ELECTRICAN GURUS:

[machmeter62]

We do 100amp subfeed runs all the time at work. If you check with your local electrical supply house,not a box store they can supply you with everything you need . A 300ft run with the right size triplex or cable in conduit is not that unusual. If you anticipate a large draw at once you could consider a step up /step down transformer from square D. We have run 100 amp services 1800 ft with such a setup.

Macdabs

How big is the transformer, and how close to the main house would be it's proper placement? What is the average cost of this unit? Would it "hum...noise," and create interference with other electronics? I think 100 AMPS is the maximum the site needs, and only household power is required.

 

[SPIKER]

as you know the cost of copper has tripled in last year or so and as such so has transformers, which are mostly copper and steel. 100 amp transformers would be pretty expensive, and you will need 2 of them one at each end one to STEP UP the other to STEP DOWN the voltage. while there will be a savings in the long run of wire & conduit the extra cost is also a good bit. lots to consider, if only a few hundred feet not worth the extra problems the 1800 feet (I think he said) is a different critter... there are other costs such as fusing and disconnects to think about for the transformers as well on each end... the placement and the likes. most times the HUM is due to LOOSE items inside the case and or as they get old insulation/potting materials get loose and vibrate with the 60 htz magnetic field that is inside the unit... this is often the reason for the high bay lights HUMMING excessively loud is the small glue laminated high voltage transformer inside them that rattles and or the magnetics effecting metal parts inside the case... I've found a few that were still working that the laminated steel trans stack came apart and had warn through the alum case but was still functioning though I'm sure the light output was effected somewhat...

mark M

 

[MACDABS]

The type of transformers can be found on Square D s website, we use different sizes depending on the length of the run and draw. Service disconnects are req. on both ends , and would be recommended if you are doing any subfeed with a underground run from a primary service. If you can run primary with a second meter , without a lot of cost that is the way to go . If not a step up step down or a buck boost transformer depending on the size starts a t a few hundred. Plus as mentioned you should have a fuseable service disconnect at each end . Physical size varies depending on the size of the transformer and if a outdoor enclosure is req. ,. Some of the transformers our size of a sixpack and on up. I think the last one I did with the 1800 ft run , cable transformers , two service disconnects, small 1oo amp breaker panel all NEMA enclosures was in the $7500.00 range, with $4500.00 of that was the direct burial triplex. The local power company would have been 45k plus engineering cost and right a way fees. (over farm to the site location) If you have a co-op for your electric I would go primary, they are great to deal with ,and look for a 30 year pay back on material from power consumption. I hope this helps , many electricians that do plant and factory work should be able to tell you what setup is safe and best for you.

Macdabs

 

[Illini22]

Direct bury wire is repaired all the time, you just need to find the fault in it. it also has another major advantage compared to conduit, and that is if the service does get hit or dug into your damage is going to be where the digging was at and all you need is some splices, shrink tubes and a couple of feet of wire. If it were in pipe you maybe buying new panels at both ends and whatever else is conected to the wires. if you did go direct bury I would fill that trench up with 4" drain pipe and poly for conduits for the future. As far as finding the fault on secondaries, a dynatel is what I've always used (24 yrs.) and it always works of course theirs many others. A 2/0 nuetral with 4/0 phases would carry 200 amps all day long and its pretty common wire size in the midwest.

 

[machmeter62]

Direct bury wire is repaired all the time, you just need to find the fault in it. it also has another major advantage compared to conduit, and that is if the service does get hit or dug into your damage is going to be where the digging was at and all you need is some splices, shrink tubes and a couple of feet of wire. If it were in pipe you maybe buying new panels at both ends and whatever else is conected to the wires. if you did go direct bury I would fill that trench up with 4" drain pipe and poly for conduits for the future. As far as finding the fault on secondaries, a dynatel is what I've always used (24 yrs.) and it always works of course theirs many others. A 2/0 nuetral with 4/0 phases would carry 200 amps all day long and its pretty common wire size in the midwest.

We are talking about some huge wire now; I wouldn't loose any energy due to heat loss in the 4/0 wire??!! I assume this would be aluminum wire, especially the 4/0....about a 1/2 in diameter? This is getting interesting, and the choices are re-educating me! Copper for this project would require a construction loan!

 

[quicksandfarmer]

We are talking about some huge wire now; I wouldn't loose any energy due to heat loss in the 4/0 wire??!! I assume this would be aluminum wire, especially the 4/0....about a 1/2 in diameter? This is getting interesting, and the choices are re-educating me! Copper for this project would require a construction loan!

You may want to rethink whether you really need 100 amps. That would be the easiest way to trim costs. Of course, you might be kicking yourself down the road if you underestimate.

 

[machmeter62]

I haven't checked the county requirements, but I would guess 100 AMPS would be about the minimum with clothes washer, dish washer, clothes dryer, electric hot water heater, micro-wave, and A/C too, would challenge anything less when operated together The A/C is needed for only a couple of months per year. I would also rather have too much, then the problems of not enough amperage. Retired people enjoy space heaters also, that draw the voltage down.

 

[Illini22]

mach, yes I was talking al. wire. Usually menards has it for under 3.00$ a foot, as well as many electrical supply houses. Also when you make up the ends in say a milbank or square d meter trough make sure you put frost loops in the wire. What are they? they are bends in the wiresfrom the ground up the meter trough (inside) to where you terminate. When the ground heaves or after the foundation is backfilled and settles it gives you enough slack that it won't rip your meter trough off the house or break the meter block in raceway. Another helpful tip, if you see any utility lineman on the road stop by and (be nice) ask their opinion. They do that work all the time and they may even have some extra splices, lugs shrink tubes etc. etc........wire. You can also bury some yellow safty tape after backfilling halfway, it may save someone down the road. Also always call for locares even if you know where everything is and you called last month for some other reason. Call again, many times I've been on jobs where they didn't call locates in. Their reason was," I called last spring (you pick the date) and they said it was over there not where I was digging". Well the locater that located last spring was wrong and now you just hit(you pick gas, water, phone, electric, fiber) something that will be expensive because you didn't call in a locate. Now if you havn't called yet, go call.

 

[kmdigital]

What is the anticipated electrical load? Are you going to use a gas or electric water heater? Gas or electric dryer? Gas or electric range? The answers to these questions make a big difference IMO. Without any major electrical appliances, a 100 amp service will rarely see continuous loads in excess of 15-20 amps or so, and usually less. In these cases, the voltage drops over a wire rated for 100 amps will be very negligable.

Even a central AC doesn't take all the much, depending on size. If I remember correctly, the nominal rating is 8 amps per ton (or HP) for a 240 volt compressor. The primary power hogs are the various forms of electrical resistance heating, and if you are using these, then oversizing the wire to reduce voltage drops is a good idea. Personally, I would use aluminum wire for the underground, either direct burial or in conduit due to the much lower cost. This is what most utility companies use, and there is nothing wrong with it in the larger heavier sizes used for services.

 

[kenmac]

I used 00 alum. wire ( same stuff power co. uses here) in 2'' conduit to serve my garage off the main from my house. have had no problems . Wire has been under ground for 10 yrs. 2 hot 1 nuteral 1 ground