Selecting the best 240V receptacles for the garage

[TWX]

Hey everyone,

We just bought a new place and I'm the new proud owner of a block-construction three car detached garage, 24'x38' inside, with air conditioning/heating and plumbing for a bathroom. The electric is going to need some attention, since the old owner had all of his higher power equipment running three-phase through a converter and everything was hardwired, and there are no receptacles. There are four 240V breakers, one 40 amp (for the air conditioner), two 50 amp, and one 60 amp. There are three 120V breakers, two 15 amp for lights, and one 20 amp for long set of power strips. There is one empty breaker position.

Currently all that I have that's 240V is my old air compressor, which currently is wired with a NEMA 6-50 plug that is capable of being reconfigured for a NEMA 6-30 plug, which would also be adequate for the compressor. I have a second convertible NEMA 6-30/50 plug not installed on any equipment, and NEMA 6-50 plug that isn't convertible, also not on any equipment at the moment.

From what I've read, it looks like the only major improvement that I could make would be to go from the NEMA 6 series to the NEMA 14 series with an added neutral, or to the twist-lock style NEMA L6 or the NEMA L14 equivalents, if they're available in high enough amperage.

I have three questions- first, do the NEMA 6 and 14 have the same spacing for the two Hot pins and the Ground pin? If so, then wiring the two 50A circuits for the NEMA 14-50 receptacle and being able to plug the current NEMA 6-50 plugs in to those receptacles would seem to give me the most versatility. Obviously if they're not then perhaps I have to consider that.

Second, how common are the twist-lock plugs on equipment like welders and plasma cutters compared to the straight blade plugs, and do these connectors exist in the amperages I'll need?

Third, the previous owner left four switched fuse boxes that have fuses and switch controls for three wires, wired in a peculiar fashion probably due to the former three-phase setup. I'm thinking I can reuse three of these boxes to switch my 240V circuits, using two of the three internal paths for the two Hot wires and the third for Neutral, if I switch to the NEMA 14 setup. Does this make sense to anyone but me?

On another note, there is one thing I'm looking at for the AC/heater that I'm concerned about. The previous owner wired the AC unit using a sheathed wire bundle that has two additionally-sheathed wires and one bare wire, and the bare wire was used for the Neutral, and there is no ground. I'm thinking that I need to rewire, stringing a new, sheathed wire for Neutral, to then switch the bare wire to ground. Any thoughts on this?

 

[mrb]

show me one piece of garage equipment that uses 120/240 4 wire.

i dont think a nema 6 will plug into a nema 14

nema twistlocks only go up to 30 amps. there are 50 amp twistlocks, but theyre big and expensive, theres also pin and sleeve which is even more expensive.

dont ever fuse or switch the neutral

 

[TWX]

Well, after posting my thread last night I found more information that makes it look like Miller is now using NEMA 14 as their default plug on their welders.

I'm thinking I'll use 6-50 for the first 50 amp circuit, I'll place both 6-50 and 14-50 for another receptacle and label them for only using one at a time for the second 50 amp circuit, and use a 14-60 for the 60 amp circuit.

Now all I have to do is to determine placement...

 

[sberry]

Second, how common are the twist-lock plugs on equipment like welders and plasma cutters compared to the straight blade plugs, and do these connectors exist in the amperages I'll need?

Dont ruin the machines by fooling with the cords, get the right recepts. Use 6-50. Almost any welding machine you use at home can run on this circuit.

 

[tonycastec]

Thanks for starting this thoughtful thread.Please ignore the 3-wire guys .The future is 4 wire. You are on the right track. Combining neutral and ground(3 wire) is not a great practice.It was an expedient in WW2 to save copper.
You may find it interesting to follow this thread:
http://garagejournal.com/forum/showthread.php?t=135763
Duck for incoming salvos from the 3 wire guys!

 

[Stuart in MN]

Thanks for starting this thoughtful thread.Please ignore the 3-wire guys .The future is 4 wire. You are on the right track. Combining neutral and ground(3 wire) is not a great practice.It was an expedient in WW2 to save copper.
You may find it interesting to follow this thread:
http://garagejournal.com/forum/showthread.php?t=135763
Duck for incoming salvos from the 3 wire guys!

As mentioned by mrb a year ago, most 240vac tools such as air compressors or welders don't need a neutral wire, only two hots and a ground.

