1940's SQ D 3ph/1Ph a/c combo Panel ?? sub panel fed A-C-A???

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rt66electric

Senior Member
Location
Oklahoma
I was doing a estimate for old house sale or home inspection punch list.

this located in aone of the few parts of town with residential 3ph power.

100amp 3p service without a main breaker.
orginally built in 1940s ? with added and a addonon added on and a 1970's mother-in-law addition. grandpa did somework here and there. overall well maintained and in good shape appox 2800 sq ft

I opened upthe sq d panel to find why it was 3ph but had 4 single breaker in a line???

Iexpected to find a wild leg setup-
I had to triplecheck and go get my other meter I found that the top 3ph breakers had wild leg -----but ----------the lower breakers were only 2-pole?????

has any body ran into a similar panel???

I seen similar housed built in that time frame for early 3ph A/C systems, but never a special panel as such.

I did not ahve time to pull breakers to check the bus bars, but the lower visable buses below the breaker only had phace A-C visable and a space for "B" ????

NOw for the BIG DELIMIA

The mother-in-law addition appears to be fed by a 3PH 60 BREAKER ----but--
upon inpection of the sub-panel it appears to be 3phase panel w/main HOWEVER-- it is fed 60amp phase A-C-A instead of A-B-C !!!!

I can tell that this is where the sub-panel installer may figured out his mistake(OR NOT) and installed all the 2pole breakers in a skipped order to acheve 240 instead of 120/120 same phase


WHAT DO YOU TELL THE CUSTOMER??????

I talked quietly to the home inspection who happened to be there on afollow-up. The report was very through accurated and well done, and caught the standard/typical problems. but knowing the difference between a 3ph wild leg system or a single 30amp one leg systemwas above is training level.


other than that, I know the realtor/buyer/seller does not want me to cry chicken little and blow the sale. what should i do ,, I would have to get the chalkboard out to explain it the the buliding inspector. I really donot want get him involved unless asked to
Most items on the puch list are easy to fix, open splice/mssing gfi etc
I could fixthe items on the list, make few $$ and run---OR--- or cry wolf and loseout???
times are tuff and work is slower. DENNIS
 
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Volta

Senior Member
Location
Columbus, Ohio
rt66electric said:
I was doing a estimate for old house sale or home inspection punch list.
...
has any body ran into a similar panel???
Click to expand...
Sort of. I have recently worked on a 3ph SQD QOB panel, 54 spaces*, bottom 18 spaces are ABC, top 34 spaces are AC, middle two are unusable / no bus. No main breaker, 225 amp bus.
....WHAT DO YOU TELL THE CUSTOMER??????
...other than that, I know the realtor/buyer/seller does not want me to cry chicken little and blow the sale. what should i do ,, I would have to get the chalkboard out to explain it the the buliding inspector. I really donot want get him involved unless asked to
Click to expand...

Who is your customer?

Is A phase overloaded? Are multi-wire branch circuits sharing a grounded conductor from two A-phase breakers?
 
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rt66electric

Senior Member
Location
Oklahoma
chris kennedy said:
Shunt trip?
Click to expand...

I have often seen people install a single-pole breaker on the wild leg and let the smoke out of whatever was plugged in the rec. (which is what i was expecting) the 4 breakers in a line are refering to say .. for example #'s 10,12,14,16 or such.

I called a few other knowlegable EC's . One could barely remember a similar set-up but never in a residential manor.

The other EC has seen some three ph residential primiative A/C, But not his type of peculiar panel
 
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rt66electric

Senior Member
Location
Oklahoma
Volta said:
Sort of. I have recently worked on a 3ph SQD QOB panel, 54 spaces*, bottom 18 spaces are ABC, top 34 spaces are AC, middle two are unusable / no bus. No main breaker, 225 amp bus.


Who is your customer?

Is A phase overloaded? Are multi-wire branch circuits sharing a grounded conductor from two A-phase breakers?
Click to expand...

my customer is the buyer

Oh yea DUH, I knew there was a easy answer, I was so flaberghasted, and rushed by the selling realtor, that I havent had time to assimlate my thoughts.
 
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Volta

Senior Member
Location
Columbus, Ohio
rt66electric said:
my customer is the buyer

Oh yea DUH, I knew there was a easy answer, I was so flaberghasted, and rushed by the selling realtor, that I havent had time to assimlate my thoughts.
Click to expand...

Gotcha. Well that does make it easier for you to work it out with your customer. It is great when the buyer is the one to satify, so you won't be asked to 'just make it seem ok' at least.

I would think that you need to determine if it is safe as-is. If not, then work is needed, and the value between you and the buyer can, but need not be precisely the amount of money represented in the seller-buyer's contract.

If it is not overloaded now, then you will want to ascertain how close it is to being so, and how likely it will become that way with future plans, and discuss it with your customer.
 
