electrial cable and propane line

[dd20399]

i built a new workshop 300ft behind house...used a trencher and installed moble home underground service,put a 100 amp breaker at house and installed a breaker box at building..i used 20 ft of pvc conduit at house meter box..been slow in getting ditch filled in..when i got around to covering it up at house i seen a copper pipe at bottom of ditch and the cable is laying on it..copper line is propane line,which runs across the ditch,i shoveled the ditch in this area so the line wasn't damaged.....question, is how much distance should be between the propane line and cables,i have a piece of 3/4 thick rubber mat material..i wished i had put in another section of pvc but i didn't and the rest of ditch is filled in and wired into panels...i want to make it right and not worry about it

[HayZee518]

sub panel

if your triplex isn't physically touching the propane line you should be ok. the electrolysis problem comes into play when there is physical contact. the copper should take on a brown patina anyway being buried which will "kind of" insulate it from the inground minerals.
make sure you isolate your neutral bus bar at the remote panel and install an aux ground bar connected to a driven ground rod. use #6 stranded bonded to this aux ground bar and the driven ground bar.

[dd20399]

the cable has 4 parts 2 hots,1 neutral,1 grd..these are alu and each insulated..i grd sub panel but used a #6 solid copper wire to grd rod,is that a problem...it is possible that it is touching in the ditch so i am shoveling that section up this morning ang put distance between them,thanks for the info

[HayZee518]

sub panel

my only question to you is: are the neutrals and aux ground separated?
there should be NO bonding screw or jumper between the chassis and neutral ground strip. If you have it bonded, remove the jumper or screw. the driven ground [wire] goes to the aux strip. if you have none go buy a grounding bar and put it somewhere in the bottom section of the panel. your #6 goes here.

[dd20399]

i don't like what i am seeing,first i went to the new sub panel,the panel, eaton,did have a jumper connecting the 2 buss bars and grding case itself,i have now removed that jumper..i have only the big neut cable soley, no chassis grd on that one,the other buss bar i have the smaller green cable, on with a strap to panel and grd copper to rod on that buss.....my problem is looking at house,square d,it has clearly marked neut cable to a buss bar and neut's going to it ,including the one i put from building...and it has the #6 grd cooper wire going to rod.. the other side buss bar just has the straded alu cable attached to it,trhere's where i put building grd.......to me this isn't right at house..at house i have a 200 amp panel inside the garage..on the outside at meter there is a panel that only have the a/c and heat breakers,that's where i am adding a breaker for building...do i need to swap the grd and neut at house or does the house grd cable need to be moved to the other buss or none of the above

[HayZee518]

sub panel

any panelbox that is fed off a breaker in the MAIN panel is called a sub panel.
the neutral bus bar in the MAIN panel is the ONLY place the bar is BONDED to chassis ground either through a jumper or screw through the bus bar hole into the metal panel.
all white wires go to the neutral bar. bare equipment grounds go to the neutral bar.
the main panel [200 amp] should have a #4 stranded bare copper wire bonded to and around a water meter line in the dwelling. An auxillary driven ground rod consisting of two rods spaced six feet apart and driven the entire eight feet into the ground is required [check with your local inspector] a ground loop of #4 goes from the panel to the ground rods and then back to the panel neutral.
sub panels are the only place an aux ground is used with an isolated neutral bar.

[dd20399]

you are correct on all i have except the water and i have well water and pex lines,i thank you very much,i don't know way the sub panels need non grded neut's but it sounds like i was very lucky you caught it in my orginal post or it would have stayed wrong...my main panel has a large flat strip so it don't may any differance which one i used for grd and other neut at the main...i can see at least #4 coming in from house sub and going to buss on main...thanks again

[HayZee518]

SE panel & sub

I drew a diagram which should help show you what I'm talking about pertaining to the neutrals and equip grounds

[dd20399]

what is the 4 wire going to do that a 3 wire cannot? at the sub panel...thanks for the info,i am learning

[HayZee518]

sub panel

you ran the four wire! I would have run a three wire, myself and used the driven ground as an equipment ground. the reason for the separate ground is to prevent objectional currents from energizing the panelbox which would happen if the neutral was bonded to the chassis metal. ideally the current path is from the hot, through the load and back to the neutral, which connects to the center leg of the transformer at the pole. the aux ground is there for fault currents, leakage paths if a motor winding grounds out.

[dd20399]

in nc it's the law for moble homes and it seems to be a big deal for new construction for 220 appliances,the burial cable is popular at supply house's....i was just curious why, which you have expained,thanks again for your help so maybe i can stay out of trouble for an hour or two

[HayZee518]

why four wire?

Back in 1996 the NFPA came out with a directive that all dryers, ranges, devices that made use of cord and plug terminations of the 240 volt variety use a four wire pigtail and receptacle.
Used to be ONLY mobile homes that needed this type of configuration, now everything requires it.
I ran into a four wire service entrance only once in Massachusetts and this was on an underground entrance for a mobile home [side by side] I might add. To top it off the entrance was made to the meter location using a 100 amp weatherproof receptacle and cord and plug. CROUSE-HINDS used to be the only company that made this plug and receptacle, now they're all doing it. ARKTITE is another.
Something else you should be aware of is, any new construction no matter where it is [dwelling, garage, out building] you must make use of something called an AFCI or Arc Fault Cicuit Interrupter.
This is not the same as a GFCI or Ground Fault Circuit Interrupter. An AFCI is much more sensitive.
At first it was to be used on circuits that terminate in a bedroom. That's because people were hanging pictures in the room and, not knowing where the studs were, hammered in nails or screws and penetrated the romex cable outer sheath and MAY HAVE shorted out the hot-neutral or hot-ground or both and the breaker did not trip. What you had was a high resistance short that took time to heat up and eventually cause a fire. So, now everythi
ng gets to use an AFCI. And they're not cheap!