Large Sawstop installation options? (electrical question)

[Mike Heaney]

Hi there,

This is not intended to be a gloat (and there are no pictures!), but I have just been gifted a brand new Industrial Sawstop- model ICS73230:7.5 hp, 3phase, 230V,17.8 A

I have also been given the 3 phase converter hardware that was used in the previous install (a Temco series 6000 21kw RPC and attendant control box and mag switch box).

It seems to me that this converter is significantly larger than I really need- which would not be a problem other than it seems to need a 120amp breaker for startup. My barn workshop has a 220/240v, 100 amp subpanel, so it seems I have a capacity problem. So far I have considered:

1. Running an additional line to the shop to be the dedicated single phase supply for the 3 phase converter
2. Selling the Temco unit and purchasing a smaller one that will work with my subpanel
3. Changing out the motor to a smaller 3 phase or even a 5hp single phase Sawstop motor.

This is my first 3 phase machine. There is a fair chance I will want to add a big old jointer and maybe planer to the shop mix in the future and they could be 3 phase, but it is highly unlikely I would ever be running more than one machine at a time.

I'd appreciate any thoughts and suggestions on how to proceed from here

thanks in advance

Mike

[Charles Lent]

That's the peak recommended breaker size, but you should be fine running it on 100 amp, at least for now with only one 3 phase tool. If you don't try to start several tools at once you should also be OK. In fact, you should be OK if you run a dust collector and the saw at the same time. You will likely only need the 125 amp source if you plan on running many 3 phase tools at the same time. Always start 1 tool at a time and let it come up to speed before trying to start another and you should be fine for a 1 man shop.

Charley

[Mike Heaney]

Thanks Charley- just want to check that I understand your suggestion here. I would set up as follows
1. Breaker on house panel for the sub panel =100amp
2. Breaker on input side of sub panel in barn= 100 amp
3. Breaker on sub panel to feed the RPC= 100 amp

and even if I am running a few other things at the same time ( lights, 20amp heater), the current spike from the RPC on startup and on load machine startup would usually be low enough that I would not trip any of the breakers?

thanks again

mike

[Charles Lent]

You don't need the main breaker on the sub panel. The 100 amp breaker at the main panel is all that is necessary, unless you want it for some reason. Having multiple breakers of the same rating in series will cause the weakest breaker to trip whenever an overload occurs, so until you upgrade the line to the sub panel and have progressively smaller breakers in series you will have to deal with this. It's not a big issue if you are careful with what you start up and use at the same time. Most shops with RPC start them first thing in the morning and then leave them running all day. Then they just start up the rest of the machines and shut them off as they are needed, while keeping in mind how many they have running at any given time. Don't run the heater or anything else except maybe the lights when you are starting the RPC. This is not the ideal way, but until you can upgrade the service to the sub panel you should be able to get by and do it safely.

Charley

[Chris Padilla]

You might contact SawStop and ask them the cost for the change to a single-phase. It could be easy or difficult to swap motors. Cost might be recouped selling the motor and converter. OR you might be heading down the slippery slope of access to "cheap" 3-phase motors in the future but at the cost of likely needing to upgrade the service to your shop.

[Mike Heaney]

Thanks Chris and Charley,

I am going to chat with my electrician as he installed the line and the sub panel for me- I am not sure which size feed he used in the end, if it is big enough, we might be able to swap over to a 125 amp breaker safely. Anyway, I will see what he recommends and let you know how I get on!

Mike