Anandtech electricians need some advice

[master_shake_]

i am adding new receptacles to my garage. currently there is one.

i am running a 12-3 wire from my panel in the basement out to the garage (attached).

i need to know if i have to use a ground wire when using EMT and metal conduit inside my garage if i ground the 12-3 to a metal box and use all steel runs from the main box.

i live in ontario if code is an issue.

 

[Red Squirrel]

Some places don't require a separate ground while others do. I'm not sure about here in Ontario, I think it's still required. Since you're using 12/3 it should already have a ground conductor anyway, so I'd just use it. Make sure the metal boxes are also grounded.

Same with BX I always still use the ground that's inside even though the BX itself would technically be sufficient.

 

[bommy261]

I would use the ground wire regardless. There is a tapped hole for a grounding screw in many metal boxes nowadays, it doesn't take up much time at all to tie the metal box to ground.

 

[NutBucket]

Just curious but why 12-3? If it were me I'd run something more substantial and put a sub in the garage. Just makes life easier in the future.

 

[NetWareHead]

If you are running 12-3, there is a ground conductor already in that cable. Im assuming you are running the 12-3 out to each outlet...

 

[master_shake_]

i talked to my cousin he's an electrician he said i have to bond my grounds to the box but if i am running straight conduit with no pvc or expansion joints i don't need to ground every box with a continuous ground.

also since i am using stranded (thhn) wire i have to use forked crimp connectors did not know that.

also i am using a 12-3 wire so i can split them at the wall and do half the garage on one circuit and the other half on the second.

i thought about using a sub panel but i don't think the need would arise for more capacity.

also i learned that i can use bx in my cold air return to get out in to the garage.

thanks everyone for your input,

 

[NutBucket]

More capacity...maybe adding 220 at some future date for a welder or EV charger? Just things to consider.

 

[stormkroe]

Emt can be used as the ground. Also, you can pigtail solid core wire to your stranded to avoid spade connectors (I hate them).

 

[stormkroe]

He'll have 220 if he runs a 12/3.

More capacity...maybe adding 220 at some future date for a welder or EV charger? Just things to consider.

 

[NutBucket]

But he said he's using it to run two 120 circuits....and it's only 20 amps which isn't enough for most stuff that wants 220.

 

[master_shake_]

i have zero interest in welding in my garage.

if needed i can weld at work.

i use wood tools and i don't think i'll ever have a cabinet saw (room constraints).

 

[NL5]

also since i am using stranded (thhn) wire i have to use forked crimp connectors did not know that.

If you are referring to the receptacles, just get the kind made for stranded wire.

 

[master_shake_]

If you are referring to the receptacles, just get the kind made for stranded wire.

apparently receptacles that are ul listed accept both solid and stranded wire.

you don't need terminals.

oh well, got 100 for 10 bucks.

 

[Red Squirrel]

First I hear of stranded wire being used for permanent electrical. Are you sure that wire is rated for in wall use? I hope it's not lamp cord or extension cord wire or something. You did say 12/3 so at least it's 12 gauge... it should technically be ok.

Don't back stab the outlets though, while that is normally kinda frowned upon anyway, I definitely would not do it with stranded wire.

 

[master_shake_]

First I hear of stranded wire being used for permanent electrical. Are you sure that wire is rated for in wall use? I hope it's not lamp cord or extension cord wire or something. You did say 12/3 so at least it's 12 gauge... it should technically be ok.

Don't back stab the outlets though, while that is normally kinda frowned upon anyway, I definitely would not do it with stranded wire.

all the outlets are mounted on the outside of the drywall.

and i am using EMT to connect them.

i am not gutting a garage to put in electrical.

 

[Red Squirrel]

all the outlets are mounted on the outside of the drywall.

and i am using EMT to connect them.

i am not gutting a garage to put in electrical.

No that's fine, but you mentioned stranded wire, so I'm just wondering what kind of wire you ran through the EMT. Normally building wiring is solid.

 

[master_shake_]

No that's fine, but you mentioned stranded wire, so I'm just wondering what kind of wire you ran through the EMT. Normally building wiring is solid.

thhn wire

 

[NetWareHead]

I kinda like to do things above code for added safeguards. Most of the time, code = minimum. Pull the extra ground wire for better sleep at night.

You can use EMT as the ground as it provides good continuity, but all of your connectors must be tight and secure. If you have a locknut work itself loose (from vibration for example), your ground path is broken.

 

[NL5]

Normally building wiring is solid.

Stranded is way more common in everything except resi. Solid is cheaper, but it sucks to work with it.

 

[natto fire]

No that's fine, but you mentioned stranded wire, so I'm just wondering what kind of wire you ran through the EMT. Normally building wiring is solid.

I have been an electrician for over 5 years, and we pretty much never pull solid wire in raceways, including EMT. I know Teck cable is very popular up north and we have our own hack equivalent in MC cable here. I also prefer putting devices on solid wire.

That said, any "electrician" who pulls solid wire in any decent EMT run is scraping by. Sure, in residential, the runs are much shorter, and solid can be pulled in short runs that have few bends. However, most electrians just default to stranded.

So, just to let you know, there is stranded building wire out there that is not lamp cord.

 

[Red Squirrel]

Oh right I guess the thicker stuff like Telcoflex #2 and stuff would be considered standed. I always still considered that solid, as the "strands" are very thick but guess it's still stranded given it's not just one big strand inside. Just never seen any "building" rated #12 or similar residential sizes stranded before so that's why I was surprised.

 

[NutBucket]

Pulling solid wire definitely sucks.

 

[master_shake_]

i went ahead and pulled the extra ground instead of bonding all my receptacles.

 

[Micrornd]

If I understand correctly, you are running a "12/3" romex with a separate ground wire, not "12/3 w/ground" romex?

That is suitable for only a single 220v/120v appliance circuit, such as a dryer or stove.
But that is not code legal or suitable for two separate 120v circuits, as the single neutral wire can be forced to carry 40 amps ( if both circuits are fully utilized) and creates a fire safety and fire hazard.

You really need to pull "2-12/2 w/ground" cables or single "12/2/2 w/ground" cable (sometimes labeled "12/4 w/ground") or if you stay with the "12/3" and an additional ground wire, you need an additional neutral wire for the second circuit.

 

[master_shake_]

it's called a multi-wire branch circuit.

First, both breakers for the MWBC should be tied together. This is reflected in Virginia Residential code E3701.5.1 which states “Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors a the point where the branch circuit originates.

An ungrounded conductor is the hot conductor. So in simpler terms most homeowners should understand, the breakers need to be tied together so the power will be shut off to both hot wires in the MWBC.

This is done to prevent an electrician from being shocked. If an electrician doesn’t disconnect both hot wires in an MWBC, or does not kow he is working on an MWBC, the circuit he is working on will be energized from the other hot wire in the MWBC.

Second, the MWBC breakers must originate from opposite bus bars. Each residential panel has two bus bars powered from L1 and L2.

When wired improperly an MWBC can cause the neutral to become overloaded. When both circuits originate from the same line (same bus bar) the current running through the neutral will be the sum of both circuits. When both circuits originate from opposite phases (different bus bar) the current running through the neutral will be difference of both circuits.

Let’s consider 15 amp circuits in a scenario where both circuits draw 10 amps at the same time. If both circuits are on different phases, the current through the neutral will be 0 (the difference between both circuits.) If they are on the same phase, the current through the neutral will be 20 amps (the sum of both circuits).

20 amps is too high for 15 amp circuits on a 14-3 cable. The neutral will be overloaded. This can cause the insulation to deteriorate and can cause arc fault fires.

as long as the breakers are on different 120 circuits then there is no chance for an overload.

kinda like a split receptacle in your kitchen.