| Author | Message | ||
| Russell Beam (Rcbeam)
Registered Member Username: Rcbeam Post Number: 5 Registered: 11-2009 Posted From: 72.250.169.58  Rating: N/A |
I have discovered that the P/O has run most of the house wiring with BX cable. Also the breaker box does not have a ground bus but only 1 ground wire that is bonded to the box. I'm not sure yet if anything upstairs is grounded or not. I suspect maybe he has the outlets grounded to the chassis at each point instead of running hot, neutral, and ground for each circuit back to the breaker box. Sounds to me like I need to take all of this out and redo it to run grounds and also change out the breaker box to include a ground bus. Any experts care to give me some input? | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1132 Registered: 1-2003 Posted From: 64.150.184.38  Rating: N/A |
Type AC cable (the technical name for what is commonly referred to as "BX") uses the metal sheath as the safety ground for the circuit. For this reason it is important that proper Type AC fittings and metal boxes be used at each end of every run. Nowadays it is preferred to use type MC which has a separate safety ground conductor, but when your coach was done it is possible that AC was an accepted wiring method. So long as all the fittings are tight and the boxes are all metal, your wiring is probably safe. For any new runs, I would use MC, NM, or THHN in ENT with proper ground wires. If all the circuits in the coach are type AC, that would explain the lack of a ground bus in the box, as the box itself would be the grounding method for the jackets. I presume the box does have a proper neutral bus that is isolated from the metal box itself, is that correct? -Sean http://OurOdyssey.BlogSpot.com (Message edited by Sean on August 01, 2010) | ||
| Russell Beam (Rcbeam)
Registered Member Username: Rcbeam Post Number: 7 Registered: 11-2009 Posted From: 74.131.50.239 Rating: N/A |
Sean: Thx for bringing me up to speed on the terminology. He has run some in AC cable and somewhere along the way switched to romex. The two receptacles I have looked at upstairs are surface mount type with no fitting for AC cable. What I have running downstairs to the panel is THHN wires for hot and neutral with only 1 #10 or #12 green wire screwed to the panel box. I don't know where it connects to the rest of the house wiring as yet. The more I see the more leery I get of it all. Sean, I for one really appreciate what you do here to help many of us. This board is a better place because of members like you. Thx again for you feedback. | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1133 Registered: 1-2003 Posted From: 72.171.0.148 Rating: N/A |
Russell, Thanks for the kind words. If there is AC cable that does not properly end at a metal box, then, yes, you will need to replace either the cable, or the box and fittings. Type NM cable, often referred to by Southwire's trademark Romex®, will have a separate ground conductor, usually bare copper, between the two current-carrying conductors, and this ground conductor should be terminated on a ground buss bar in the main panel. Since you said there is no such bar, I'm wondering what they did with the loose ground wires from any NM cables they installed. This, too, will need to be fixed. If the grounds were clipped off short, then you'll either need to replace the cable or add an intermediate junction box or raceway in which to splice the cable to a section with the ground intact. The THHN wires feeding the panel are fine, so long as they are run inside of rated conduit. You mentioned the size of the ground but not the others. The ground wire is permitted to be one trade size smaller than the current-carrying conductors. So a #12 ground would be fine for a #10 circuit, which is good for 30 amps. A 50-amp panel would require #6 conductors, so the ground would need to be at least #8. If the wires are not in conduit, it might be possible to fix this without pulling them all the way out. You'll need to get the ends at least out of the panel or box at each end, and if the stars align, you might then be able to slip flexible ENT (Electrical Nonmetallic Tubing, often called "smurf tube" because a popular brand comes in a bright blue color) over the wires and push it all the way to the other end. Sounds like you might have some work ahead of you, but it's probably not necessary to rip all of it out. A lot most likely can be fixed with a little work at the ends. -Sean http://OurOdyssey.BlogSpot.com | ||
| Russell Beam (Rcbeam)
Registered Member Username: Rcbeam Post Number: 11 Registered: 11-2009 Posted From: 74.131.50.239 Rating: N/A |
Finally found my grounds. P/O ran H/N/G on all runs to a large box under the dinnette... then from there ran the H/N bundles downstairs to the breaker panel but tied all of the grounds to a bus bar in this box upstairs and then ran one larger ground wire by itself downstairs. Some of the AC cable that I've seen so far has plastic inserts and some does not. Looks like I have some fixing to do before I go any further. |