Well I dont envy you running those heaters Cynthia, thats 3Kw per hour and I dont know what you paying in BC but i would not run those babies when i dont need them if i were you.
I see the blank spots in the panel and my question is, is this going to be your shop now on a permanent basis. That is are we getting geared to camp there for a good while. Cause if so I would rather not take up all those slots but rather only take one up for a sub panel which can be placed in a convenient spot to suite you and the altered layout of the room from before. This would allow expansion to more breakers where you can still have your 220V and get to have more dedicated or at least less receptacles per circuit.
I think its important that you fundamentally understand why things are tripping now.
So even though i do not wish to confuse you.
Keep this rough formula in mind.
P = V times I
Now P equals the power in watts
V equals the supply voltage which could be 120v or 220v
I equals the current that is flowing measured in amps.
So lets for a moment consider your heaters.
1 heater is 1500w at the rated voltage of 120v
What that means in current terms is that when its on full blast it will have around P/V 1500 divide by 120 equals 12.5 amps running through it.
Now figure, the normal receptacle is rated for a max of 15 amps. They will from a safety aspect carry more but that is dangerous they were not designed to do that. So when you have two heaters on one receptacle you are exceeding the current rating for that receptacle.
Ok you say but Rob i put it into two different receptacles and it blew the breaker.
Here is why. In our codes we are allowed more than one receptacle. Its actually a crazy number that you can go up to and i wont quote it here. The premise is though that you aint gonna load them all up at once and if you were to be doing that, then it would most likely be very small indiviual loads such as say Cell phone chargers or computers or a printer etc. Most of these devices consume power in the low hundreds of watts not 1000's as you heaters or machinery will do.
So to protect us and again in my little dig to the safety and economic expedience here in NA we rely on the use of a 15 amp circuit breaker at the end of the receptacle line. But this means that the sum of all the currents flowing in all the receptacles on that circuit should be preferably under 15amps. When you have your two heaters on and connected to receptacles or extension cords that essentially all run off the same circuit breaker you can see that just the two heaters alone would trip the 15amp breaker. Now its likely that if that was a garage previously that they might have put a 20Amp breaker in the panel for the receptacles to cater for something like a welder which will have a surge current. Regardless you are still exceeding the load and that is totally unsafe.
Its important to your safety (and this is why i campaign that people get a bit of this experience ) that you understand this regardless of the aspect of whether you do your electrical or even need an electrian or are going to make any changes to your electrical. You should understand these things simply as a homeowner and excuse me for saying this but more as woman because of things like curling tongs and hairdriers.
So when you look at what you need in a shop my suggestion is less receptacles on one circuit and more individual circuits where you can run machines without them sharing the load on the line with some other device you might want to run such as a shop vac.
I think while i am on it i should let you understand how this overloading a ciruit affects your safety. Simply that when you draw too much current from a line there is heat dissapated in the wire due to the resistance inherent in the wire. Things like joints along the way where they get made through a screw down are also a point of resistance. This resistance and heat when a high current is drawn can get to the point where it can cause combustion of other materials or at a minimum smoldering and the consequential smoke. This is why i hate extension cords. Inevitably people are cheap and without an understanding of the whole process by a cord and then because it has the receptacle connections think they can run any old thing on it.
If you take your heaters for example and run them on a thin gauge extension cord you will feel that extension cord getting warm.
This is also something which is not often mention either about the benefit of running 220v.
If you apply the same equation and say that your heaters were of the 220v type then P=V.I so we have 1500w / 220V = 6.8 amps. Note the current is halved. I aint gonna get into phases etc because to want to keep it simple so the others here dont go biting my head off because i am trying as best as possible to keep this basic.
So you need to think about deciding whether you have the finances and desire to do what you want or just what you need right now.
Remember the fundamental cost with any contractor is being on site. The additions to the scope of work are only then a function of the direct material and labor associated with it and margin. What you dilute by adding to the scope of work is his overhead to be on site. This is something people do not understand about the trades. We get a guy coming to service the gas stove or the dishwasher or refrigerator and we balk at the call out charge. We dont think of the time it takes the guy to get to us and the travel costs and the time back to where he was. Never mind his tools, training and motor vehicle costs right down to car washes and winshield washer. Whether he does one circuit breaker or 10 thats fixed. But we all are living in tight budget times so you must make the call for that.
As to what you put in i think you need to spell out a little of what direction you are going.
1) Now
2) Long term and do you want to cater for long term even if you do not do the whole thing.
If you do then you should spell out everything thats gonna be in this shop and lets estimate the power for each item
Just to help you
Think on machinery alone we generally have the following minimums
1) Drill press
2) Table Saw
3) Planner
4) Some have mitre saw or radial arm or even both. I know of some with two mitre saws and a radial arm saw.
5) Bandsaw
6) Jointer
7) Heavy duty router like 3.5 hp
8) Dust collector
9) shop vac
10) Heaters regardless of the type most have a requirement for electric except the woodstoves.
11) Lighting
12) Yes some of us have lathes.
13) Miscelaneous power tools and battery chargers and radio or amp.
14) Air cleaner or air scrubber what ever you call it.
15) Some have airconditioning which is another little power hog depending on its size.
Now there will be a difference between what the individual machines draw as far as current is concerned and here we get to the dreaded marketing lies that many of these tool and machine manufacturers play with and that is HP or horsepower. There is a mathematical formula to calculate the current from he HP given the voltage but i would prefer you look at the motor or specification of the machine for the actual current rating rather than rely on the marketing lies so i will not volunteer the Hp calculation just so errors are minimized.
There is a range for each of these machines and its the typical item that drives our machine prices. (Not in Canada. Here we get ripped for 1HP what the US pays for 3 or even more) So i am more refering to a purchase from say Grizzly or Delta than Craftex( Busy Bee).
You need to think about your wish list here and take into account your current machines.
This is not as ardous as it sounds. Most of us are pretty much in a narrow bracket and budget and common sense and our work we do drives it.
If the general hobbyist was a Karl making cabinets as an occupation then it would be different. In my case i tried to be middle of the road.
Dont be surprized by the fact that all this power quickly adds up but this is why i recommend a sub panel. When you start to add proper dust collection and consider that this unit will most likely be running with a machine and here you have to take your worst case machine which in my case is my jointer, then add lights and either heater or aircon and air cleaner then you have my typical maximum load. With my dust collector being 220V and my jointer being 220V i manage to get in under the wire when I am in either of the above states. Of course that will be when my dust collector is hooked up but that is what my design caters for. My panel is on a 60Amp breaker from the main house panel.
So i think i have done enough confusing or thought raising for the moment. There is no easy quick just do this answer. You need to digest this and discuss with Brian. Because where is he getting his power from for his shop? Decide on your priorities. There is a low cost short route here as a temporary interim solution there is a middle of the road and there is the full hog.
Enjoy i am now glad i am past this evolutionary point although i wish i had added even more circuits to my shop and i wish i had put them on the surface like others.
One thing for sure, if you get 220v make sure to run a receptacle to both sides of the shop. I had a layout planned and laid out the receptacles accordingly. Now i am sorry.
Good luck let us know what you decide and we can help some more.
Remember my Dads saying that echos in my ears hourly, "Act in haste and repent at you leisure"
Boy i hate that saying.