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Garage wiring estimate

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I have two estimates from experienced electricians to set up a 20 space 100 amp box out to a new constructed 25 X 50 ft attached garage. The problem is the main box in the house is almost 100 feet away, so it's a lot of wire, and I want it run in conduit. The first estimate was $1000 and that was without running it in conduit. The 2nd estimate was $1300 and that was with conduit. This is just running the main wire out, setting up the box, and installing a few outlets to get me started. It's not wiring the whole garage. Both electricians are independent and not part of a large company. I'm smart enough not to try to do it myself becauce I don't want to burn the garage down. What do you think of these estimates? I was hoping for cheaper, like $600 - $700, but maybe I'm behind the times.

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Doing what you describe is stone boat simple and can be easily and safely done with the help of available DIY books. If you buy the materials from an electrical supply house rather than a big box store you may pay a bit more but I've found the counter men to be a font of knowledge and only too glad to help with material selection and helpful hints and advice...........Bob.

Edited by Bhigdog (see edit history)

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The immutable law of electrical components is that once you let the smoke out you cannot put it back in..............Bob

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Have you looked at a seperate meter - service for the garage???? that way you can get a lot of juice and not worry about power drain for the long run.

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I have two estimates from experienced electricians to set up a 20 space 100 amp box out to a new constructed 25 X 50 ft attached garage. The problem is the main box in the house is almost 100 feet away, so it's a lot of wire, and I want it run in conduit. The first estimate was $1000 and that was without running it in conduit. The 2nd estimate was $1300 and that was with conduit. This is just running the main wire out, setting up the box, and installing a few outlets to get me started. It's not wiring the whole garage. Both electricians are independent and not part of a large company. I'm smart enough not to try to do it myself becauce I don't want to burn the garage down. What do you think of these estimates? I was hoping for cheaper, like $600 - $700, but maybe I'm behind the times.

As an electrician I can tell you that is a fairly decent price. Two things I will comment on,

1. Go with a 200amp service on a garage that big if it is also a shop. If it is just for storage and all you will have is lights then 100A would be adequate but not ideal.

2. Definately go with the conduit.

Good luck, sounds like a nice size garage.

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Here in the UK it is actually illegal to do an installation like that yourself. It must be, at the very least, checked by a certified electrician. Which is a real nuisance.

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Here in the UK it is actually illegal to do an installation like that yourself. It must be, at the very least, checked by a certified electrician. Which is a real nuisance.

It's getting that way here. In many districts the work may be done by the owner but it must pass an inspection. Some places there is little regulation............bob

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In Australia and New Zealand where the power is all 240 volt, all electrical work must be carried out by a registered electrician. It is illegal to do it yourself. 240V kills.

If the power supply to your shed is going to be underground you could install the conduit yourself with a draw wire through it so the electrician can pull the cable through and that would lower the price quite a bit. Feed the draw wire into each length of conduit as you are installing it.

David

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I too, am an electrician and that's not a bad price. However, the main feed between house and garage is pretty basic DIY stuff. You should be able to get a "Homeowner's permit" which will allow you to do the bull work yourself.

If you don't plan on future trenching in the area of the cable use direct burial conductors.

Just so you know, the system in the garage will be considered a sub-panel and will require a separate neutral and ground, so you'd be burying 4 wires.

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Barry,

When we poured the floor we pounded a metal rod into the ground that you buy at Lowe's for the ground for the subpanel. The concrete floor was poured around it. It's about a 4 foot rod and we got it about 2 1/2 - 3 feet pounded into the ground. Correct me if I'm wrong, but I'd be running three wires. Hot, neutral, and ground. The box will be grounded to the rod. We're running the main feed wire on the basement (of the house) ceiling, and through the attic of the existing two car garage to reach the new garage addition. We're not running it outside.

Question. I see you can buy main feed line that has the three wires in it at the big box stores for about $1.50 foot. However it seems the electricians I've talked to want to buy each wire seperate. Any reason for this?

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Are you digging the trench or are they? If they are doing the digging thats a "really" good price.

If you are not comfortable doing electrical work don't even consider it. If you have a qualified friend or neighbor to guide you then thats OK. You do the labor but they check in and make sure its being done right and the correct materials are purchased.

If your soil is primarily rock free like say clay or sandy soil you do not need conduit assuming the area is not being driven over by vehicles such as a driveway. Even if you have a few rocks just insure they are cleared away from the wire when backfilling. Direct burial wire is made for direct burial and can withstand cuts in the insulation from normal pressure from settling, freezing/thawing etc, but you always want extra precaution such as conduit any time the soil will be compressed by a vehicle or whatever.

On the single conductor vs grouped wire question. When running in conduit, typically its less expensive and easier to pull individual conductors. If individual conductors are used for direct burial they should be of the type that are a group of 3-4 wires twisted together so it lays like a single cable just without an extra outer protective sheath.

Edited by JZRIV (see edit history)

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Barry,

When we poured the floor we pounded a metal rod into the ground that you buy at Lowe's for the ground for the subpanel. The concrete floor was poured around it. It's about a 4 foot rod and we got it about 2 1/2 - 3 feet pounded into the ground. Correct me if I'm wrong, but I'd be running three wires. Hot, neutral, and ground. The box will be grounded to the rod. We're running the main feed wire on the basement (of the house) ceiling, and through the attic of the existing two car garage to reach the new garage addition. We're not running it outside.

