Question for the Electricians

[Fe2o3]

Hope it's an easy one.
I plan on tearing down my existing detached garage and rebuilding on the same slab. The old one is fed by a 20a service off of the house. My plans are for a 100a service panel. It's just me there and I can only picture my peak load being the welder, compressor, and AC running as well as lights and maybe a radio.
My question is can I just double lug the meter at the house and run a set of wires to the garage? The house is already 200A. Will the feed wires from the transformer handle it? Will the meter handle it? Or should I have a new meter installed on the garage to avoid any overheating? Recommendations?

 

[Fast Orange]

There is a way to do what you're talking about,but it will involve new service entrance cables,new meter and a pair of service rated disconnects.If your power co will allow it,it will be cheaper to put a separate service on the garage.
Is there a reason why you can't simply run the garage panel off of your house service as a sub-panel? Odds are that you won't use over 200 amps between the house and shop at any one time(unless you have electric heat or some other heavy use of power),so that would be the most practical solution.

George

 

[hdroadkingc]

If you want it to meet code, you cant double lug off the meter base. You can add a breaker for the garage out of the panel at the house if you have room and you can get to it.

 

[gboezio]

Well, just add all the breakers you have on your house electric box, single count for half, then 200-(total amps)=what's left for the garage. You'll need a pretty beefy wire and these ain't cheap, so I would check on the power company like said above to check for what's come out the best and at what price.

 

[Fe2o3]

Thanks guys,
I suppose it'll be easiest to add the service at the garage and just make it 200A. The whole house is electric everything and the family ain't afraid to use it! Stove oven dryer,AC, water heater pumps... energy hogs all. This just sounded feasible (easy), as I thought that double lugs could be purchased for just such an appication. I was worried about the service entrance overloading.
Again, I appreciate the responses.
Moderators, sorry for placing this in the wrong forum. Wasn't paying attention.
Dave

 

[gboezio]

Yeah better safe than sorry, wife in full squid style cooking, kid in shower, you welding 1/2" steel in the garage, all heaters on, dryer, fridge, garage fridge running from the beer you just took, etc..
Well wires will be frying

 

[alia176]

Wouldn't it be straight forward to simply add a 100 amp breaker in the main service panel and then run #3s out to the garage 100 amp subpanel?

 

[gboezio]

That would leave 100 amps for the whole house, witch is very little for a modern house, If all the appliances work at once while he's welding 250 Amps can be drawn from the wires and this can start a fire. Not to mention the electrician and insurance company that would never let the total breaker load past the wires capacity.

 

[cw_racefan]

You can't simply add up breakers to know how much capacity you have left. Chances are right now if you add up all your breakers you probably will come up with several hundred amps. You (or someone) needs to do a "demand load" calculation to determine your needs. You may be ok without a service upgrade, but there's no way to tell without doing the load calcs.

 

[wmonroe]

I am having a separate service put in my garage. I am responsible for getting (and installing) the entrance cable, meter socket, and panel and then having it inspected. Once it is inspected the power company comes out and runs the wire from the pole to my garage and makes the connections. They told me they don't charge to do this so for me it was way easier just to get the separate service and not worry about overloading my house service.
Will

 

[Tscott]

just put a 100 amp breaker in you house panel and run 1/0 wire to the new garage box. house panels are rated WAY under what they can handle. Remember, the ratings for electrical panels are set by fire codes. These panels are designed to hadle short circuit currents. You can easily run a 200 amp panel at 250 to 300 amps safely. You will never get that panel running that hot though remember the equipmetn in you home will nto all run at the same time, they will switch on and off independent of each other. This is called diversity and it simply means that even if you ahve a connected load of 200 amps, usually at any one time you will only have 50% to 40% of it running.

Good Luck

Tom

 

[cj7jeep81]

That would leave 100 amps for the whole house, witch is very little for a modern house, If all the appliances work at once while he's welding 250 Amps can be drawn from the wires and this can start a fire. Not to mention the electrician and insurance company that would never let the total breaker load past the wires capacity.

maybe i'm missing something, but how is this possible? if the panel for the house has a 200amp main breaker, wouldn't that just trip and shut down power to everything?

how would he be putting the load past the wires capacity (assuming the wires to the house are rated for 200 amps, and the wires for the breakers including the 100 amp sub panel are sized for their respective loads)?

 

[Tscott]

maybe i'm missing something, but how is this possible? if the panel for the house has a 200amp main breaker, wouldn't that just trip and shut down power to everything?

how would he be putting the load past the wires capacity (assuming the wires to the house are rated for 200 amps, and the wires for the breakers including the 100 amp sub panel are sized for their respective loads)?

Yes you are correct, the breaker would trip. The reality of most houses is that you are not pulling more than 50-60 amps at your highest load. If you were to exceed this on a regular basis then your electric bill would be $400 a month. Even with a full garge and seperate AC load in there chances are the largest load that panel will ever see is around 150A TOPS with everything running and My guess would be the average will be under 100A. You would need a major AC and a serious welder to pull enough amps on that panel to cause a problem.

If you don't believe us then get a cheap amp probe and put it on the service wire to the house and check the amp draw, you will be surprised at how low it actually is.

Tom

 

[bigdav160]

If you were to exceed this on a regular basis then your electric bill would be $400 a month

Come down to Texas where $400 is a cheap electric bill.

 

[gboezio]

I forgot to check where you guys are from, here in Canada, an electric heated house can draw 50 Amps out of 200 only for heating on a cold night, take off most of the electric heating breakers, you may have enough room to save 100 amps for the garage.

 

[thefairlaneman]

I hooked into the main panel breaker that serves my house and then used a safety pull out fuse box attached 2 feet away before I buried the cable to my garage. Once inside I connected up another sub-panel and also used a separate ground rod for safety It has 2 220 circuits and 4 15 amp circuits. Did it 7 years ago with no problems. I do sujest using the dielectric grease when hooking into your main breaker. This connection has to be tight and secure. If anything overloads in my shop the pull out fuses will blow before it burns up the main breaker. Be sure to remove the meter first.

 

[RPH]

Here in Michigan, for Edison to install new transformer to feed barn for seperate service $1800.00. Does not include wire to building. But they were willing to wire to existing transformer 450 feet away, underground for only $10.00 per foot.

 

[RMF]

I am an electrician by trade. When I built my garage (20 x24), I sized my panel for a 6hp/60 gallon single-stage compressor (20a/240v), a 120v welder (20a/120v), a four-post lift (30a/240v), 8 two-tube flourescent lighting fixtures on 1 15a circuit downstairs, 2 two-tube flourescent lighting fixtures on 1 circuit in the loft, and 3 20a receptacle circuits with the maximum 12 reeptacles per circuit (I sized it this way to allow for expansion when I finish the loft into a rec room). The 100amp subpanel is fed from a 150 amp main panel in the house from a 100 amp double pole breaker. I build race engines and do steel fabrication on the side, and have never had a problem with power delivery. The calculations are figured per National Electrical Code. There are certain allowances for incidental loads and other calculations for continuous loads to determine the size allowance for your sub-panel. For instance, my house has gas appliances and therefore does not load the panel as much as a house with, for example, electric heat and an electric hot water heater. I can therefore use more for the garage. The best thing I can suggest is for you to contact a local electrician and ask him if your house panel will handle what you want to do. It will all depend on what is already on it.