I need to run 100amp feeders from my main panel to a sub panel for my mobile home that’s about 235 Feet away.
I used the South Wire Voltage drop Calculator and it says Minimum Size wire I can use is 3/0 for AL. Am I able to use Polaris Taps to downsize the wire from 3/0 to 1/0 so it can fit into a 100 amp breaker at the main panel?
Edit: All wires discussed here are aluminum. Nevermind my previous typos.
This is you not using the calculator properly. Most novices make the same mistake.
First, DO NOT use an amp value of "breaker trip". Use the actual calculated load, e.g. if the load calculates out to 12240 VA or 51 amps, then use 51 amps. Regardless, you should never use more than 80% of breaker trip, because it's illegal to plan to load the panel that heavily. Consumer tier panels are only rated for 80% continuous load.
Second, 3% is only a wire salesman's suggestion. It's not in Code anywhere except in Canada, and there, they want 3% but at the above rule - actual load and never more than 80% of breaker trip.
So, when we calculate it on that basis - aluminum, 235', 240V, well over 3%, and 80 amps -- we get 1/0 aluminum at 3.26%. And that's just fine.
Or 1 AWG aluminum at 3.80% which is fine too, but since you're worried about it, go 1/0.
So, 1/0 aluminum is your best play. It fits the lugs natively, no fuss.
Remember feeders must be 4 wires.
Since you enlarged the beyond the minimum mandatory 1 AWG AL, you must enlarge ground in proportion (same number of AWG sizes) per 250.122(B). Minimum 100A feeder ground is 6 AWG, so you need
But yes, you can use Polaris to step down wires like that. It's just better avoided with brain power. Note that you wouldn't even need to use 1/0 for the pigtail since #1 would suffice.
Yes, you can do that. The issue of voltage drop due to wire size over long distances is proportional to the length of the smaller wire - i.e., 2 feet inside the panels is not a problem, and Polaris is the right type of connector to use at those sizes.
But a couple of notes:
The minimum for 100A subpanel feed is actually 1, not 1/0. 1/0 is good for up to 120A.
You may not really need 3/0 at 235 feet.
There are a few different factors involved. The biggest are: What is your actual usage? and How much at 120V vs. 240V?
100A is a typical subpanel size. Do you actually expect to use anywhere near 100A? In general you shouldn't be using much more than 80A, and 80A @ 240V @ 235' and 1 AWG = 3.80% drop, which is not that bad. On the other hand, if you run 50A @ 120V @ 235' and 1 AWG = 4.75% drop. And 80A @ 120V = 7.60% (which really is a problem).
So do a load calculation and figure out how much you are likely to really use at 120V and at 240V. Water heater, HVAC, oven are all typically (but not always) 240V loads and that makes quite a difference.
The good news is that even at 3/0 it won't cost a fortune with aluminum. But in addition to the wire cost, 3/0 is going to be harder to bend, feed, etc. than 1 or 1/0.
