Setting up for 220 in my basement...I have a few questions*long*

[Steven Wilson]

...then I can do all the wiring to the sub panel, and then the electrician just comes into check everything and run one wire to connect the two?

I don't know what the regulations are where you live so I can't answer the question. In my area home owners may legally perform electrical work on residences that they currently or plan to occupy - not rental property, not commercial property, etc. Given that, I had an electrician wire in a subpanel for me because I was busy with some other things and wanted it done quickly. I then obtained the necessary permits and wired the branch circuits to my 220V tools. Once completed, and before final hookup I had the local electrical inspector come out and sign off on my work. Then I hooked up the machines. All of this is necessary for the work to be legal. Before undertaking this work I obtained a relevant copy of the NEC (box fill calculations, sizing, etc.), some books on residental wiring, and ran by the electrical inspector what my plan was (our electrical inspector has time set aside for answering question early in the morning). I'm fairly comfortable in performing most electrical work but maintain a healthy respect for what can happen if things go wrong. I will also follow code and follow the legal requirements for my area.

Now, my question is how comfortable do you feel in performing electrical work? Do you know what you are legally able to do in your area? Do you know what the governing code is in your area? Are there any local variations to the relevant national code? If you know the answers to those questions then enjoy the work, it's fairly easy. If not, then you have some homework to do.

Be safe and do it right.

[Tim Morton]

Now, my question is how comfortable do you feel in performing electrical work? Do you know what you are legally able to do in your area? Do you know what the governing code is in your area? Are there any local variations to the relevant national code? If you know the answers to those questions then enjoy the work, it's fairly easy. If not, then you have some homework to do.

I feel pretty Ok with doing all the wiring to the machines and setting up the sub panel, I will have help from a book, and friends. Where I DON"T feel comfortable is taking the main panel face off and playing around with the live wires. Hopefully i will be around when that part of the job is done so i can learn what to do and more importantly what NOT to touch

[Steven Wilson]

Where I DON"T feel comfortable is taking the main panel face off and playing around with the live wires.

Well you shouldn't ever have to play with "live" wires. And yes having the panel cover off has a significant pucker factor. When I dig into the main panel (for wiring) I have the main breaker off and my wife around with a 4x4 to knock me off of a wire if I get shocked. When I work on my sub panel I turn off the sub's breaker on the main. Then I check for stray voltages on the sub panel, that's before my fingers get in there to work with anything. When I was initially working on my sub panel I just pulled it's breaker from the main panel and felt pretty safe working on the sub. Just have a healthy respect for what you're doing. BTW, your friends may not be of any help because you're wiring branch circuits for use with motors. Depending on your local electrical authority and how you wire the circuits you may need to following the part of the NEC that apply's to motor circuits and not branch circuits. I suggest you start reading the NEC if you aren't familliar with it.

[Lewis Mills]

Ha! If I ever asked my wife to hang around with a 4X4 just in case, she'd knock me out with it before I even start and then call in an electrician!
Lewis

[Rob Russell]

Technically you are correct, Section 336-6(b) says it must be protected and it doesn't limit the length. One of the problems that sometimes comes into play, is how inspectors like to apply Section 310-15(a)(2) which applies to derating the ampacities of the circuit. The exception to this section says it doesn't apply to conduit that is 10ft long or 10% of the total circuit length, whichever is less. I've seen some inspectors that won't allow NM in conduits over 10 feet long because of this.

Inspectors can seem to be quite irrational at times and I have even had them completely ignore sections of the NEC just because they felt like it. The question then becomes, how long and hard do you want to fight with the inspector? The usual answer is it is best to do it his way and move on.

If the AHJ wants to get into derating of bundled NM, it's still not an issue until you have a lot of NM running through a single run of conduit.

From 334.80, "The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor." Using the 90 degree column and looking at Table 310.310.15(B)(2)(a) Adjustment Factors for More ThanThree Current-Carrying Conductors in a Raceway or Cable, you have to get more than 9 current carrying conductors bundled before derating becomes an issue for either #14 or #12. That means you can have (4) 14/2 or 12/2 NM through a conduit and - even with the 70% derating - you're still OK using 15 and 20 amp breakers respectively.

The issue here isn't whether or not the derating happens, it's whether or not the derating has any impact on the net ampacity of the circuit.

