Electrical Question - Table Saw Wiring

[gunrunner0]

I recently purchased a new to me Delta Unisaw 36-L352. My question relates to the switch wiring. The motor on the saw is a Single Phase 3 HP motor, rated at 230V and 12 amps per the tag on the motor. It has a factory magnetic switch with wire going from the switch to the motor as I would expect. However the wire feeding the switch runs to a transformer (picture below) and then out of that to a 15 amp 250V plug. Can anyone tell me why this was wired this way? Can I simply get rid of the transformer and run a 230V 20 amp?

I will likely be running a new 240V circuit for this and just want to make sure I get it right.

Edit to add:
I've looked at the manual on Delta's website, it doesn't have much discussion about the switch wiring and no cord listed on the parts diagram.

I really don't know much on this type of electrical wiring.I assume the prior owner had the transformer installed after purchase in order to adapt the voltage to accommodate the motor, but I can't figure why there's a 250V plug if they were running it on 115V.

 

[Creedmoor]

I would say the last owner only had 120V available.
Eliminate it and wire through the magnetic starter switch.

 

[BiscuitsandGravy]

What is hooked up to these connections on the transformer...

H1-?
H2-?
etc...

 

[edwea]

It may have to do with some safety feature or thermal cutoff type of thing. Without tracking the wires around, to see what they go to, it may be hard to know. Why are you thinking of rewiring it? Not working?

 

[Frosty]

A lot of saws have a safety feature that will default to an “off” switch. Say you’re using the saw and the power goes out, the switch will return to off so the saw doesn’t restart when the power comes back on.

 

[xwing]

You mention a 15 amp 250V plug. What is it, a NEMA 6-15P? IMO just run 230V / 20A on the circuit (aka 12/3 wire & 2Pole / 20A circuit breaker), and install a receptacle that matches the plug. Or if you think you may ever upgrade at some point, run 10/3 wire and 30A breaker. Unless the saw isn't working properly, I wouldn't mess w/ trying to bypass the saw's internal transformer.

 

[gunrunner0]

What is hooked up to these connections on the transformer...

H1-?
H2-?
etc...

Well I pulled the cover off of the transformer. Short answer to your question: Nothing.

In the box hot from switch is wire nutted too hot from the plug, same for neutral and ground (which is also grounded to the box). The transformer is completely bypassed. Transformer pigtails X2/X3 were wire nutted together as were H2/H3. X1, X4, H1, and H4 were all stripped and showed evidence of previously being in a wire nut, but were just loose in the enclosure. All the wire nuts were tight and there weren't any extra laying the box.

I guess that explains the 250v plug. I don't know what they did here but my theory is they started with it on 115v through the transformer and then changed back to 230v and just used the transformer enclosure as a junction box.

I attached pictures below incase my description didn't make sense.

My only concern at this point is figuring out why there aren't two hots running into the switch, but I assume they're using white as a second hot leg. I'll pull the switch apart tonight to confirm.

 

[gunrunner0]

It may have to do with some safety feature or thermal cutoff type of thing. Without tracking the wires around, to see what they go to, it may be hard to know. Why are you thinking of rewiring it? Not working?

I don't have any outlet that will take this style of plug at this point. I have not tested the saw yet, I bought it at auction last week and just got it home yesterday. Rewire makes sense to me to get rid of the transformer, which in my mind will allow the saw to perform better and also simplify the system.

You mention a 15 amp 250V plug. What is it, a NEMA 6-15P? IMO just run 230V / 20A on the circuit (aka 12/3 wire & 2Pole / 20A circuit breaker), and install a receptacle that matches the plug. Or if you think you may ever upgrade at some point, run 10/3 wire and 30A breaker. Unless the saw isn't working properly, I wouldn't mess w/ trying to bypass the saw's internal transformer.

My plan at this point is to run a new circuit. Saw will be in the garage which is also where the panel is located, making a new run relatively easy. I'll most likely run 10/3 to allow for future upgrade.

It is a NEMA 6-15P plug. I ordered a 250v rated extension cord with the same plug as that appears correct for 20 amp/250v applications, to cut apart and use for a new cord. If I can get the circuit components locally, hopefully I can get this thing running this weekend.

 

[xwing]

I guess that explains the 250v plug. I don't know what they did here but my theory is they started with it on 115v through the transformer and then changed back to 230v and just used the transformer enclosure as a junction box.

That's the only thing that makes sense. It was originally wired for 115v... I was trying to figure that out too...

It is a NEMA 6-15P plug. I ordered a 250v rated extension cord with the same plug as that appears correct for 20 amp/250v applications, to cut apart and use for a new cord. If I can get the circuit components locally, hopefully I can get this thing running this weekend.

Shouldn't be hard. All the stuff you mentioned should be available at Home Depot or Menards pretty easily. 6-15R is pretty common. So is 10/3. And 30a Breaker for most electrical panels (unless you have something really uncommon.)


Sounds like a fun mini project.

 

[gunrunner0]

That's the only thing that makes sense. It was originally wired for 115v... I was trying to figure that out too...



Shouldn't be hard. All the stuff you mentioned should be available at Home Depot or Menards pretty easily. 6-15R is pretty common. So is 10/3. And 30a Breaker for most electrical panels (unless you have something really uncommon.)


Sounds like a fun mini project.

Thanks for the insight.

Yeah, I'll run conduit so probably stranded wire but I think I have some 10/3 leftover from remodeling the house and if there's enough I'll probably go that route. have to check the stockpile. I wasn't sure how easy it would be to get 50 ft of stranded wire locally, but looks like menards stocks it.

Square D QO panel so no problem on finding a breaker.

 

[xwing]

Thanks for the insight.

Yeah, I'll run conduit so probably stranded wire but I think I have some 10/3 leftover from remodeling the house and if there's enough I'll probably go that route. have to check the stockpile. I wasn't sure how easy it would be to get 50 ft of stranded wire locally, but looks like menards stocks it.

Square D QO panel so no problem on finding a breaker.

Conduit? Are you running it on the wall face? Or just a gluten for punishment? I used to live in Chicagoland and did a couple of big remodels / additions in my house. Wow, I really hated running & bending EMT inside the wall. I like it much better here where Romex is code compliant. I wired 400A service / whole house last year, probably 15,000 ft of wire.

Wire (stranded, solid, NM-B, etc...) is a lot more available now than it was about 12 months ago. Some of the less common gauges are still hard to find; but 10awg or 12awg is no problem. And QO is my go-to as well; Menards stocks all the standard breakers for it (although again about 18 months ago, they were really hard to find.)

 

[gunrunner0]

Conduit? Are you running it on the wall face? Or just a gluten for punishment?

Yeah, the garage is drywalled and has a 7' ceiling so I figure the conduit is the way to go. Looks better and less chance of damaging wire while swinging around lumber etc. Luckily it's a pretty straight run so I won't have to do any bends. Just cheat with a couple elbows.