Electric Question

I'm not quite understanding my available electric service. Any information from more knowledgeable people would be greatly appreciated.

My question, or lack of understanding comes from the relation of 240v and 120v.

In my instance I live in an older home equipped with a fuse box. The main feed to the fuse box is connected to a 50amp breaker on the pole just after the meter. There is also a 100amp breaker in this box that is not utilized.

I am assuming this means I have 50 amp 240v service to my fuse box. I understand that watts divided by voltage equals amps. So items pull roughly twice the amperage at 120v. So does that mean that my 240v 50 amp box will support 100 amps of 120v circuits?

Currently the fuse box contains 3 15 amp circuits for my lights and outlets, 1 15 amp circuit for my gas furnace, 1 20amp circuit for my gas stove, 1 20 amp circuit for my refrigerator, and 1 20amp circuit for a washer that is not utilized. There is also a second box with two 30amp breakers that is connected to the fuse box which appears to be going to a non used four wire dryer connection.

All in total, minus the furnace blower my max draw would be roughly 33.41amps at 120v. What I am trying to ultimately figure out is how and where to add or relocate a circuit to power one or two small a/c units. An additional circuit for my ballast would be great as well, but that circuit is only pulling 8amp now so it isn't critical.

I would really hire a electrician to give you a quote, because unless we have blueprint for your house we don't know how hard it is to fish the new wires around. Electrical quotes from licensed electricians are free usually. Are you gonna install a Mr Slim split AC? Don't wanna burn your house down

_MrBelvedere_ said:

I would really hire a electrician to give you a quote, because unless we have blueprint for your house we don't know how hard it is to fish the new wires around. Electrical quotes from licensed electricians are free usually. Are you gonna install a Mr Slim split AC? Don't wanna burn your house down

Click to expand...

No, I'm not going to burn the house down, if there is any doubt I would call someone. I still like to have a firm grasp of what I need before hand. I find it lowers the odds of getting screwed by less than honest service people.

A mini split is one option. Cost and power are my deterrents at the moment. I could do a single head for the grow room, but then I have to explain to the wife why my plants have ac and the bedroom doesn't. The larger multi room units cost quote a bit more and require a dedicated 240v circuit. In the end two window units might be better, it would certainly be cheaper initially.

We have a swamp cooler, but I doubt its ability to cool the grow room come mid summer.

sure makes sense A window unit is way easier to deal with then all the expense of having the splits installed...

For the grow room, you should find what circuit it is on. Then see if that circuit is powering your bedroom, bathroom, etc. If that circuit is also powering your bedroom and bathroom, then you may def need a new circuit for your grow room. Otherwise when you turn on a vacuum cleaner on that circuit it could trip the breaker and shut down your grow lights... A AC unit is a must in summer, the swamp cooler will not pull the humidity out of the room. The cool thing about the window AC is that it is also a dehumidifier so your RH will be perfect!

I would probably do the mini split install myself, not much to it other than electrical work. The bulk of cost difference is the 1k plus for a mini split versus $150 each for window units.

I did check my circuits, and mapped out which breaker controls every light, appliance, or outlet in my home. The circuit for the grow room only goes to that room and is pulling 8 amps total. Still safe, but adding anything more than a 5k btu ac will put it over 15amps.

There is no humidity to remove here. Im in southern Colorado where today's rh is a whopping 16%. Adding moisture wont hurt, but I don't think it will benefit enough to cool my grow room properly.

Ok cool, sounds good. Happy growing!

I would use the unused 30 amp dryer circuit and get a mini split,