Is it legal to wire a house with only 20 Amp circuits? (heating oil, stove)

[PacoMartin]

Originally Posted by Always Needmore

You say you have a main panel and a sub panel? I'd be interested to know if the total connected load of the main panel plus the total connected load of the sub panel falls under the total rated capacity of your main panel?

This is the system I inherited. Please stop insulting me, as I didn't design it.

The initial panel installed in the 1920s was 50A with twelve 15A circuits. Sometime, probably in the 1940s the home was upgraded to 100 Amp and the initial knife panel became a subpanel.

In the late 1970s the home was upgraded to 200A and the 100A panel became a subpanel. As more and more stuff was added to the home, two more 50A subpanels were added from the main box.

As circuits were added they seem to have been attached to any breaker box that was convenient.
Three 30A circuits were attached to the 200A main panel as well as a 100A subpanel and two 50A subpanel.
The 100A subpanel has three 30A circuits and a 50A circuit as well as the 50A subpanel with the knife switches.
One 50A subpanel with circuit breakers has a 50A circuit.
The other 50A subpanel with circuit breakers had two 30A circuits.

In addition

• 19 15A circuits with breakers are scattered throughout the system
• 20 20A circuits with breakers are scattered throughout the system
• 10 15A circuits with fuses and knife switches from the original box are still in use

Many of the wires are ancient and badly frayed.

It's very easy to say hire an electrician and rewire the entire house, but that would involve pulling down a dozen plaster walls and ceilings to get at the knob and tube wiring.

The one 50A subpanel with two 30A circuits began tripping off for some reason. I pulled the two 30A wires after it happened a dozen times and attached them elsewhere as they were for hot water and air conditioning.

I am also getting some outlets that seem to be failing for no apparent reason.

One 30A circuit led to a heater in the bathroom. The heater broke, but I wondered why a bathroom had such a large heater.
Another 30A circuit led to a cooktop which also broke, so I bought countertop ranges that hook to 15A or 20A circuits

Originally Posted by Always Needmore

So, is it accurate to say that you believe the wiring in place is "suspect", and that is your motivation for wanting to replace it all (start with a fresh slate)?

yes, that is accurate.

Originally Posted by Always Needmore

If the guy who installed the sub panel has the same respect for convention that you have, we might be getting warm here.

The work may have been done by half a dozen people over a period of 90+ years.

Originally Posted by Always Needmore

And that you are perhaps balking at the cost of higher amperage service components? Hoping that someone will tell you that it's okay to downgrade, just so you can save a few hundred bucks?

I'm a little worried that the homes 200A service is insufficient and it should actually be upgraded to 400A service. I believe we may be talking about tens of thousands of dollars here especially if multiple plaster ceilings are torn down to get at the knob and tube (mostly ceilings).

I thought it might be possible to replace some of the old appliances with new ones that require less amperge. There are 20A dryers now and even 20A ovens and cooktops. To the best of knowledge I am stuck with 30Amp sauna and hot water tanks.

The energy requirements of the home are very high. In the last 12 months the average electric bill has been for 2566 kWh, and in the last year the average heating oil usage was 1641 gallons for which we paid an average of $2.278/gallon. The heating oil price briefly peaked at $5.80 this year and electric rates have been going up as well.

[Sunbather]

4 amps is pretty tiny. Most of the bathroom heaters or fans and heaters I see install d these days are rated to 1.5 kW which is often going to be a 20A dedicated breaker. Since electric heat is straight resistance, there is no reason the load would drop unless you're comparing applesranges (different size heaters). For example, a 1.5 kW electric heater in 1950 uses the same amps as a 1.5 kW electric heater today (minus miniscule difference for fans/controls).

[Sunbather]

Originally Posted by PacoMartin

Once again I am not stupid. What does not make sense to me is why anyone would put such a huge heater/fan requiring 30A in a bathroom.

When I ask the question "Is it legal to wire a house with only 20 Amp circuits?" the assumption is that every device in the house only requires 20 Amps.

I understand that. And my response is simple- if you think every circuit in your house only requires 20 A, I think it speaks for itself: leave it to a professional.

Example: I believe NEC requires 30A breakers for any 220-240V electric dryer. Most modern ovens require 40-50A breakers. Most electric ranges require 30+ A breakers etc.

As far as the heater, I've already explained that.

[Always Needmore]

Originally Posted by PacoMartin

This is the system I inherited. Please stop insulting me, as I didn't design it.

.

I'm sincerely sorry if I have insulted you. That was not my intent. Just seems like you already have the answer you want in mind, and are looking for people to validate your strategy. So, I was perhaps a little bit in disbelief, and if that came across as an insult, I'm truly sorry.

From the sound of things, you have a mess on your hands Sometimes people with a little bit of knowledge and the best of intentions can be quite dangerous (the people who installed what you already got) Sounds like they knew enough to reach their immediate objective, but I doubt they engineered a balanced system.

Loose connections can cause phantom tripping in otherwise "sound" conditions.

[Northrick]

Some day someone else is going to own the house. They may change out appliances with the assumption that the circuits are to current code and can safely carry more than 20 amps (say for an electric dryer or range). That's why code on what is required where is what it is.

[ddeemo]

Originally Posted by PacoMartin

This is the system I inherited. Please stop insulting me, as I didn't design it.

The initial panel installed in the 1920s was 50A with twelve 15A circuits. Sometime, probably in the 1940s the home was upgraded to 100 Amp and the initial knife panel became a subpanel.

In the late 1970s the home was upgraded to 200A and the 100A panel became a subpanel. As more and more stuff was added to the home, two more 50A subpanels were added from the main box.

As circuits were added they seem to have been attached to any breaker box that was convenient.
Three 30A circuits were attached to the 200A main panel as well as a 100A subpanel and two 50A subpanel.
The 100A subpanel has three 30A circuits and a 50A circuit as well as the 50A subpanel with the knife switches.
One 50A subpanel with circuit breakers has a 50A circuit.
The other 50A subpanel with circuit breakers had two 30A circuits.

In addition

• 19 15A circuits with breakers are scattered throughout the system
• 20 20A circuits with breakers are scattered throughout the system
• 10 15A circuits with fuses and knife switches from the original box are still in use

Many of the wires are ancient and badly frayed.

It's very easy to say hire an electrician and rewire the entire house, but that would involve pulling down a dozen plaster walls and ceilings to get at the knob and tube wiring.

The one 50A subpanel with two 30A circuits began tripping off for some reason. I pulled the two 30A wires after it happened a dozen times and attached them elsewhere as they were for hot water and air conditioning.

I am also getting some outlets that seem to be failing for no apparent reason.

One 30A circuit led to a heater in the bathroom. The heater broke, but I wondered why a bathroom had such a large heater.
Another 30A circuit led to a cooktop which also broke, so I bought countertop ranges that hook to 15A or 20A circuits

I'm a little worried that the homes 200A service is insufficient and it should actually be upgraded to 400A service. I believe we may be talking about tens of thousands of dollars here especially if multiple plaster ceilings are torn down to get at the knob and tube (mostly ceilings).

I thought it might be possible to replace some of the old appliances with new ones that require less amperge. There are 20A dryers now and even 20A ovens and cooktops. To the best of knowledge I am stuck with 30Amp sauna and hot water tanks.

The energy requirements of the home are very high. In the last 12 months the average electric bill has been for 2566 kWh, and in the last year the average heating oil usage was 1641 gallons for which we paid an average of $2.278/gallon. The heating oil price briefly peaked at $5.80 this year and electric rates have been going up as well.

A circuit is supposed to be 20% larger than the load - this is so slight off spec items and startup draw doesn't overload circuits. So a 20 amp load is supposed to be on at least a 24 amp circuit - that is why the dryer is on a 30 amp - that is normal size. Anything larger than 20 amps is normally 230V so running on a xx/3 line nowadays - which is actually 4 wires (2 hot, 1 neutral and 1 ground) - the really old stuff was likely 2 wires, just the 2 hots with no neutral or ground - no longer considered safe so will have to do some rewiring at a minimum.

A heater you don't use - no need to rewire - a stove top should be rewired to at least 30 amps (40 amps would be better) so a standard top can be put back in if needed. Once you start working on knob and tube system, you are not allowed to reuse it in most places - you will most likely need to do at least some rewiring to put in grounds and neutral. Most do not pull out old knob and tube just stop using it by disconnecting each end and wiring around it - you can do most of it by fishing new wire through the walls or route under or over depending on access without damaging the plaster. Suggest not downgrading the wires - it is very little extra cost to wire right. You wont really save anything by downgrading 12/3 at 30 amps to 14/3 with 20 amps in 230v circuit.

