Posted: 11/2/2015 10:42:21 AM EDT
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...or "This is Why We Have Code."
So I was buying a welder and needed any excuse to upgrade the electrical in my (detached) garage so decided it was time. When I bought the house, wiring the garage had clearly been an afterthought, since they ran UF from a junction in the basement that happened to be close, through the wall with just a bored hole (no physical protection), caulked it up, did a drop into the ground with some metallic (not wet location rated) conduit acting as a sleeve only, and then buried it to the garage, where it came up through the sill plate and into the light switch box. They ran two sets, one was for the outlets and lights, and one was only to serve for a three-way switch for the garage exterior lighting. The 20A breaker they had this attached to was too large for about half the wires on the circuit (lots of 14AWG), and they had: All the basement lights (including a built-out portion) All the basement sockets Half the kitchen sockets All the outdoor lighting All the garage lighting and sockets The kitchen ceiling light And topped it off with a doorbell transformer. They literally had stacked j-boxes four deep plus the transformer. I fixed most of that early on (I've owned the house ten years this month) and separated out circuits and checked wire ratings and such when I put in some ceiling fans, but left the garage stuff untouched (other than separating the three way switch wire and abandoning it in place). Now, I was going to put a 50A subpanel in the garage, but make sure that if I upgrade to 200A main service in the house I can run some new wires and upgrade the garage to 100A at that time. So, I got 1 1/4" Schedule 40 and associated pull elbows, #6 THWN conductors and a #8 THWN equipment ground, a 100A panel for the garage, and 6-3 w/ Ground for the interior runs. Grounding rods (BTW I borrowed a rotary hammer from work and holy shit was it easy - 25 seconds per rod) and all the other stuff I'd need to DO IT RIGHT. I went to trench for the conduit (A 10' run from the house to garage, 20" deep to meet the 18" minimum and some change) and the spade hit something that didn't feel like quite like a root... ...those mother fuckers had buried the UF cable three goddamned inches underground. I was planning on abandoning them in place since they should have been minimum 24" down. Luckily I had killed the breaker out there "just in case." I was able to pull the wire right out of the ground. Grrrrrr... Anyways, I'm getting everything buttoned up now, and if I do want to go to larger conductors in the future I can run copper out there in that 1 1/4" PVC and fit enough cable for 100A service, but I don't think I ever will. Technically I could check local code and see if I can jump from 50A to 60A since I'm actually rated at 55A and I know some places you can go up one size in protection, but whatever. I think 50A for an air compressor, and inverter TIG machine, and some other small hand tools and lights will be fine. But yeah... One day I will be dead and buried and another man will live in my house. I swear an oath that NO WORDS OF CURSING SHALL PASS HIS LIPS DUE TO WORK I HAVE DONE ON THIS HOUSE. I've done enough of that with this place for generations. |
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Haha I know that feeling very well! I bought my first house, built in 1964, this past May. It looked pretty good on the surface; however, once I started working on the electrical and items in the attic, it became apparent there were many things not done correctly.
I consider myself quite knowledgeable and handy with working on a house. It is also my goal to never leave anything that will have a future owner cursing or scratching his head. The previous owners of my house did many things so they were "good enough" but not quite right. |
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Yeah #8 THHN/THWN is good as an equipment ground with #6 of the same. We had a local company in at work doing a bunch of electrical so I was able to pick their brains, and that all lined up with the local electrical contractor supply house. Funny thing is I swear that 6-3 NM-B only has like a #10 ground.
Oh, and that square drive bit you swear never fell out of your torque wrench but must be on the floor over here somewhere? Yeah, it came off in the breaker when you were tightening it and is currently (no pun intended) inside your panel welding itself to the cover. 
Good news is the breaker works! LOL |
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Also, as a PSA - I know it is more work, but go ahead and run the THHN/THWN in conduit. It is a TON cheaper than NM-B. I paid $0.34/ft. for the single wire in #6 and $0.30/ft for the #8, and it is $2.22/ft. for the 6-3w/G NM-B cut-to-length or around $1.40/ft. in bulk (minimum 125ft roll). Also, you get to use the higher temp rating on the THHN/THWN so you can run a 60A off #6 no problem. For me I'm now limited to a 50A disconnect in the main panel feeding the sub because I didn't know about the 60* temp rating thing for the NM-B.
Oh, well. I sized the underground conduit and junction boxes so I can go back and run 100A service later on. Also, some asshole didn't use the antioxidant in my main panel and the neutral on the service entrance looks like it is about to flake apart. Shit. |
| Oh, yeah... that, too. They had phone wires sticking through the basement wall and run underground in rusty conduit a few inches down, too, so most of the wires had been cut into over the years. I don't know about code violations or anything there, but what a shoddy job. |
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It is now - I made damned sure it was cut back and taped off at both ends. Quoted:
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I discovered that the conduit to my garage not only contained building wire, but phone wire as well. May be fine. It is now - I made damned sure it was cut back and taped off at both ends. There is plenty of twisted pair line with an external jacket rated for use in cable trays and conduit with 120 V right beside it. |
out of me. What a douchebag.