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rt66electric

Senior Member
Location
Oklahoma
Volta said:
Gotcha. Well that does make it easier for you to work it out with your customer. It is great when the buyer is the one to satify, so you won't be asked to 'just make it seem ok' at least.

I would think that you need to determine if it is safe as-is. If not, then work is needed, and the value between you and the buyer can, but need not be precisely the amount of money represented in the seller-buyer's contract.

If it is not overloaded now, then you will want to ascertain how close it is to being so, and how likely it will become that way with future plans, and discuss it with your customer.
Click to expand...

Thank you for your time
Whatis the best way to determine the size needed for a dwelling?? do you have arule thumb .. add up major loads---a/c hot water,lights etc
Its been sssoooo long ago since Ive practiced that in "PUP school" I would go nuts trying to refigure the official nec long form version
the original size house wasApprox 1200sq ft. the finishedversion is closer to 2800sqft. I have not had the opportunity/time to determine the majorloads. The older partof the house andheating is gas the newer part is proably all electric.
 
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Volta

Senior Member
Location
Columbus, Ohio
You can use optional methods in Article 220, Part IV, or 220.83.

But without knowing other HVAC loads, I'd start the regular way.

Two dwelling units.

2800 sqft * 3va = 8400
4 SABC min * 1500va = 6000
2 Laundry * 1500va = 3000
Small appliance and lighting: 8400+6000+3000=17400va
First 3000 @ 100% = 3000va
Next 14400 @ 35% = 5040va
Small appliance and lighting derated: 3000+5040 = 8040va

You are at 34 amps, 240 volts, single phase.

Ranges?
Dryers?
Water Heaters?
HVAC?
Disposals?
Dishwashers?
Microwaves?
Sump pump?
Well?
Hot tub?
Kiln?
Freezer?
Workshop?

Are there any 3 phase loads? We know that the 2-pole loads in the sub panel are on A-C, the only loads on A-B or B-C will be in the main panel. Moving 2-pole loads off A-C to another phase set in the main will help.
 
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rt66electric

Senior Member
Location
Oklahoma
Thanks for your interest

Thanks for your interest

thanks for your interest. I managed to convince the selling realtor that I missed something in order to get a better look tommorow. Then I will be able to actually pull the breakers to see the buss bas and make notes to calculate load Dennis
 
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rt66electric

Senior Member
Location
Oklahoma
I have never seen a delta breaker

I have never seen a delta breaker

norcal said:
Are you sure the breaker is not a delta breaker? They would have 4 breaker poles.
Click to expand...

I have never seen a small >200amp delta breaker 4 breaker? actually used in a service anywhere?? although I have seen a panel in the junkpile
 
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jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
norcal said:
Are you sure the breaker is not a delta breaker? They would have 4 breaker poles.
Click to expand...
A Square D QO delta breaker was only three poles wide. 2 poles plugged on like a standard breaker, the third pole had two wire connections on the load side (similar to a GFI breaker) and no plug-on connector.

The only 4-wide QO breaker was a 3-pole unit with a 'module' added (either a shunt trip or aux contacts).

Of course I could be wrong, my Square D QO catalog only goes back to 1960.:)
 
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rt66electric

Senior Member
Location
Oklahoma
update and review

update and review

Managed to get another look and pull the breakers and observe the bus stabs..

basically I'll use odd numbers only for stab/breaker##ss

fromm the meter Approx 8-10ft to main lugs 240 3ph wildleg MLO
TOP HALF
breaker 1 3>> Phase A_C 70amp factory made sub main feed --feeds lower half of panel
breakers 2 4>> phase A_C 20 amp g.p circuits
slot 5 A-phase
slot 7 C-phase
slot 9 ONLY B_phase in panel
slot 11 A-phase
slot 13 C-phase

LOWER HALF SPLIT BUSS phase AC factory fed from 70 amp from above

remaining slots 17 thru 25 are typical a-c phasing

however

the are (2) ac compessors fed from upper half using up the only B-phase slot

the next idiot used C-C-A phase oneleg fromthe upper bus and two legs from the lower bus ?????? to feed the MIL portion. The subpanel Is fedfrom a 3pole60 off a 2pole 70(factory sub-main); thus doubleup a leg. In esscence the whole house is majority fed from the 70amp 2pole submain

I also noted a spare/replacment buss/stab lying in bottom of the panel

The original main service entrance condutors appear to be either 1/0 or 2/0 tinned strands copper
It has worked fine for years?
There are several obvious "hack"modifications throughout the years that need to be attended to.

Now for the big ??? what would you do to remedy this cornumdrum ??? what would you give a estimate to do what??

??now, how do you post picts???
 
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rt66electric

Senior Member
Location
Oklahoma
1st try at adding pics

1st try at adding pics

P4010115.jpg
 
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