A Realistic Look at Tiny-Home Utility Hookups

The 30-amp versus 50-amp question is where most tiny-home utility planning goes wrong, and it goes wrong because the numbers look close together. Fifty is not quite double thirty. It sounds like a modest upgrade. It is not: a 50-amp hookup gives you roughly three and a third times the power of a 30-amp one, and the reason has nothing to do with the twenty amps in between.

Thirty amps is not 240 volts, and that is the whole story

A 30-amp hookup is a single 120-volt hot leg. Look at the receptacle spec: Hubbell’s sheet for the standard TT-30R lists it as 30 A, 125 V, three-wire grounding. One hot, one neutral, one ground. A 50-amp hookup is a NEMA 14-50R running split-phase at 120/240 V: two hot legs, and Milbank’s pedestal datasheet shows exactly this, with the TT-30R fed by a single-pole 120 V breaker and the 14-50R by a two-pole 120/240 V breaker in the same box.

Multiply it out. Thirty amps at 120 volts is 3,600 watts. Fifty amps at 240 volts is 12,000 watts. Those are also, not coincidentally, the figures the National Electrical Code uses when sizing an RV park’s service: NEC 551.73(A) requires calculating on the basis of not less than 12,000 volt-amperes per 50-amp site and 3,600 per 30-amp site (JADE Learning’s summary of the code change notes the 50-amp figure was raised from 9,600 in the 2017 edition).

The adapter will not save you

The “dogbone” adapter is the most common misunderstanding on this subject, and the manufacturer settles it without ambiguity. Camco’s 30-amp-male-to-50-amp-female adapter and its 50-amp-male-to-30-amp-female adapter carry the identical rating: 125 V, 3,750 W. Both of them. Plugging a 50-amp rig into a 30-amp post gives you 30 amps of 120-volt power in a 50-amp-shaped connector. The adapter changes the plug, not the pedestal.

What 3,600 watts actually runs

Here is where it stops being abstract. A single 13,500 BTU air conditioner, per Airxcel’s data sheet for the Coleman-Mach, draws 14.6 to 15.3 amps running at 115 V, and pulls a locked-rotor inrush several times that at startup.

That one appliance is half your 30-amp service. Add a 12-amp electric water heater element and you are at 27.3 of 30 amps, about 91 percent, with roughly 325 watts left. A microwave is 1,000 watts and up. The breaker trips, and it trips at the pedestal in the rain, not in your kitchen.

This is the practical shape of a 30-amp life: you sequence. Water heater on gas, or water heater on electric but not while the A/C is running. It is entirely livable. It is just a thing you have to know before you sign a lot lease, rather than discover on the first hot afternoon.

The hose is a health decision, not a hardware one

Do not use a garden hose for drinking water. This is not fussiness. The Ecology Center tested 32 hoses in 2016 and found that 7 of 24 PVC hoses contained between 100 and 68,000 ppm lead, and water sampled from three of them came back at 13, 19 and 20 parts per billion. The EPA action level is 15. Water that sat in a garden hose exceeded the federal threshold in two of three samples.

A potable hose is certified to NSF/ANSI/CAN 61 for drinking water contact, with NSF/ANSI/CAN 372 covering lead-free content. You can check any specific product against NSF’s own certified components database rather than trusting the packaging. A common one, Camco’s TastePURE, is rated to 150 psi. The hose is not your weak point.

Your plumbing is the weak point

Municipal supply can arrive well above what small-home plumbing tolerates, which is why the IRC caps it. Section P2903.3.1 limits static pressure in a dwelling to 80 psi and requires an approved pressure-reducing valve above that. A cheap inline regulator like the Camco 40055 is preset to 40-50 psi, has garden hose threads on both ends, and costs about twenty dollars. If you want to dial the pressure yourself, Watts’ LF263A series is adjustable with a 300 psi maximum working pressure.

One detail worth insisting on, and it connects to the hose above: buy the lead-free version. Watts’ older 263A is discontinued precisely in favour of the LF (“Lead Free”) line, and the Camco unit specifies lead-free brass. A regulator sits in the same drinking water path the NSF 372 mark is about. There is no sense certifying the hose and then screwing a leaded brass fitting onto the end of it.