200 Amp service is fine for 99.9% of houses- 400 amp is over kill for almost everybody and will likely require upgrading the connection to the street. Both of my houses pretty big and are on 200 amps with most of your loads and then some (I have pools and EV charging and 5 AC systems at one house) . Most even larger houses do not have that many 120v circuits - I have less than 30 circuits in both my houses. I am guessing that some of the stuff is being run through both old and new to prevent rewiring - a lot of stuff on sub panels are breakered more than once.

[PacoMartin]

Originally Posted by Always Needmore

From the sound of things, you have a mess on your hands Sometimes people with a little bit of knowledge and the best of intentions can be quite dangerous (the people who installed what you already got) Sounds like they knew enough to reach their immediate objective, but I doubt they engineered a balanced system.

I think that is pretty obvious.

I'll probably do what I have done for the last 10 years and just jury rig fixes when things break.I am just afraid the house is going to have to be sold for little more than the value of the land.

Originally Posted by ddeemo

200 Amp service is fine for 99.9% of houses- 400 amp is over kill for almost everybody and will likely require upgrading the connection to the street. Both of my houses pretty big and are on 200 amps with most of your loads and then some (I have pools and EV charging and 5 AC systems at one house) . Most even larger houses do not have that many 120v circuits - I have less than 30 circuits in both my houses. I am guessing that some of the stuff is being run through both old and new to prevent rewiring - a lot of stuff on sub panels are breakered more than once.

The house is 56' by 78' so it is very large. In comparison the yard of the house I grew up in was 45' by 110'.

This stupid heating system is steam radiators (which is rare in a residence). In the last seven years the average heating oil usage was 1641 gallons for which we paid an average of $2.278/gallon. The heating oil price briefly peaked at $5.80 this year. I have considered that it may make sense to put in some kind of an electrical heating system, which is why I thought that I may have to upgrade to 400 amp service.

In the last 12 months the average electric bill has been for 2566 kWh.

[ss20ts]

Have you checked with your town's building codes? This is work that needs a permit.

[ddeemo]

Originally Posted by PacoMartin

I think that is pretty obvious.

I'll probably do what I have done for the last 10 years and just jury rig fixes when things break.I am just afraid the house is going to have to be sold for little more than the value of the land.


The house is 56' by 78' so it is very large. In comparison the yard of the house I grew up in was 45' by 110'.

This stupid heating system is steam radiators (which is rare in a residence). In the last seven years the average heating oil usage was 1641 gallons for which we paid an average of $2.278/gallon. The heating oil price briefly peaked at $5.80 this year. I have considered that it may make sense to put in some kind of an electrical heating system, which is why I thought that I may have to upgrade to 400 amp service.

In the last 12 months the average electric bill has been for 2566 kWh.

Electrical heat is very expensive unless use heat pumps and that could involve a huge cost to retrofit unless can run ducts through attic and basements. Steam can be converted to hot water heat fairly easily - reusing radiators or replacing with baseboard system for much less than putting in new electric baseboard and cheaper to operate.

For 400 amp, you would have to have new power panel and new line run to supply - that alone will set you back at least $3000 and would likely trigger upgrading almost every wire in the house. 400 amps is 96Kw/hr - you would be able to draw your current usage in just over a day (27 hrs) - 200 amps is 48 Kw/hr - you are drawing about 3.6 kw/hr on average (2566kw/30 days/24hrs/day) - so you are drawing about 7.5% of max use on 200 amp so even 4x more power use would not likely be a strain unless most use was all concentrated in a couple of hours.

Just for reference, both of my houses are little larger than yours but they were built with 200 amp service. Stuff is getting more efficient also so demand can be less over time - the only large load I added was high speed EV charging in both - handled easily.

[wit-nit]

OP is your house insured and or are you responsible for any fire or other damage? If not self-responsible, and you have an insurance policy, that insurer eventually finds out any changes made are not permitted and up to code they will probably drop you and your coverage.