Advice - garage requirements

[GDA]

New member here and have found this forum to be very, very helpful. This question relates to residential house in Dallas, Tx and is part of a planned remodel in Feb/Mar of next year (HVAC, new windows and 2 car to 4 car garage/shop expansion).

In researching numerous threads on 200A service, which I have and appears to have been put in during a early 90s refurb, I am trying to determine what I will need to consider for service to the garage. Current box is about half used. Garage has 1 4 plug outlet right now. :realmad:

Here are my current requirements that I have planned:

Eaton 5hp compressor - 220V 35A
MM 210, 251 or 350P - 42A or 61A draw req 60A or 90A
375 Extreme plasma - 40A
Other tools - drill press, grinder, belt sander etc - couple 20A breakers
Halogen lighting throughout - 2 20A breakers
Poker room over the shop with tv - 2 20A
Garage door and motion lights - 20A
Sprinkler system - 20A

With these requirements and in reading other posts it appears I need another 200A box for the garage right? I did some searches and service upgrades for this seems to run 1500 bucks. Should I be looking at another 200A box or am I way off base. I would like to understand this better so I can talk this though with my GC.

Thanks for the help.

Greg

[gimpyrobb]

The "guys in the know" should chime in soon, but till they do I'll give my .02. I would say 150 amp should be plenty. Seldom will you run everything at once. I have been getting away with running my "workshop" off a 60 amp breaker from the house. The box in the garage is rated @100amps, so I am searching for larger cable at the right price. Right now I just watch what big current tools I turn on at the same time. Good luck and better info should be along soon.

[MAC702]

How many arms do you have? Are you going to supervise a 3-man crew in this garage? 200A is BIG when it comes to a one-man shop.

Is it detached or attached to the home?

A 100/125A subpanel in the garage would be plenty. Higher than that, and you're at the 200A size panel anyway.

Even if you get the MM350 and are running it at full tilt (building rock grizzles or something) you aren't likely to be running much else other than lights that the same time. And as soon as the arc is off, it stops drawing. Run as big a grinder as you want...

[Sandy]

Like gimpyrobb says, unless you can figure some way to run a whole bunch of this stuff at the same time---------no need to throw money at a box you don't need. The number of breakers you want will take a certain physical size of box which just might be rated at 100 amp. Your biggest weldor requirements say you need a 100 amp box at face value but everything else says you definitely don't need a 200.

Just for giggles let's look at your 20 amp receptacle you're going to run for the sprinkler system. That will pull milli-amps while it's running. That's and insignificant load.

I'd guess your main panel for the house is only a 200 amp box isn't it?

[metalworks]

I built a new house, a few years ago I have a 200A service in my home. I put a 100A breaker in that panel ran the correct wire size from that breaker to the garage in conduit and installed a 100A panel in the garage. Ive got three 220v machines, five four tube flourescent lights, and the everyday tools. Ive never had any problems. I think 100A is plenty. just my 2 cents

[alanaker]

Ditto that... A 200 A main panel will support a 100 A sub panel for your new shop. That's what I have. The $$ cost takes a huge leap up if you go beyond that. Sounds like a neat project...

[GDA]

Hey thanks all for the responses. Garage is stand alone and 40 to 50 feet from the service at the rear of the house. From my question you can tell I am real novice when it comes to electrical. The math guy in me just added each item up at full draw to trip the breaker. I now see my error in that you need to consider capacity of the box as a function of overall actual cumulative draw by all circuits, both individually and in the aggreagate, right? So since my largest item would be less than 100A and at most all items in use will never exceed 100A in the aggregate that then determines the service. Let me know if I am following this right.

I did want to hear from others what I would be looking at if I had more that one tool running, say compressor and welder and maybe another tool since I doubt I will be the only one in the shop. When you have tools and projects, your friends are not too far away.

Thanks for the advice and I will keep researching on 100A service with enough individual breakers to fit the need. I will probably have some more questions but thanks for all the help.

And Mac702 - we grow 'em normal here in Texas with two arms and legs.

[alanaker]

I'm not an official electrical guy, but...You'll end up running probably 4 individual conduits from your house to your shop. One for the 3 heavy conductors, one for any 120V switched lighting circuits between the shop and house, one for low voltage stuff like alarm and CATV, and another for phone. Some of this you could direct bury, but PVC conduits would be better down the road. If you use #2 copper with THHN insulation, your local electrical/building inspector might allow you to use a 125 A sub panel in your new garage. Check your local supply place to see what 3 lengths roughly 70' each of #2 THHN goes for these days.... Home Depot around here sells it also. Use a 125 A breaker at both ends of the run, and you'll need another ground rod outside at the new shop tied into your new sub panel.

[MAC702]

You'll end up running probably 4 individual conduits from your house to your shop. One for the 3 heavy conductors, one for any 120V switched lighting circuits between the shop and house, one for low voltage stuff like alarm and CATV, and another for phone. Some of this you could direct bury, but PVC conduits would be better down the road. ...

and you'll need another ground rod outside at the new shop tied into your new sub panel.
Thanks for mentioning the ground rod. BUT, 4 conduits are unneeded. For one, the second circuit, regardless how convenient, will be illegal. Only one circuit allowed to an outbuilding, though you may be able to not ENTER the building with an exterior lighting circuit, if you really NEEDED to. Also, all the low-voltage stuff can share the same conduit (phone , cableTV, Internet, etc.)

