Out of Supply Space

Reply

  #1  
Old 03-09-07, 01:24 PM
Member
Thread Starter
Join Date: Jan 2005
Location: USA
Posts: 119
Out of Supply Space

I was going to have a 2nd zone HVAC system added to my house but ran into an electrical problem. I was checking the supply available for the new unit and discovered that there are no available slots for the new circuits. What can I do? Do I need to install a new set of bars in the breaker box with more space? Can I replace the circuit my current HVAC system is on with a larger amp circuit and install a subpanel from that circuit to feed the existing and new HVAC equipment? If so, what is a good size of that curcuit and wire?

My HVAC guy says I need a 30AMP and 60AMP circuit for the new equipment. I did a preliminary load calculation with my current system and 93Amps with 78 Neutral amps. I do have 200 AMP service. Thanks for the suggestions.
 
Sponsored Links
  #2  
Old 03-09-07, 01:32 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
There are three main ways to get more space for breakers, in order of increasing expense and difficulty:

(1) Replace full-size breakers with tandem breakers, if your panel allows it. Tell us the make and model number of the panel if you want to see.

(2) Add a subpanel. This requires moving a couple of circuits from the main panel to the subpanel if the main panel is already full. It's best to keep the larger loads on the main panel and the smaller loads on the subpanel.

(3) Replace the main panel (if the main panel currently has fewer than 42 spaces).
 
  #3  
Old 03-09-07, 01:39 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Assuming that your service can handle the additional load, and it sounds like it can, you have several options.

Your panel is most likely already a 40 space panel, so a larger panel is not an option, and it sounds like you already have all spaces full.

This means a sub panel is the only viable option. To install a sub panel requires that you free up space in your main panel for a breaker to feed the sub panel. This just means moving an existing 240 volt breaker or two adjacent 120 volt breakers to the sub panel. What I would recommend in your case is a 100 amp sub panel. I would then move six regular 120 volt circuits into the sub panel. This would allow you to place your new HVAC circuits in your main panel and would give you room in your sub panel for growth.
 
  #4  
Old 03-09-07, 01:46 PM
Member
Thread Starter
Join Date: Jan 2005
Location: USA
Posts: 119
I know it will accept tandem breakers, because I had to put one in to replace a double tapped breaker that was there when I bought the house. Just to be surehere is the info from: Cutler-Hammer, Cat No: CC2200, 2 Pole Unit, Issue # KS601. This info is actually from a sticker on the main breaker. I was hoping this was the right info so I didn't have to pull the cover panel off again. If not, let me know.

I wasn't sure if tandem breakers was something that was just OK as a fix for 1 or 2 breakers, or if If could do several of them that way. That would be the easiest way to make the space, if it won't cause any additional problems.
 
  #5  
Old 03-09-07, 01:52 PM
Member
Thread Starter
Join Date: Jan 2005
Location: USA
Posts: 119
The cover panel has knock outs for up to 30 breakers (15 on each side) but the current setup only has space for 24. If I go with the subpanel, what size wire should I use to feed it?

Another issue I forgot to mention. When looking at the system, I noticed the main ground wire is connected to a water pipe, that, if you backtrack, would eventually get back to the main supply line which goes into the ground. Is this OK (I'm guessing not)? It seems like if that ground wire energized, my entire plumbing system would energize, which could cause a shock by trying to turn on a faucet. Am I reading too much into it?
 
  #6  
Old 03-09-07, 01:56 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
What do you mean "the current setup only has space for 24?" It sounds like you can add six more breakers to your panel.

Your ground wire should be connected to your water pipe and to some other ground, usually a ground rod. The connection to the water pipes is to provide a proper ground (if the main water pip extends outside the house into the ground) and to make sure that you in-house metal water pipes are properly bonded.
 
  #7  
Old 03-09-07, 02:07 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Sorry, but you gave us the specs on your main breaker. I wanted the specs on your panel.

Your grounding sounds fine. Well, at any rate we don't have enough detail to know that it's wrong.
 
  #8  
Old 03-09-07, 03:16 PM
Member
Thread Starter
Join Date: Jan 2005
Location: USA
Posts: 119
I had a feeling those numbers were for the breaker. I'll take off the cover and find the other #'s. The cover panel has enough knock-outs for 30 breakers, but when I take off the cover panel and look at the bars, the 24 breakers that are on the system take up all the space on the bars. There is physical space for more breakers in the box, there is just nothing left to attach them to.
 
  #9  
Old 03-09-07, 08:35 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
You should not have to remove the panel cover to get the model number.
 
  #10  
Old 03-10-07, 06:10 PM
Rollie73's Avatar
Member
Join Date: Mar 2007
Location: Bras D'Or, Nova Scotia ,Canada
Posts: 173
Smile Your Grounding Query

If the grounding conductor were to become energized it would be for a very short period of time and then the breaker for the circuit that has the fault (causing the conductor to be energized in the first place) will trip. It is highly unlikely that anyone will ever get a shock from turning on the faucet even if you had your hands on it at the precise moment that the fault (short) occured because electricity always seeks the easiest path to ground and that path is through the grounding conductor
 
  #11  
Old 03-13-07, 10:10 AM
Member
Join Date: Apr 2004
Location: Ontario Canada
Posts: 1,767
In that case, you have a 24 circuit panel.
All of John's recommendations still apply, the latter two if you cannot use tandems.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes