Yea, I realize you can't have an electrician come in while the op. is in progress... With proper planning, all the wiring should be done before hand. Even then, upgrades are sometimes necessary. So this is why we do it ourselves.
I have no problem with standard wiring procedures being done by homeowners. It's really quite easy once you get the basics down. It's when you start dealing with motor controls, ballasts et. all that a "qualified" person should be doing the work. Again, just make sure you know what your doing beforehand.
Terminology: (sorry for the basics)
Neutral = grounded conductor
Hot = ungrounded conductor
Ground = grounding conductor
conductors = individual wire
cable = An entire assembly of multiple conductors jacketed with an outer sheath.
AL = aluminum
CU = copper
OCPD = Over Current Protection Device (a.k.a circuit breaker)
Conductor ampacities (Table 310.16
I've slightly modified 14 and 12 gauge to fit residential applications so this table isn't verbatim from the NEC. Look at the 6 gauge CU ampacity for romex. Says 55 amp. The NEC allows you to bump up to 60A since there is no 55A OCPD (good luck finding one anyway). Same with 4/0 CU (pronouced four aught). That's good for 200A. But look at #3 CU. Don't use that for 100A. Only round by 5 if there is no breaker that matches the ampacity. You would need to use #2 CU or 1/0 AL for 100A feeder.
The 75 degree column is for using individual conductors only
(the ones listed). They must be run in conduit. You can also only have 3 current carrying conductors in a raceway (conduit). If you have more, you need to start de-rating the wire. I won't go into that. The grounded (neutral) conductor counts as a current carrying conductor but the grounding conductor does not.
Remember to do your Voltage Drop calculations before running feeders for sub-panels or branch circuits coming out of panels. Don't exceed 3% for feeders and 2% for the branch circuits. A total of 5% from your main panel to the point-of-use.
Pretty sure I mentioned this before, but always use copper wire. The only time you should be using aluminum is for large
feeder cables that power a sub-panel. When you do use AL, you must
use anti-oxidant compound on your connections. It's a dark grey goop that comes in a tube. If you don't, over time, the wire will oxidize and start to look like your battery terminals on a car. White crusty crap every where. This shoots resistance thru the roof and AL already has a higher resistance than CU. Any time you have a high resistance, you get heat, which isn't good. Make sure you use the correct columns in the chart above for CU and AL ampacities. When applying anti-oxidant compound, don't get crazy with it. Just enough to evenly coat the entire exposed part of the AL conductor.
All Romex or NM-B cable is rated for 60 Celsius. The individual conductors are rated at 90 degrees but the cable assembly is rated at 60. This is your typical cable you buy for your house. Shown is a roll of 12/2 with ground.
MC (metal clad) cable is also applicable for 60 Celsius. It has a green sheathed grounding
AC cable is also rated at 60 Celsius: Notice the grounding conductor is AL and not sheathed. It is in contact with the outer metal jacket. Most places will only sell Type MC cable (which is what you should use instead of AC). Also notice the anti-short bushings (a.k.a redheads). Use them for both Type MC and AC cable. They protect the conductor insulation from being damaged on the cut rough edges of the metal jacket.
SEU cable is also rated at 60 Celsius. These should only be used to feed your main panel coming from your meter. Thus, you will never use it because you shouldn't be inside your meter anyway.:wink: Not a very good pic. Notice it has two sheathed ungrounded conductors, then around those, you will find individual strands of AL wire. These are to be twisted together to form an uninsulated grounded (neutral) conductor. There is no grounding
conductor in this cable.
Type SER is also rated at 60 Celsius. This is what you would use to feed a panelboard (a.k.a sub panel). This is copper but will typically come in AL, just like SEU cable. It has 2 ungrounded conductors. One should be all black, the other all black with a red stripe. There will also be a sheathed grounded (neutral) conductor. It will typically be all black with a white stripe. Then you'll have an uninsulated grounding conductor.
When feeding sub-panels, you need to use SER cable. All grounded (neutrals) and grounding (grounds) conductors need to be isolated in a sub-panel. If you guys look at your main panel, you'll probably see both grounds and neutrals terminated to the same buss bar. Don't do this in a sub-panel.
Here is a MLO panelboard (M
nly sub-panel) fed with, what looks to be 6 or 8 gauge romex. If it's #6 CU romex, then you have to use no larger than a 60A double pole breaker in your main panel
. If it's #8 CU romex, then no larger than a 40A double pole breaker in your main panel.
conductors (red and black) are connected to the top 2 main lugs which in turn feed the hot buss bars.
conductor (white) is connected to the large lug on the neutral buss bar. The neutral buss will be isolated from the frame of the panel. Notice this panelboard has 2 neutral buss, the other one is hiding to the left.
conductor (no sheathing) is connected to the ground buss. This will be directly fastened to the panel frame. Some panelboards don't come with a dedicated ground buss. You must
purchase and install it separately if not. I also don't like the location of that ground buss. Too close to the hot and neutral buss. I would have put it down below.
Here's a close up of the isolated neutral buss:
Notice the bonding bar with the green screw. Remove this entirely. Some panelboards will come with a thin bonding strap, others will come with a long green grounding screw. It's to bond the neutral bus to the frame of the panel if
you are using the panelboard as a main panel. In that case, you would loosen the screw, rotate the bar to the right and put it under one of the terminals on the neutral buss, then tighten down both screws. Don't
do this on a sub-panel.
Make sure you purchase the correct circuit breaker for the panel you are using. There is "Square-D type QO", "Siemens type QP", "Cuttler-Hammer type BR" and so on, and so on.... It's paramount you use the correct manufacturers breaker.
Here is a single pole 120v circuit breaker. Used to feed branch circuit 120v loads.
Here is a double pole 240v circuit breaker. Used to feed 240v branch circuits and
feeder cables to sub panels:
Here is a tandem breaker. It fits in a single slot but is designed to feed 2 - 120v loads. Do not
use this to feed a 240v load. For 240v loads, the breaker needs to pull from both hot legs that feed the panel (red and black feeder conductors). This breaker only pulls from one of the hot legs supplying the panel. Both hot conductors for 240v also need to have a common trip, meaning the handles need to be joined. Here they are not. You would also want to read the spec sheet for your panelboard and see if it is rated for tandem breakers. I don't really condone the use of them, but, if they are allowed to be used in the panel, it's a good way to free up space for an extra circuit (if your panel is full). Just don't get crazy with them.
Back to the panelboard.... Make up your connections in the panelboard before
you tie in the feeder cable at the main panel. That's common sense. Once that is done, go back to your main panel and tie in the feeder you just ran to the panelboard. You want to use a double pole 240v circuit breaker. This means you need 2 free spaces in your main panel to power your sub panel.
When ever you make connections anywhere
, always do it in this order. Connect your ground first. Then connect your neutral, then connect your hot last. When taking a connection apart, reverse the order. Hot, neutral, ground.
So, to connect the feeder cable in your main panel, attach your grounding
wire first. This will more than likely get terminated to your neutral buss in the main panel as will the neutral wire of our feeder like so:
If your neutrals and grounds are separated in your main panel, this likely means you have an outside disconnect right below the meter. That means your main panel is actually a sub-panel!!! If that's the case, then you would tie the ground wire for your new sub-panel feed onto the isolated ground buss in your main panel.
Hope I didn't loose anyone there.But... If all your neutrals and grounds are terminated to the same buss bar in your main panel, both the neutral and ground of your sub-panel feed get terminated to your main panels neutral buss bar as the pic above shows.
When terminating wires to lugs, you really need to torque them down good. Some times the panel/equipment will list the torque specifications, other times it won't. Just tighten them down good. Typically, with a #14 ground wire, I'll wind up crushing them to about 2/3rds of their original diameter. If you've tightened them down to the point where you've reduced the diameter in half, then your tightening too much.
Then take your left over 2 hot conductors for the feeder cable, and attach each one to the double pole circuit breaker. There will be 2 screws on the breaker. One for each wire.
Once the screws have been torqued down on the breaker, make sure the breaker is in the "off" position and then snap it onto the hot buss bars of your main panel. If this makes you nervous, then throw your main breaker to kill the entire panel before you do so. In fact, I recommend that anyone kill the main breaker before they even take the cover off. Don't take chances. You can buy battery powered ball caps at Lowes or Home Depot.... :wink: That or the head lamps.
Breakers will attach in various ways to the hot buss of your panel. Study the breaker and around the hot buss on your panel. Usually, the "screw side" of the breaker will have little hooks and you can see a place for them on your panel. Put those in first and then push down on the breaker to make a connection with the hot buss.
Turn your main breaker back on but leave the double pole breaker that feeds your new sub-panel "off". Don't power that up until you've ran your branch circuits out of the sub-panel.
That burned me out but I can post later with pics on how to install branch circuits....