Wiring Garage Questions

[machsnell]

Hello i have read a few posts trying to find the answer and have found additional info but still have a few questions for the electrical gurus.

1 - if i have 3 garage door openers can they be wired on the same circuit? or individual?

2 - how many outlets per 15 or 20 amp run are allowed?

3 - can i have multiple outlets on a single 30 or 50 amp 240 run?

4 - i will have a lift and should i dedicate a circuit for that?

5 - if i am unsure of my 240 equipment amperage requirements should i wire it for 50 amp and can you set up a multiple type 240 plug on the in a junction box or should i do 20 30 and 50 amp styles? totally lost on this one.

Thanks in advance

 

[TonkaJoe]

While I am unable to help answer all of your questions as I don't own a lift or have any of the large voltage wired up for my needs I can answer a couple..

#1. If you have a 3 car garage with 3 garage door openers, here is what you could expect:
3 openers x 4 Amps = 12 Amps for the opener PLUS 3 lights x 1.67 Amps = 5 Amps for the lights. Keep in mind these numbers are at the high end of the average.

When planning an electrical circuit, the circuit load should be 80% of maximum. 80% of 15 Amps = 12 Amps and 80% of 20 Amps = 16 Amps. So, 3 garage door openers with 200 Watts of light running simultaneously would draw up to 17 Amps. While this slightly exceeds the 16 Amp maximum for a 20 Amp circuit, it is VERY unlikely you will ever have all 3 openers running at the same time.
My recommendation is a dedicated 20 Amp circuit for 3 garage door openers. For 1 or 2 openers, a 15 Amp circuit.

#2 The NEC doesn't limit the number of receptacles you can place on a 20-amp circuit, but you'll overload the breaker if you run appliances that draw more current than the breaker can handle. The NEC does specify that a circuit breaker shouldn't handle more than 80% of the load for which it is rated unless the breaker is labelled otherwise. As a rule of thumb in counting devices on a circuit you count each outlet (light or receptacle) as 1.5 amps. Now remember you only count 80% of the rating which means a 15 amp breaker should not exceed a 12 amp load, a 20 amp breaker would be 16 amps. Based on that, you should not have more than 8 devices on a 15 amp circuit, and no more than 12 on a 20 amp circuit.

Note: As per NEC 2008,
Ground-fault circuit-interruption for personnel
shall be provided as required in 210.8(A) through (C). The
ground-fault circuit-interrupter shall be installed in a
readily accessible location.
Informational Note: See 215.9 for ground-fault circuit interrupter
protection for personnel on feeders.
(A) Dwelling Units. All 125-volt, single-phase, 15- and 20-
ampere receptacles installed in the locations specified in
210.8(A)(1) through ( shall have ground-fault circuit interrupter
protection for personnel.
(1) Bathrooms
(2) Garages, and also accessory buildings that have a floor
located at or below grade level not intended as habitable
rooms and limited to storage areas, work areas,
and areas of similar use
(3) Outdoors
Exception to (3): Receptacles that are not readily accessible
and are supplied by a branch circuit dedicated to
electric snow-melting, de-icing, or pipeline and vessel heating
equipment shall be permitted to be installed in accordance
with 426.28 or 427.22, as applicable.
(4) Crawl spaces — at or below grade level
(5) Unfinished basements — for purposes of this section,
unfinished basements are defined as portions or areas of
the basement not intended as habitable rooms and limited
to storage areas, work areas, and the like.
-- I know it doesn't state anything about a garage door circuit as resetting it would need to be accessible, in this case maybe use a GFCI breaker for the openers?.

Hope this is a good start!, anyone please feel free to add to or correct any of my information. Good luck!

 

[rockwithjason]

tonkajoe has a pretty good grip on it. i will add my comments in red

Hello i have read a few posts trying to find the answer and have found additional info but still have a few questions for the electrical gurus.

