ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Kichler Lighting Recalls Pendant Lights
by Admin - 09/18/19 08:47 PM
Does a 'normal 3ph-AC motor' include capacitors?
by gfretwell - 09/18/19 01:20 AM
Another weird NEC code question on Feeder Taps
by gfretwell - 09/18/19 01:14 AM
NEC 2017_392.22(B)(1)(b)
_What's the smallest width

by Bill Addiss - 09/17/19 07:13 PM
NEC Question_Cord-&-Plug EGC shorter then Neutral
by pcsailor - 09/16/19 05:26 AM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 6 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Gallery
Next Gallery
Print Thread
Rate Thread
Page 1 of 2 1 2
What's behind the door??? #215025 02/22/15 07:59 PM
IMG_1237.JPG
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline OP
Member
What's behind the door???

Found doing a walk-thru on a complaint
Have to check this out further next week.
Tools for Electricians:
13 Comments
Re: What's behind the door??? [Re: HotLine1] #215026 02/22/15 08:45 PM
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline OP
Member
OK, it's back to the sideways pics!!!


(Fixed - Admin)

Last edited by Admin; 01/24/17 09:00 PM.
Re: What's behind the door??? [Re: HotLine1] #215027 02/22/15 09:51 PM
Joined: Jul 2004
Posts: 9,392
G
gfretwell Offline
Member
I haven't got to OMG yet. How was the 250 stuff?


Greg Fretwell
Re: What's behind the door??? [Re: HotLine1] #215028 02/23/15 02:50 AM
Joined: Oct 2000
Posts: 2,720
Scott35 Offline
Broom Pusher and
Member
John,

Is this supplied by a 1 Phase 3 Wire System, or a 3 Phase 3 Wire Corner-Grounded System?

BTW, Notice that most of the Grounded Conductors for the Branch Circuits are Fused.
The only one that is not Fused is at the bottom of the Bus Kit.

Nevertheless, quite a find!!! thumbs clap

--Scott (EE)


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: What's behind the door??? [Re: HotLine1] #215029 02/23/15 10:48 AM
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline OP
Member
I have to look at this in more detail.
It looked like the neutrals are all fused, except the tap off of the top buss.

It's in an old school bldg. More to come.


John
Re: What's behind the door??? [Re: HotLine1] #215030 02/23/15 11:26 AM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline
Member
I seriously doubt that the 'neutral bus' is fused -- it's a corner grounded delta -- hence the fusing to the 'neutral' it's a grounded 'hot.'

I absolutely HATE to sling around the term 'neutral' in such schemes. While a corner grounded delta certainly has been pulled over to ground potential, it absolutely has circulating current pumping in and out of it -- at a tempo far beyond the residual imbalances typical of a center tapped residential service.

[ Unlike a center tapped Service drop, one dares not ever break the bonding to the ground while power is applied. What's bad for a center tapped ground is horrific for a lifted corner on a delta. ]

[ EUSERC hates this old time scheme so much that you'd need a Presidential Executive Order to have a new one hooked up. Emergency responders will always mistake the grounded corner -- from the layout of the panel -- to be that of a single phase, center-tapped scheme. Not good. ]

Off hand, it smells like a distribution panel for site lighting.

Which is exactly the kind of system that would run on and on for years without an upgrade/ overhaul.

I'd expect that the service was some ancient 240 delta.

That far back 480 was just not done for such facilities.


Last edited by Tesla; 02/23/15 11:33 AM.
Re: What's behind the door??? [Re: HotLine1] #215036 02/24/15 05:43 AM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline
Member
Since EUSERC hates corner grounded delta Services, I've never run across a single one.

I'd be interested to hear if a voltage tick reads 'hot' around such grounded legs of the power flow.

Let us know.


Tesla
Re: What's behind the door??? [Re: HotLine1] #215047 02/24/15 05:36 PM
Joined: Jul 2004
Posts: 9,392
G
gfretwell Offline
Member
I used to see corner delta on sewer lift pumps. As soon as I figured out what it was, I never saw anything unusual about it. It seems to have a certain elegance to it. A grounded conductor is a grounded conductor. It is simply an arbitrary decision at which point we ground the transformer secondary. I would be a lot more concerned with the center of a wye when you have reactive loads than a corner delta. It will only draw nominal circuit current. The main code/listing issue is that there is 240v to ground so the 2 pole breakers need to be "delta" rated.


Greg Fretwell
Re: What's behind the door??? [Re: HotLine1] #215052 02/24/15 10:38 PM
Joined: Jul 2004
Posts: 783
L
LarryC Offline
Member
Does it look to anyone else that many of the fuses have been replaced over the years? The labels on the fuses look too clean to be original. Why have they been replaced?

Re: What's behind the door??? [Re: HotLine1] #215068 02/25/15 01:31 PM
Joined: Jul 2004
Posts: 9,392
G
gfretwell Offline
Member
They look like they are FRNs so they may have been instant blow before and someone decided a delay fuse was a better option.


Greg Fretwell
Page 1 of 2 1 2

Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Trumpy
Trumpy
SI,New Zealand
Posts: 8,262
Joined: July 2002
Show All Member Profiles 
Top Posters(30 Days)
Admin 7
Popular Topics(Views)
258,636 Are you busy
194,231 Re: Forum
183,699 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3