Steve,

I'm familiar with 430 (Motors, Motor-Circuits, and Controllers) because of my phase converter work. If Tim follows normal branch circuit wiring (#14=15 amps, #12=20 amps), uses plugs/receptacles to connect everything and doesn't have breaker trips when he's firing machines up - the normal branch circuit wiring methods will provide a more conservative setup than what's allowed under Article 430. In other words, Article 430 allows you to put more than a 15 amp breaker on #14 based on motor sizes and other factors. I really wouldn't go that route because it means those circuits would need to be dedicated to motor loads and that becomes restrictive in a home shop.

I'll agree that working in the main panel is pause for an extra safety check before pulling the panel cover off.

Rob
(Addy protocol - experienced homeowner electrician)

[Gary Sostrin]

When wiring up different circuits, you might want to put 2 separate 120v circuits in each box like I did in all around my garage and maybe some separate circuits for specific purposes (extra refrigerator, etc) and use different colors (black, white, silver, brown, etc) for the recepatcles. That way you have a visual indication of what circuit is being loaded. I have installed both main panel (200 amp) and garage subpanel (125 amp), and found that the advanced wiring book by black and decker (I think) shows how easy it is. I always work with power off, and when doing the main panel , I had the electric company disconnect power in the morning and reconnect in the afternoon.

Funny thing when I wired up the main panel (200 amp) using 00 (I think) cable to the pole , and labeled it (2 highs and a ground), a few of us watched the main power being wired from the pole to the house. The first electric company guy cut off all the cables and left. The second guy not seeing what the first guy did started wiring to the pole. Unfortuneately he tied the ground to one of the poles high side. No one was hurt, and excellent fireworks show. The second guy was cussing at me until I told him the other guy cut of the labels. Electrical accidents are nasty. I always work when power is dead. Electrical accidents could be fatal and burns do not heal.

[Wm Bauserman]

If the AHJ wants to get into derating of bundled NM, it's still not an issue until you have a lot of NM running through a single run of conduit.

From 334.80, "The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor." Using the 90 degree column and looking at Table 310.310.15(B)(2)(a) Adjustment Factors for More ThanThree Current-Carrying Conductors in a Raceway or Cable, you have to get more than 9 current carrying conductors bundled before derating becomes an issue for either #14 or #12. That means you can have (4) 14/2 or 12/2 NM through a conduit and - even with the 70% derating - you're still OK using 15 and 20 amp breakers respectively.

The issue here isn't whether or not the derating happens, it's whether or not the derating has any impact on the net ampacity of the circuit.

I'm not disagreeing with you at all. What I am saying is that it really isn't clear cut in the NEC and that if the inspector decides to pull a section out of nowhere and apply it, what do you do? It is much easier to just go with the flow in most cases than to fight it. If the inspector doesn't like NM in conduit behind drywall, what are you going to do?

I have inspectors that want to disallow things we do everyday in new remote switching stations even though the code specifically states it does apply to these facilities. But if we fight them and prove we are right, what do we gain other than a mad inspector?

[Michael Gabbay]

Tim -

Basically everyone has covered what I was going to say. I would strongly recommend the subpanel. When I finished by basement and built my shop I did that. It makes installing new circuits a snap. Also, I pulled all my cable and mounted all my boxes and had a friend (licensed electrician) do the hook up of the subpanel to main box. Working with live wires is somethiing definately left for the pros.

You may also want to cosider getting an electric permit from your county/city for the work. This will help protect you in case of an electrical fire with the insurance companies. I've seen insurance companies deny claims due to work that was never officially inspected. They'll do there best to not pay a claim.

my 2 cents...

Mike

[Steven Wilson]

I'm familiar with 430 (Motors, Motor-Circuits, and Controllers) because of my phase converter work. If Tim follows normal branch circuit wiring (#14=15 amps, #12=20 amps), uses plugs/receptacles to connect everything and doesn't have breaker trips when he's firing machines up - the normal branch circuit wiring methods will provide a more conservative setup than what's allowed under Article 430.

I agree Rob, He shouldn't have a problem but it's up to the inspector. My inspector basically said that as long as I wire my machines with pigtails and plug them in then my circuits just need to be branch circuits. However if I hardwire something like a DC or air compressor then he would treat them as motor-circuits. In any case you still need to be aware of this stuff before you start. The most usefull part of the NEC I found were the table associated with do box fill calculations. It doesn't take many wires running through a conduit before you have to increase the conduit size, increase a box size, find a cover plate with more volume, or derate the wiring.