1 - if i have 3 garage door openers can they be wired on the same circuit? or individual?

i would have to look this up to be sure but since these are intermittent loads i would see no problem with having one circuit serve them

2 - how many outlets per 15 or 20 amp run are allowed?

see tonkajoe's answer

3 - can i have multiple outlets on a single 30 or 50 amp 240 run?

yes but most consider this a bad practice

4 - i will have a lift and should i dedicate a circuit for that?

yes

5 - if i am unsure of my 240 equipment amperage requirements should i wire it for 50 amp and can you set up a multiple type 240 plug on the in a junction box or should i do 20 30 and 50 amp styles? totally lost on this one.

if you are unsure then run 1" conduit and be ready for future use. wiring for 50a will not terminate into smaller devices so it's better just to have a pathway to get what you want where you want it.
Thanks in advance

 

[75gmck25]

The other option for #5 is to wire in a 60 amp garage subpanel with 6/3 wire and a 50 amp breaker in the main panel, and then run the wiring for your 240 circuits off the subpanel once you decide what you need for a 240 volt receptacles. If you get a subpanel with 6 breaker positions you could have three 240 volt circuits with different receptacles types, and then just manage the load by turning on/using one circuit at a time. This requires some caution and manual load management, since the sum of all the breakers (80 amps) exceeds the capacity of the 50 amp breaker in the main panel, but I don't think its unsafe.

You could also use a 100 amp subpanel, but cost for the main feed wire goes up quite a bit if you want to actually use the full 100 amp rating. You can reduce the cost by using aluminum MHF wire, but some folks don't want to use aluminum. It may also be harder to find a 90 or 100 amp breaker for your main panel to feed the subpanel.

Bruce

 

[pattenp]

Hello i have read a few posts trying to find the answer and have found additional info but still have a few questions for the electrical gurus.

1 - if i have 3 garage door openers can they be wired on the same circuit? or individual?

2 - how many outlets per 15 or 20 amp run are allowed?

3 - can i have multiple outlets on a single 30 or 50 amp 240 run?

4 - i will have a lift and should i dedicate a circuit for that?

5 - if i am unsure of my 240 equipment amperage requirements should i wire it for 50 amp and can you set up a multiple type 240 plug on the in a junction box or should i do 20 30 and 50 amp styles? totally lost on this one.

Thanks in advance

#3 All depends on building use, where you live and what codes are in place and are enforced. International Residential Building Code does not allow multiple 240V outlets over 20 amps on a single circuit.

 

[machsnell]

Thank you all for the answers quickly.

i would do the 60 amp sub but i am already planning on running the garage off a 100 amp sub panel from the main 200 amp panel from the house.

I dont think it will be overloaded with lights and 110 stuff. i have pellet stove there and no other big juice ***** except the compressor which i will power off the main house panel and have outside.

also i will only use the 240 one at a time.

That is a bummer that only one 240 outlet per circuit. my 240 stuff is like 40 to 50 feet from my sub panel and that wire is pricey.

Thanks for help.

 

[happy2rv]

You haven't given us any information about what type of garage this is going into or how you will use it, so see my comments in red below for "generic" information. How you will use the space will change the electrical requirements.

Hello i have read a few posts trying to find the answer and have found additional info but still have a few questions for the electrical gurus.

1 - if i have 3 garage door openers can they be wired on the same circuit? or individual?

The 1/2 HP liftmaster I looked up was rated at 6A. So Three of them would be a maximum of 18A. Which if considered continuous load would exceed the maximum allowable load for a 20A circuit. I think they would be considered noncontinuous loads and therefore be ok, but I would verify that with an electrician and/or inspector.

2 - how many outlets per 15 or 20 amp run are allowed?

A better question is how will you use the outlets and what makes sense for you? You CAN put 8 outlets on one breaker but when you plug a saw into one outlet and a shop vacuum into another you will trip the breaker. Not to mention if you wanted to plug a space heater into a third outlet. Personally I would have a minimum of 1 circuit per wall and multiple dedicated circuits in any designated shop area. If this is a daily driver garage used only for parking and you just want "convenience" outlets say to move a vacuum cleaner from one outlet to another 1 circuit may be fine, but will you ever change your mind? It's far easier to put it in now than later after everything is sealed up.

