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vtfan99 03-29-2006 10:14 AM

Adding New Circuit to full breaker box my breaker box is completey full with no available space for a new circuit. Additionally, I only have 150 AMP service, which I think is unusual for a new home ("cookie cutter" home)...isnt 200+ normal?

So, how do I go about adding a new circuit given this situation? Do I need to upgrade my service to 200 AMP? Or could the builder have just thrown a 150AMP master in the box to save a few bucks and simply replacing this with a 200 AMP one would work? Obviously I would need an electrician to do this, but is there a way to test without having to call an electrician? Will the power company know this?

Any other things to check that I've missed?

Thanks for all your help.

Square Eye 03-29-2006 01:15 PM

According to code, the minimum requirement for a residence is 100 amp service. There may have been a sale at the electrical supply house on 150 amp breaker boxes at the time of your homes construction. Seriously, builders are constantly looking for someone to do the job cheaper and as long as the electrical inspector keeps passing homes with 150 amp services, there will be 150 amp services on homes. Even if you upgrade to a 200 amp service, you will still have to specify that you want more room for circuit breakers. 200 amp panels are cheaper in the 30 circuit configuration. Your contractor will most likely buy the cheapest panel he can find.

It may be that you could possibly use "piggy-back" breakers. According to code though, they need to be the same brand as the panel or at the very least, specified for the brand of panel you have now. Piggy-back breakers install just like the original breakers. The difference is that piggy-backs have 2 breakers built into 1. So, you could add a circuit for every piggy-back you use. Check for availability, and consider how much wire you want in your panel. You may want to consider a sub-panel in your garage or basement.

A sub-panel wires into your main panel and is fed with a 2 pole 240volt breaker. Then you can add circuits in that panel.

Personally, if I were only adding 1 or 2 circuits, I'd do the piggy-backs. Adding 8 to 10, I'd do a sub-panel. A large addition with a separate or a much larger cooling system or a garage with a lot of woodworking equipment or welders, I'd consider a larger main panel.

A qualified electrician can walk through your home and calculate the minumum requirement for an electrical panel. A home in the building stages is not the same as a home in use. You may have a higher power requirement than your neighbor, maybe less.

Tom in KY, recommending a professional to look at your situation. It would be worth a $100.00 to know exactly what you need.

vtfan99 03-29-2006 02:07 PM

Thanks for the reply. I will be calling an electrician in the near future....definitely agree about spending a little money to find out exactly what I need before mucking around in something Im not familiar with.

Lessthanzero 01-06-2009 04:37 AM

Echo the comments of Square. I had the same situation, sort of. I had a (new) 200 amp breaker panel when moving in, but only 100 amp coming into the house. I had an eletrician (and the power co) do a power up to get me to 200 amp.

My secondary issue was that my breaker panel was full and I needed some dedicated circuits for my hobbies. Installing piggy back breakers was easy enough, but it is a quick job, and it may be better to have a qualified electrician do it. The risk/reward of getting electrified is a personal issue...

kok328 04-04-2009 09:39 AM

Depending on the type of breakers you have and whether or not you need a dedicted circuit, you can connect two circuits to one breaker. They are designed to allow for this application (not the set screw style).

ohmy 01-26-2010 06:20 AM

In this situation a sub panel is needed. In many jursidictions that are outlawing the piggyback or tandem breakers. Here in Atlanta Electricians are being required to add a sub panel.

Wuzzat? 01-26-2010 10:18 AM


Originally Posted by Square Eye (Post 2290)
It would be worth a $100.00 to know exactly what you need.

This is a problem about
Expected value of perfect information - Wikipedia, the free encyclopedia

The EVPI for an online home heat loss calculator [Manual J] seems to be $49, or at least that is what people are willing to pay.
The HO still has to fix the HVAC problem if there is one, but at least he/she has some assurance that the fix will work and give comfort and energy savings in the future.

I guess I'd first run through the few possible options listed here and allow for reasonable expansion. Then have several electricians bid on these same options.
To get five over-the-phone bids you might have to call two dozen contractors. If nothing else, you may be able to narrow the list of candidate contractors.

For each option, your phone or in-person bids should look something like this

relative cost
with a and f being outliers and c being the true cost.

Little Story

We had a screened porch done by people who were licensed, etc., etc., blah, blah, blah. The wiring conduit didn't look right so I looked in the NEC and it said the packaging tells if it can be used in a dry, damp or wet location. Well, the packaging was gone, so I found identical stuff in a store with the packaging intact and it said "dry location."
I also tested for GFCI protection using a small incand. bulb. It failed that test too.

Comes inspection time.

I can see the inspector looking at this conduit and shifting his weight from one foot to the other. Clearly the guy had a dilemma. I then asked him if this conduit wasn't for a damp location.

Well, that broke the dam. He wrote up that electrician from A to Z and the guy had to come back and redo.

Why did the inspector have a dilemma? Maybe this \/ from Wikipedia

"Regulatory capture is a term used to refer to situations in which a state regulatory agency created to act in the public interest instead acts in favor of the commercial or special interests that dominate in the industry or sector it is charged with regulating. Regulatory capture is a form of government failure. . ."

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