Tandem Breakers

[ikabod]

I'm planning to add sub panel but the budget is tight, I read someplace to replace those existing breakers and use tandem breakers, is this a good idea?

[BuzzKill]

As long as you are not exceeding the rated capacity of the breaker or the sub panel it should be perfectly fine.

[ikabod]

As long as you are not exceeding the rated capacity of the breaker or the sub panel it should be perfectly fine.

Thanks!

[omzig]

There is also a limit of 40 breakers in any residential panel, with tandems counting as 2.

[Photovor]

There is also a limit of 40 breakers in any residential panel, with tandems counting as 2.

wouldn't that just be for a 100 amp panel?

[omzig]

wouldn't that just be for a 100 amp panel?No it is for any residential panel. Actually it is 42, not 40.

From the National Electric Code:
"Not more than 42 overcurrent devices can be installed in any one cabinet." (NEC 408.15)

[Photovor]

No it is for any residential panel. Actually it is 42, not 40.

From the National Electric Code:
"Not more than 42 overcurrent devices can be installed in any one cabinet." (NEC 408.15)

I guess I'm thinking of available slots. I know 100 amp panels usually have less slots than 200 amp panels, etc... But I guess this can also depend on manufacturers and cabinet types.

[eswets]

I don't think that it is a good idea unless you have an electrician wire them, or you are familiar with house circuits. I've had to repair many electrical problems (burnt up outlets) that almost burned the house down because of the tandem breakers. If using the tandems you just can't start moving breakers and wires around without keeping the wire on the same phase or make sure that the neutral wire is dedicated to only that circuit, not sharing with another circuit. There are 2 simple mistakes people make doing there own electrical (and lots of electricians) that can cause real problems and even hurt someone. And installing tandems the wrong way is one of them.
Eric

[Photovor]

You just don't want to be replacing 220v appliance circuits, and putting them on tandem breakers, that's how you can get messed up with phases, etc, plus those appliances must have their own dedicated double pole breaker. As for moving existing circuits onto tandem breakers, this would be no problem, because you already have existing neutrals for the 2 circuits you're combining. You wouldn't be sharing a neutral for two separate circuits in the first place.

Just be sure that the tandem breaker you are using does not exceed the amperage capacity of the lowest amperage circuit you're combining. For example, if you have a circuit that is 14AWG, 15Amp, and a circuit that is 12AWG, 20AMP, you MUST use a 15 amp or less tandem breaker. This is where replacing things and not paying attention gets to burning the house down.

[taybrynn]

A full size panel with 40 slots won't take even a single tandem breaker ... at least the SquareD units won't.

Most subpanels, being smaller than 40 slots ... have a certain number of slots for tandem breakers.

[omzig]

A full size panel with 40 slots won't take even a single tandem breaker ... at least the SquareD units won't.

Most subpanels, being smaller than 40 slots ... have a certain number of slots for tandem breakers.This is true for all newer panels , but there are older Siemens 40/40's that would take tandems even though the label says that you shouldn't use them. There are also older tandem breakers (not maked "CTL") that will go in panels that are not designed to use them. I discovered this when my nephew bought a house that had a 40/40 panel with 6 tandems installed. The useless home inspector that he hired totally missed this (among other things). To make matters worse, Five of the six tandems were on the same leg of the service, making for quite an unbalanced load. I installed a subpanel for him and removed all of the tandems.

[Photovor]

There should be one common summary to all this. If you get to the point where you think you need to start using tandem breakers, install a sub panel. It's safer, code-worthy, and chances are, once you have the extra space, you'll find things that you'll want to put on their own breakers.

[ikabod]

To sum up, you guys are recommending to avoid tandem breakers and have sub panel instead.

How much do you think a sub panel will cost me (ball park figure). I called an electrician to put on 60Amps sub panel with 8 breakers and it's charging me $1,200 that's why it scared the heck out of me of putting up sub panel.

[omzig]

There's nothing wrong with using tandem breakers if your panel supports them. If your panel is marked "Class CTL" (near the UL label) then you must use CTL tandems (most are). The tandems that are marked "non-CTL, for replacement use only" will fit in a CTL panel but you are violating the NEC by using a breaker that is not approved for use in the panel.

What type of panel do you have?

[ikabod]

I will post a picture of my panel soon as i got home.

[taybrynn]

No, it's for any panel.

For example, my 200A panel has 40 slots ... and none can take a tandem breaker.

If I had a 200A panel with 32 slots, 8 would probably take/allow tandems ... so if I used tandems in those 8 slots, I'd still have only 40 circuits in the panel and no more.

[Photovor]

To sum up, you guys are recommending to avoid tandem breakers and have sub panel instead.

How much do you think a sub panel will cost me (ball park figure). I called an electrician to put on 60Amps sub panel with 8 breakers and it's charging me $1,200 that's why it scared the heck out of me of putting up sub panel.

That seems pretty high. In the city here, homeowners must use a licensed and bonded (through the city) electrician to do any electrical work. I had an estimate once to change out our service entrance to 200A. The figure was under $300 for all the work (this was 2 years ago). Which I know that is a great price.

The parts on a subpanel, breakers, and minor wiring should cost under $150 (I've just priced this out at lowes). I can do the wiring myself, etc, however when it comes time to inspect and sign off on the new sub panel, that's where I'd run into trouble of me doing it. I'm not aware of what a 'normal' going rate is for electrical work, but I'd get at least 5 quotes from different companies.

You might offer to buy the parts yourself and mount the new panel where you want it, in order to save on the labor costs and any markups they might be hitting you with.

[Jeff Millard]

Gents,
Check with your community permitting office. Many communities allow the homeowner to make all electrical upgrades to a property. That doesn't mean you get the permit and your cousin "Joey The Hack" can do the work... It means that you, the homeowner, can make any and all improvements including complete new services to your residence. I would suggest you stick to it if you try this approach, as the inspector will ask questions and you should be ready with acceptable answers.

I did my own 200Amp service using this type of permitting. Although I work for the electric company, the inspector had no idea and probably wouldn't have given me a break had he known. The internet is loaded with sites frequented by Licensed Electricians and Engineers who are willing to answer all your questions about doing these things.

My source for the best information I needed to get the job done right was the inspector himself. I hung the box on the wall, wired the secondary to the meter pan. Then I installed the conduit and weatherhead and wired the copper to it leaving 3' for connection to the drop. Then I called for the inspector. I wasn't home but Dawn handed him the phone. I asked him what was needed for specific things like grounds to water pipes and earth. I also described how I would connect to the circuits in the home and remove the old panel. He gave me pointers and I followed his direction to the letter.

It passed muster on the frist final, and i had never done anything that major in my life.

My appraisals were in the thousands of dollars for the work I did myself. All told everything cost me less than $500 including the wiring for 10 dedicated circuits to the display...

Jeff

[NogginBoink]

I second jeffmill's comment. I replaced a 200amp breaker box myself in my home with permit.

I first called the inspector's office and found out when the inspector is usually in his office (since, let's face it, most of his day is spent out in the field). I went in and said I want to replace my own breaker box and asked what, in particular, he'd want to see when he did the inspection. He told me he was going to look for this, this, this, this, and this.

I wrote down those five items he said he was going to look for. When I did the work, I made sure to do those five items.

When he came to do the inspection, he looked at those five items, gave me the green tag, and told me I was the only inspection all day that had passed.

In short, if you make friends with the inspector up front, and demonstrate that you want to do the job safely and correctly, you'll make an ally of the inspector. If you try to dodge the rules and stay under the radar, you're setting yourself up for a confrontation, and in that type of confrontation, one person has all the power. (And that person isn't you.)