3 - can i have multiple outlets on a single 30 or 50 amp 240 run?

Why would you? Typically 30 or 50 amp outlets are dedicated to large heavy equipment that you aren't going to move around and require a dedicated circuit. Even if you have multiple items that you think you won't use at the same time, in the end you probably will. I'm with rockwithjason on this one. If you don't know what you might need right now run conduit and pull what you do need later. Multiple circuits can share the same conduit, assuming it's big enough, so you only have to run one conduit and branch off to each location. The conduit will be MUCH cheaper than the wire, especially if you end up putting the wrong thing in and have to redo it later.

4 - i will have a lift and should i dedicate a circuit for that?

Yes. Even if it's 110V it will pretty much equal the max load for a circuit. Could you get by having it on the circuit with something else? Maybe, but why take the chance? If it's 220V it will definitely need a dedicated circuit. Have you decided on a lift? Two post, four post, or scissor? What are it's electrical requirements. If you haven't decided, did you plan when pouring concrete to support a two post lift? Here again, if you're not pretty certain of the requirements you could run a conduit for future use.

5 - if i am unsure of my 240 equipment amperage requirements should i wire it for 50 amp and can you set up a multiple type 240 plug on the in a junction box or should i do 20 30 and 50 amp styles? totally lost on this one.

See answer to #3 above.



Thanks in advance

 

[machsnell]

Thanks for replies.

Agreed i havent said what it is used for. Mainly race car and fab work and misc work when i have time. no daily drivers at all. Welder, plasma, bandsaw but i also have a joiner and planer that are 220.

It is 1700 sf and an odd layout of a shallow v. it has 160 plus lf of wall space minus the three doors.

I keep most items mobile so they always arent in one spot depending what i am working on. I was just hoping to daisy chain the 220 like the 110 circuit but no big deal.

I may just put in the conduit as suggested and try and nail down better. i could also install different 220 plugs and have heavy extension cords for them like i did for my welder. i guess i need to stop thinking about them like 110 outlets where the more the merrier.


Lastly, is it true that outlets need to be minimum of 2' from the ground? or should i check my local for the answer because they are all different?

Thanks again for all the input.

 

[happy2rv]

Standard disclaimer: I'm not an electrician by trade...

I don't think there is an NEC code requirement for minimum height. I have seen references to 18" minimum in a garage, but never found a code reference. In interior spaces, its not uncommon to see floor outlets. It is uncommon in new construction, but somewhat common in older construction to see them installed in baseboards.

Having said that, the reason most often given for keeping them above 18" in the garage is to avoid igniting flammable vapors like gasoline vapors. Local enforcement may have different requirements. Some jurisdictions enforce ADA requirements in addition to electrical code requirements and there are ADA requirements for height of outlets.

 

[TonkaJoe]

^ This above is a good rule of thumb for the height.. the reasoning behind that height or extra in a garage/ shop environment is due to moisture or actual water getting into the outlet from a vehicle or anything else in the area... which is another reason why I mentioned the NEC code of having your outlets GFCI in the shop area.

 

[pattenp]

Standard disclaimer: I'm not an electrician by trade...

I don't think there is an NEC code requirement for minimum height. I have seen references to 18" minimum in a garage, but never found a code reference. In interior spaces, its not uncommon to see floor outlets. It is uncommon in new construction, but somewhat common in older construction to see them installed in baseboards.

Having said that, the reason most often given for keeping them above 18" in the garage is to avoid igniting flammable vapors like gasoline vapors. Local enforcement may have different requirements. Some jurisdictions enforce ADA requirements in addition to electrical code requirements and there are ADA requirements for height of outlets.

I believe you thinking of the 18" from NEC Article 511.3 for area classification of commercial garage space that deals with wiring placement.

 

[drelldrell]

I have a follow on question. If LED lights are used, does that significantly reduce amp load to circuits?

 

[rockwithjason]

it all depends on the fixtures used but generally you get more light for less power with led