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So the subpanel is up and working - now I just have to get the outlet run for the welder and tie in the existing wiring to the panel. While I'm at it I need to pull every cover from every junction box and receptacle in the garage to make sure they have the right gauge wire in there and didn't do any weird splicing or anything (since they do have #12 and #14 in the box at the light switch and it *looks* like they were using #12 to feed the outlets, #14 to feed the lights, and #12 for the shared neutral). I'm separating the lights and garage door (15A circuit) from the receptacles (120V 20A circuit) and replacing the receptacles with 20A rated units. Gotta make sure I've got #12 in the conduit for the receptacles. Also I think I need to fish more wire through regardless because right now it looks like they have one shared neutral in the whole system (which was maybe fine when they had one feeder going to the garage from the house but I can't have shared neutral for different circuits!).
At least I've got a single outlet to run the garage door opener and a light while I work so I can stop running the work light from my house! Or, should I just put the garage door on its own 15A? It isn't hardwired so I could also just bundle it with the 20A receptacle circuit. Maybe I'll feel saucy and run two 20A receptacle circuits - one for each half of the garage... |
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There is plenty of twisted pair line with an external jacket rated for use in cable trays and conduit with 120 V right beside it. Quoted:
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I discovered that the conduit to my garage not only contained building wire, but phone wire as well. May be fine. It is now - I made damned sure it was cut back and taped off at both ends. There is plenty of twisted pair line with an external jacket rated for use in cable trays and conduit with 120 V right beside it. Allowed for low voltage and 120v control circuits, yes. But I don't believe it's allowed for high current 120v. And besides which, this was NOT shielded Cat 5 with a 600V jacket. This was 20 year old 4 conductor telephone wire. A previous owner had run this stuff to EVERY room in the house, and had landline phones everywhere, including bathrooms. Given the quality of that installation, and what he did to the rest of the electrical systems, NFW am I trusting that as anything but a pull string. |
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Allowed for low voltage and 120v control circuits, yes. But I don't believe it's allowed for high current 120v. And besides which, this was NOT shielded Cat 5 with a 600V jacket. This was 20 year old 4 conductor telephone wire. A previous owner had run this stuff to EVERY room in the house, and had landline phones everywhere, including bathrooms. Given the quality of that installation, and what he did to the rest of the electrical systems, NFW am I trusting that as anything but a pull string. Quoted:
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I discovered that the conduit to my garage not only contained building wire, but phone wire as well. May be fine. It is now - I made damned sure it was cut back and taped off at both ends. There is plenty of twisted pair line with an external jacket rated for use in cable trays and conduit with 120 V right beside it. Allowed for low voltage and 120v control circuits, yes. But I don't believe it's allowed for high current 120v. And besides which, this was NOT shielded Cat 5 with a 600V jacket. This was 20 year old 4 conductor telephone wire. A previous owner had run this stuff to EVERY room in the house, and had landline phones everywhere, including bathrooms. Given the quality of that installation, and what he did to the rest of the electrical systems, NFW am I trusting that as anything but a pull string. It was likely fine. Even the 20 year old stuff had enough jacket thickness for being used adjacent to 120 V. The individual wire insulation is over 3,000 V |
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It was likely fine. Even the 20 year old stuff had enough jacket thickness for being used adjacent to 120 V. The individual wire insulation is over 3,000 V the current version of The Book you have states that when run in the same raceway the low voltage wiring must have a marked insulation voltage rating greater than the AC circuit wiring is carrying, correct? ar-jedi |
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the current version of The Book you have states that when run in the same raceway the low voltage wiring must have a marked insulation voltage rating greater than the AC circuit wiring is carrying, correct? ar-jedi Quoted:
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It was likely fine. Even the 20 year old stuff had enough jacket thickness for being used adjacent to 120 V. The individual wire insulation is over 3,000 V the current version of The Book you have states that when run in the same raceway the low voltage wiring must have a marked insulation voltage rating greater than the AC circuit wiring is carrying, correct? ar-jedi IIRC that sounds correct. The code grandfathers everything that complied with any previous version. The exact wording starts to matter since "marked" on the spool may meet the letter of the requirement. |
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IIRC that sounds correct. The code grandfathers everything that complied with any previous version. The exact wording starts to matter since "marked" on the spool may meet the letter of the requirement. Quoted:
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It was likely fine. Even the 20 year old stuff had enough jacket thickness for being used adjacent to 120 V. The individual wire insulation is over 3,000 V the current version of The Book you have states that when run in the same raceway the low voltage wiring must have a marked insulation voltage rating greater than the AC circuit wiring is carrying, correct? ar-jedi IIRC that sounds correct. The code grandfathers everything that complied with any previous version. The exact wording starts to matter since "marked" on the spool may meet the letter of the requirement. ahhh, got it. i'm not in the trade -- just learning along the way as i stumble through a myriad of projects. thanks. ar-jedi |