes bad, the normally grounded items would have voltage with no place to go. That would provide one helluva shock potential were you to touch them and come into contact with a grounded surface

 

[MadMike78]

I plan on replacing subpanel. Siemens is what ill probably get per above advice. When I rewire it properly will I need the bare ground coming from outside the structure since it will have the 4 wires from the main? Im assuming no. I know to have neutral and ground separated and remove green screw from neutral. Neither is bonded to case either, correct? Im going to gather materials as I can so I appreciate all advice!

 

[alfredeneuman]

The ground bar should bonded to the case/enclosure. The neutral shouldn't.

They should be separate bars. You may need to buy the ground bar separately.

You don't need to bring the outside bare ground to the panel

 

[MadMike78]

Ive been looking at panels. I was looking at the $50 price range. What is the cause for difference in prices? I see some come w/breakers but besides that I dont see much.

 

[Aceman]

Ive been looking at panels. I was looking at the $50 price range. What is the cause for difference in prices? I see some come w/breakers but besides that I dont see much.

Get the biggest copper bussed Siemens panel you can afford. Main lug is all you need, but main breaker is fine too if you get a better price.

 

[alfredeneuman]

You'd be hard pressed, if not impossible, to buy a 3 phase panel in the $50 range.
Expect to spend at least $150-$200.

I don't think any of them come with breakers like in the Value-Pak single phase panels

 

[MadMike78]

You'd be hard pressed, if not impossible, to buy a 3 phase panel in the $50 range.
Expect to spend at least $150-$200.

I don't think any of them come with breakers like in the Value-Pak single phase panels

Im only replacing the subpanel.

 

[MadMike78]

I know exactly what needs be done now. I just have a couple more detailed questions regarding install.
The panel is on a block wall. The branch feeds will be running straight from sub up into attic of garage to disperse from there. I see in basements that the panels will be installed over OSB then the Romex stapled to the OSB. Is this fine to do?
I am going to use, more tgan likely, SE-R to feed subpanel. There wont be but 6-12"'s between the 2. I have some EMT I already have that can use. Do I need any special bushing or can I just use the connector with the set screw that holds the EMT and a lock ring that tightens to panels? Ive seen the byshings used on PVC so didnt know if there was same thing for EMT.

Thx. Mike

 

[alfredeneuman]

Im only replacing the subpanel.

Why replace it at all?

You've got plenty of breaker space left in the main panel if you need breaker space.

The Cutler-Hammer "CH" load center is the top of the line of plugin panels, is built of REAL metal as opposed to the more-plastic-than-metal panels of today, (Cutler-Hammer "BR" which is a real POS, all of the Siemens line, and all of the SquareD line).
Breakers for it are readily available, as the panel is still in production.

Just refeed it with a 4 wire feeder, and call it a day.

It's both Better AND Cheaper

 

[MadMike78]

You need 4 wires to the sub. I'd ditch the small cutler hammer sub for a bigger Siemens so it'll match the main panel. I'd also replace all the cutler hammer br breakers for siemens qp's in the main panel. It's NOT okay to mix and match brands of breakers. There are some exceptions, this isn't one of them. Also, while I'm thinking about it, breakers are pretty cheap, I'd replace them all. They are held onto the buss by spring tension, the last thing you want is to melt a breaker down on a buss stab because the spring got weak from old age.



Since you have a 240 3 phase high leg service any breakers that land on the 208v phase technically must be straight rated 240v and not slash rated 120/240. Inspectors over here are just now starting to enforce that.

Put welders and other equipment that doesn't use a neutral on the high leg if you can, that'll free up more spaces in your panel.

I was going on the above mentioned advise.

 

[AlwaysFixingSomething]

Why replace it at all?

You've got plenty of breaker space left in the main panel if you need breaker space.

The Cutler-Hammer "CH" load center is the top of the line of plugin panels, is built of REAL metal as opposed to the more-plastic-than-metal panels of today, (Cutler-Hammer "BR" which is a real POS, all of the Siemens line, and all of the SquareD line).
Breakers for it are readily available, as the panel is still in production.

Just refeed it with a 4 wire feeder, and call it a day.

It's both Better AND Cheaper

I don't know where you get your info from. I've been in the electrical trade for almost 20 years now and installed tons of different style panels like Siemens, CH, etc.. They aren't the best but they certainly aren't a POS. Siemens PL series comes with copper bussing and is a quality panel. Yes Cutler Hammer CH is the top of the line in my experience but the others aren't garbage.

 

[MadMike78]

So I guess its matter of choice if I install new sub. It would look better and fit in with theme of rewire. I would only spend about $50.
Any info about the conduit/bushing issue and the OSB to staple
off tge Romex going up into attic space.

 

[MadMike78]

Ill need to get an additional buss bar if I keep current sub. Will a midern CH bar fit? Panels too old to read anything off it.

 

[alfredeneuman]

Ill need to get an additional buss bar if I keep current sub. Will a midern CH bar fit?

Yes it will. The panels are still in production today.