Should I upgrade service?

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  #1  
Old 07-29-17, 12:33 PM
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Should I upgrade service?

Hello to all and happy Saturday! Sorry for the long post.
I am trying to decide if I should I upgrade my service?
I currently have a 100 amp Square D QO panel with 20 full spaces. It was installed about 30 years ago.
Only grounded to copper cold water pipe. No rods.
I also have a small 50 amp Square D QO sub panel with 6 of the 8 spaces taken.
The house is a 1700 sf 1950's cape in Baltimore City.
Aluminum #2 SEC.
I have never had the main breaker trip.
Last week it was in the upper 90ís and everything was running but no trip.
The stove, furnace, and dryer are gas.
My loads are (amps taken from device label):
1-1/2 ton A/C only, 12a 240V including air handler (upstairs)
2-1/2 ton A/C 18a 240v
Gas furnace 10a 120v
Electric water heater 23a 240v (5500 watts)
Pool pump 12a 120v
Refrigerator
Dishwasher
Freezer
Sump pump (1/3hp)
I donít know if this enough info to do a load calculation.
I may sell it in the next few years so I donít really want to upgrade to a 200 amp service unless I am pushing the 100 amp or it is a selling point.
Thanks for all of the info and help!
Jim
 
  #2  
Old 07-29-17, 12:38 PM
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I wouldn't upgrade it just to make a selling point. If you don't need it, leave it as is.
 
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Old 07-29-17, 12:57 PM
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Curious.... why isn't the water heater gas too ? That's one of the biggest power hogs.

In looking at your list of loads.... you're running very close with a 100A service.
Any more loads added and you would definitely need to upgrade.
Without the water heater it would be fine.
 
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Old 07-29-17, 01:26 PM
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The gas furnace was replaced with a direct vent type so it no longer vented into the chimney.
The chimney is on the outside of the house. The flue gas from the waterheater cooled before it made it to the top so it would come back into the house.
The fix at the time was to install an electric one.

Anyway to figure how close to 100 amps I am?
 
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Old 07-29-17, 01:53 PM
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12A - upstairs A/C
22A - downstairs A/C and furnace blower.
23A - water heater
6A - pool pump
---------
+/- 63A @ 240vac.

They could be on all at one time before all the other smaller loads.
 

Last edited by PJmax; 07-29-17 at 02:28 PM. Reason: load corrected
  #6  
Old 07-29-17, 02:09 PM
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I think you are fine unless you are planning a large addition or a hot tub, but a demand load calculation is the best method .
 
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Old 07-29-17, 02:25 PM
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Hi Pete,
Would the pool pump be 6A @ 240v?
 
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Old 07-29-17, 02:29 PM
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Yes.... corrected my post.
 
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Old 07-29-17, 02:34 PM
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Thanks Pete.
Do you think I am too close to 100 amps before all the other smaller loads are accounted for?

How is a demand load calculation performed?
 
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Old 07-29-17, 03:13 PM
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I agree with the others, since you haven't had any issues with tripping, I wouldn't worry about upgrading it. You'll never get the money back when you sell. It sounds like the panel is in good condition.
 
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Old 07-30-17, 02:49 AM
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Does anyone know how is a demand load calculation is performed?

The main panel is only grounded to the copper water line right by the panel. I guess this was to code in the early 80's.

Should I install ground rod/rods?
 
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Old 07-30-17, 06:45 AM
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Thank you Ray. Someone else up early.

Any thoughts on the grounding?
 
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Old 07-30-17, 07:22 AM
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You need at least one ground rod. Whether you need two is a gray area. There is a way to determine if one is enough but it requires non DIY methods. Some will just use two ground rods to cover themselves. Some will ask their electrical inspector.
 
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Old 07-30-17, 07:25 AM
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Your house is grandfathered, except ...
1. If you add any new circuits and need a permit, the inspector may requre that you add ground rods.
2. When you sell, the buyer may make his offer subject to your installing ground rods although you can negotiate back and forth on this.

Ground rods must be at least 8' and pounded in all the way. If there are two they must be at least 6' apart. Use a #6 copper wire connecting them to the main panel (where the first whole house disconnect switch or breaker is) ground bus (terminals trip).
 
  #16  
Old 07-30-17, 11:21 AM
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Thanks to all that have replied!

I did a quick test.
I turned on everything in the house. I used a clamp on amp meter and measured some of the hot wires in the main and sub panel.
I also measured the two main hot wires.

All of the HVAC is in the sub.
I only measured 14 amps on each of the hots for the sub. I thought it would be higher.

I measured 62 amps on one main and 73 on the other.

There are probably a few small items like lights that weren't on but I feel safe with those readings.

Please correct me if I am wrong.

Neutral bar bonded to the panel.
The wire from the rods goes to the neutral bar.
Run another wire from the neutral bar to the copper water line where it enters the house.
Continue that wire to the gas pipe.

Anything I'm missing?

Thanks again for all of the replies.
 
  #17  
Old 07-30-17, 11:37 AM
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In the main panel only.... the neutral and ground are the same bar.
So... yes..... the neutral bar is bonded to the panel.

The grounds go to that same bar.

"Continue that wire to the gas pipe."
NO...... do not connect anything to the gas line without checking first. In most areas...like where I live.... the gas service is not routinely bonded to the electric panel.

Only grounded to copper cold water pipe. No rods.
Isn't the panel already connected to the water supply ?


Your current readings are fine and the panel is fine.
 
  #18  
Old 07-30-17, 11:47 AM
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I will check on the gas line. I know in Baltimore County it has to be bonded but I am in the city.

The panel is connected to the cold line but it is about 40' from where it enters the house.
I thought I read it was supposed to be at the entrance prior to the shut off. Maybe I read it wrong.
 
  #19  
Old 07-30-17, 05:53 PM
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The location of the ground changed. Before you could hit almost anywhere on the cold water . Now you need to be within 5 foot of where it enters the house.

You can
 
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Old 07-30-17, 05:54 PM
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You can bond the hot, cold and gas all at the water heater.
 
  #21  
Old 07-30-17, 07:54 PM
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Electric water heater.

The gas line enters at the same location as the water line so I will bond them there on my side of the gas meter.

Does the hot have to be bonded to the cold?
 
  #22  
Old 07-30-17, 08:08 PM
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Unless it has changed Baltimore City does not allow homeowner permits or work. Only licensed contractors.
 
  #23  
Old 07-31-17, 04:28 AM
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Yes I understand.
I just try to educate myself prior to hiring a contractor.
 
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Old 07-31-17, 07:46 PM
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What area is the house in ?
 
  #25  
Old 08-01-17, 05:21 AM
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The house is near Overlea.
 
 

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