Question. I see you can buy main feed line that has the three wires in it at the big box stores for about $1.50 foot. However it seems the electricians I've talked to want to buy each wire seperate. Any reason for this?

They wouldn't be running individual conductor in your house unless they were an approved cable enclosing the conductors.

You had better check with your local authority, but I believe sub=feed cable (4 conductors) will be required. You need to find that out before you do anything.

If they were running pipe through your house, that's an especially good price.

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Per the National Electrical Code: For 240-volt used as a sub-panel you will need 4 wires. 2 - hots / 1-neutral / 1-ground with the correct rated cable, be it direct buried, overhead, or in conduit. The reason you carry the additional ground wire is that your neutral (white wires) and bare ground wires need to be separated at the subpanel via separate / different terminal blocks. On the main panel they use the same block. The neutral bonding screw that comes with the panel is not used on a subpanel installation. Only at the main panel or 1st disconnect switch is the neutral allowed to be bonded.

You can not use the gray covered cable (SE / SER) in a underground conduit as it is not rated for water. Your ground rod sounds like it may be to short? I would take a resistance reading just to verify. The separate ground rod is required on electric services that are in out buildings, etc. Not attached to the structure your main service is serving. Also some municipalities require an electrical inspection. If you decided to do your own wiring have an electrician check it out. Not only can you be killed you can burn it down including loss of all the contents.

The price they quoted sounds reasonable however 100' away is a long distance and will more than likely require a larger wire (voltage drop needs to be calculated verses load). 100 amps isn't much for a garage. A 100 amp breaker trips at 80 amps.

Edited by Ron Green (see edit history)

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DAVIDAU

120 volts here in the USA kills more people than any other voltage. Yes it is less lethal but it is sooooo common.

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Why would 100 amps not be enough? The one electician I spoke with put it this way: how many things are you going to run at the same time? I might have 20 power tools, but you can only use one at a time. Lets take a worse case scenario: In the garage there will be a large two stage compressor that draws 25 amps, a glass bead machine with a small electic fan motor on it, a bunch of florescent ceiling lights, a garage door opener, a small fridge, and then a wide assortment of power tools. If I ran the compressor, the glass bead machine, all the lights, the fridge, and opened the garage door while using a drill press, is that going to be 80 amps?

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Here in VA, a homeowner is allowed to do wiring on his/her own property without being a certified electrician. This really is dirt simple wiring, and I recently did exactly this wiring in my garage - which is nearly 500 ft from the house. I did the voltage drop calculations and ended up using 4/0 USE cable (direct burial cable) to minimize the voltage drop.

If you are not comfortable doing this wiring, you can string the wires and install the boxes yourself and just have the electrician make the connections. That should save a few dollars.

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Why would 100 amps not be enough? The one electician I spoke with put it this way: how many things are you going to run at the same time? I might have 20 power tools, but you can only use one at a time. Lets take a worse case scenario: In the garage there will be a large two stage compressor that draws 25 amps, a glass bead machine with a small electic fan motor on it, a bunch of florescent ceiling lights, a garage door opener, a small fridge, and then a wide assortment of power tools. If I ran the compressor, the glass bead machine, all the lights, the fridge, and opened the garage door while using a drill press, is that going to be 80 amps?

I did not say 100 amps may not be enough (80 amps actually). Add an electric welder, a lot of lighting, air compressor, AC or electric heat for a separate room possibly, etc, etc you could be pushing it. I don't have a crystal ball to know what you are visualizing.

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Why would 100 amps not be enough? ?

100 A will be more than adequate. You are exactly right, it all comes down to actual demand of the equipment that will be used. With 100A you will still have excess capacity for future loads not yet envisioned.

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The only other thing to consider is that it's much cheaper to run 200A now than to upgrade the 100A to 200A later.

I'd get a quote on both, then make the decision.

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This is why you have to have friends. I have plumber friends, lawyer friends, and electrician friends.I recently asked my electrician friend to put power into my small barn. 2 four foot fluorescent fixtures, 2 outlets with GFI, underground conduit, wiring, and knocking the hole in my house foundation. My cost, including materials and installation, was $20 bucks, plus lunch.

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Maybe I am missing something here. If he is running this sub box off of his existing house circuit, then you won't want to pull anymore than 100 amps for a sub box. Am I right in thinking you wouldn't want to try a 200 amp sub? Seems this would be to taxing on the existing house circuit. My garage is a 100 amp sub off of my house circuit. Am I thinking wrong?

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I just thought of something. Down the road, I may want to install a ceiling mounted commercial type electric heater. Garage is 1250 sq feet , but i might install a thick plastic "curtain" in order to heat just 1/2 of it. Anyone have one of those currently installed? How many amps do they draw? I know one thing I don't want is a natural gas heater with a flame. A friend has wall mounted ones where you can see the flame just standing in front of it. I don't think having an open flame in a garage with chemical vapors (gasoline, laquer thinner, carb cleaner, ect) is a good idea.

I may have to do more research here and hold off until spring on doing this wiring project. I want to do it once and do it right.

I appreciate everones comments and suggestions.

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