[MoonRise]

Why are you running multiple conduits for circuits from house to the shop? :confused:

Now, there is usually more than one way to do something. Some are equally valid, some are questionable, and some are just not right.

Go to the main panel, put in 100A 240V breaker, run appropriate size wire in one conduit out to garage, wire goes into the garage subpanel, breakers for the garage go in the subpanel. Run the 110-120 volt branch circuits for the 'little' tools on some 20amp breakers, run the lights on different branch circuits, put in a 240V breaker/circuit for the compressor and one for the welder and maybe another one for a dust collector (wood only, don't use it to suck up sparks!). Pretty much done. Look into upsizing the wiring to allow/account for voltage drop for the distance of wiring used, especially with that big of a welder being used.

If you are using the big welder at MAX, then you may have to turn the compressor off temporarily to make sure that the big compressor doesn't kick on while you are welding. Other than that, just about everything else can probably run at the same time and not have any issues. Unless you are running like 10 different 120V 20amp branch circuits, each with a big a## 20 amp machine on it, and all of them are running at the same time, and the compressor kicks on. But then how many hands do you have or how many buddies are you going to have over at once doing heavy tool work? :waving:

All the low voltage stuff can go in a separate conduit, like MAC702 said. Even if you don't think you need all the low voltage stuff out there right now, strongly think about at least putting the conduit in and some pull strings into it while you have the trench dug. It's a lot easier to put the conduit in now than to have to go back later and redig a trench. Or just plan to do the phone, internet, etc via wireless from the house instead.

[alanaker]

Yep, 4 conduits between house and garage. Done it in 2 states. Last I knew, phone is not considered low voltage because the ringer uses higher voltage. Your mileage may vary.

[MAC702]

I'm not an official electrical guy, but....

Yep, 4 conduits between house and garage. Done it in 2 states. Last I knew, phone is not considered low voltage because the ringer uses higher voltage. Your mileage may vary.

Well, I stand corrected. I'll go turn in my license now...

[GDA]

Wow, I got a lot of reading up to do to digest and understand the suggested plan based on the advice given. At least I overestimated what I needed so my remodel budget continues to free up some $$$!

I need several days to do my own homework and I will be checking back with a much more specific plan to run by the group. I feel like I just went through "lets wire your house 101" :laugh:

Appreciate the help to the newb.

[Nestor]

Something to consider is whether heating/cooling is required. That'll add to your load.

Also, don't forget the beer fridge! :D

[alanaker]

I'm not sure if you're just bustin' them or what but there's no need for hostility, my internet associate!! We're all here to learn a bit and share right? I mean why else would we be here? I have no other agenda.

I just looked up in the NEC 2005 under 225.30 paragraph (D) and it specifically says it's o.k. to have extra circuits for the purpose of switching outside lighting from multiple locations between buildings. Let me know if I'm interpreting this wrongly, but be nice! On the phone thing, this could have just been a local thing, and I'm not even sure phone wire is covered by the NEC. (National Electric Code for those who would ask)

[MAC702]

...I just looked up in the NEC 2005 under 225.30 paragraph (D) and it specifically says it's o.k. to have extra circuits for the purpose of switching outside lighting from multiple locations between buildings...
You are correct. I had to clarify your original post since it did not specify OUTSIDE lighting. Also, there is no reason for this circuit to be in a separate conduit.

Two conduits, one for power, one for low-voltage.

We're glad to have you. :)

[alanaker]

MAC702 - We should probably finalize this with some sort of a unified position on the # of conduits required, so we're not leaving user GDA hanging. Did you see my p.m. yet? Post it if you want....

[MAC702]

Two are required, assuming he even wants low-voltage. Feel free to recommend as many as you like, based on your experiences and LOCAL REQUIREMENTS. It's obvious you have a qualified opinion that merits consideration.

[gimpyrobb]

I've worked in telcom for 8 yrs and have never heard voice considered High voltage. N.E.C. does have codes that apply and they are in the low voltage area. Local codes prolly trumped that in your case Alanaker. I can't tell you how many miles of voice and data I've pulled. At most the highest voltage I've heard of in voice is 48v. Sorry I hadn't checked in sooner. I feel that we have given very good info for GDA to start with. His contractor should fill him in on the rest. (Do you have a contractor?) Or did I step in IT.

[MoonRise]

To run things -into- the detached garage, he needs one conduit for the electrical wires running from the main circuit panel to the subpanel in the garage.

If he wants to have phone/cable/other wires running out to the detached garage, then all those 'low voltage' cables can go into the same separate conduit.

So barring any local code differences, he needs two conduits running from the house out to the detached garage, one for power and one for 'low voltage' stuff.

[NewbieRN]

What you do depends on if you want to be code complliant of not. From a practial standpoint you should not have a problem running a 100A feed into your garage from a 200A service panel. HOWEVER based on the load you describle if you were to derate and add it all up I think you will come up very short with a 200 A Service . Realistically you probably will not have a problem

[NewbieRN]

BTW .... The garage can have one and only one electical feed and it must have a disconnect before it goes into the branch panel. It must also have a grounding electrode rod