Twenty dollars against a burst line inside a wall. Fit it at the spigot, not at the house, so the hose is protected too.

On tank sizing: the EPA puts average household use at 82 gallons per person per day. A 60-gallon freshwater tank is therefore under one person-day at municipal habits. That number is not a reason to panic, it is a reason to understand that tank living is a different set of habits, not the same habits with a smaller reservoir.

Propane: the tank math is easy, the cold is not

The arithmetic is simple. A 20 lb cylinder holds 4.7 gallons per Worthington’s spec sheet, and propane carries about 91,452 BTU per gallon per the EIA. That is roughly 430,000 BTU in a tank. A Suburban NT-16SEQ furnace burns 16,000 BTU/hr, so about 27 hours of burner-on time. A furnace cycling at 30 percent duty gets you several days, not 27 hours.

Now the part almost nobody plans for. A tank does not deliver propane, it delivers vapour, and vaporization depends on liquid surface area and temperature. RegO’s LP-Gas Serviceman’s Manual publishes the table: a 100 lb cylinder that delivers 300,000 BTU/hr at 70 degrees F delivers only 113,000 BTU/hr at 0 degrees F. And it falls again as the tank empties, because there is less wetted wall to boil off. A tank that ran your furnace fine in October can fail to keep up in January while still showing propane in it.

Below that, physics stops cooperating entirely. RegO’s vapour pressure table shows propane at 28 psig at 0 degrees F, 13.5 at -20 degrees F, and 3.6 at -40 degrees F. A regulator needs roughly 10 psig inlet to hold the 11 inches water column your appliances expect. Somewhere around -20 degrees F you simply run out of driving pressure. In genuinely cold country the answer is a bigger tank, not a fuller one.

When it goes wrong: if your furnace short-cycles or the flame drops on the coldest night, that is usually not a broken furnace. It is vaporization. Warm the tank if you safely can, switch to a larger cylinder, or run two tanks in parallel to double the wetted area.

Sewer is a legal question wearing a plumbing costume

The hose part is easy. The law is not, and it is where people get genuinely stuck, because greywater rules do not vary by degree between states. They vary by concept.

• Arizona permits residential greywater reuse under 400 gallons a day with no application, no fee and no inspection under R18-9-711, provided you meet the listed conditions.
• Massachusetts does not let greywater touch a landscape freely at all. Under Title 5, 310 CMR 15.262 it goes through a septic tank and a soil absorption system.
• Florida inverts the premise: greywater there is plumbed to flush toilets. In the Florida Building Code’s plumbing chapter, the subsurface landscape irrigation section is marked “Reserved,” meaning it is simply not a thing.

And the definition catches people out. California’s Plumbing Code Chapter 16 excludes the kitchen sink from greywater. The sink you would most expect to qualify is the one that does not, because of food solids and grease.

There is no national answer here. Call your county before you buy a single fitting.

Which code applies to you at all

This is the honest ambiguity underneath everything above, and it deserves saying plainly rather than smoothing over.

If your tiny house sits on a foundation, IRC Appendix Q may apply where adopted. It defines a tiny house as 400 square feet or less excluding lofts, and relaxes real things: ceilings to 6 ft 8 in, loft guards below the usual 36 inches, and ladders as legitimate loft access, which the base IRC does not permit for habitable space. It does not waive emergency escape openings.

If it is on wheels and built to NFPA 1192 or ANSI A119.5, it is an RV, exempt from HUD standards under 24 CFR 3282.15 on the condition that it is “designed only for recreational use and not as a primary residence.” Read that sentence twice if you intend to live in it full time. That is the fault line the whole classification rests on, and it is unsettled enough that the Tiny Home Industry Association is still working the standards question.

Your classification determines which utility rules bind you. Settle it first. It is not paperwork you do at the end; it is the question every other answer on this page depends on.

The order to do this in

Find out what your jurisdiction thinks you are. Then find out what the site offers, 30 or 50 amps, full hookup or partial. Then size the propane to your actual winter, not your average one. Buy the pressure regulator and the potable hose on day one, because together they cost about forty dollars and prevent the two failures that are expensive and the one that is a health problem.

Everything else you can adjust later.