A neutral wire is required for a device that also has 120vac power requirements, like a kitchen stove.

 

[tonycastec]

Thanks for raising this issue Stuart. You are correct -"240v doesn't need a separate neutral & a separate ground" is the old propaganda. Think about it... why does 120v get a separate neutral and ground but not 240v? That is why the old 3 wire 240v receptacles and plugs are obsolete -even for 240v water heaters that technically do not 'use' a neutral.Similar reasoning for 120v 2 wire receptacles.
The 4 wire 240v protocol(NEMA 14-**) is the current code for new installations/construction. Other countries that use 240v (like U.K.& colonies)have had separate ground and neutral since the 1960's . They even have a fuse in every plug too -and breakers for every circuit like we do. That may be the next money-maker for the electrical equipment manufacturers here -a fuse in every plug -kinda like a 'chicken in every pot'? Imagine the money they would make if we all had to change to fused plugs.

 

[Charles (in GA)]

Thanks for raising this issue Stuart. You are correct -"240v doesn't need a separate neutral & a separate ground" is the old propaganda. Think about it... why does 120v get a separate neutral and ground but not 240v? That is why the old 3 wire 240v receptacles and plugs are obsolete -even for 240v water heaters that technically do not 'use' a neutral.Similar reasoning for 120v 2 wire receptacles.
The 4 wire 240v protocol(NEMA 14-**) is the current code for new installations/construction. Other countries that use 240v (like U.K.& colonies)have had separate ground and neutral since the 1960's . They even have a fuse in every plug too -and breakers for every circuit like we do. That may be the next money-maker for the electrical equipment manufacturers here -a fuse in every plug -kinda like a 'chicken in every pot'? Imagine the money they would make if we all had to change to fused plugs.

The 240 in the UK is like our 120. It is a hot to a neutral, there is no way of splitting it into anything less than 240. 240 in the UK has a neutral for the same reason our 120 has a neutral, to make the remainder of the circuit. In the US, 240 doesn't need a neutral, except for the few appliances that use it for timers, electronics, fans and motors internally that are powered by 120. Why they don't just use timers, electronics, fans and motors that use 240 is the question everyone should ask.

The fuse in the plug is actually a good idea. The circuit breaker in the panel protects the wire in the wall, but the appliance usually has a smaller cord and the fuse in the plug is designed to protect this smaller cord and device.

Water heaters should not be on a plug and cord. Generally the connections in the heater are not designed for cord wire (that very fine stranded stuff used in cords) and code says that if the appliance is not designed for or approved for cord wire, you cannot use it.

Welders generally do not use a neutral, their manufacturers are smart enough to make a multi-voltage device that runs on whatever you put in it in most cases nowdays. I cannot think of anything in a shop that uses a neutral with 240.

Charles

 

[tonycastec]

The question "why do you need a neutral & a ground with 2 pole 120=240v systems is one best addressed by the NEC & NEMA. Why did the make all the 3 wire 240v receptacles obsolete if separating neutral and ground wasn't a good idea? Why go to all the trouble of the new 14-** system,if it is unnecessary?

 

[Stuart in MN]

I think you're getting your NEMA connectors confused. NEMA 14 connectors took the place of the old NEMA 10 connectors, and are used for things like kitchen stoves or clothes dryers that have both 120 and 240vac requirements. NEMA 6 connectors are used for 240vac only devices like welders or air compressors, and are still in regular use. http://en.wikipedia.org/wiki/NEMA_connector

 

[Norcal]

show me one piece of garage equipment that uses 120/240 4 wire.

i dont think a nema 6 will plug into a nema 14

nema twistlocks only go up to 30 amps. there are 50 amp twistlocks, but theyre big and expensive, theres also pin and sleeve which is even more expensive.

dont ever fuse or switch the neutral

There are circumstances where switching the neutral is permitted......

The question "why do you need a neutral & a ground with 2 pole 120=240v systems is one best addressed by the NEC & NEMA. Why did the make all the 3 wire 240v receptacles obsolete if separating neutral and ground wasn't a good idea? Why go to all the trouble of the new 14-** system,if it is unnecessary?

It used to be permitted to ground the frames of ranges & dryers to the neutral, it is still OK in existing installations, but it was NEVER allowed anywhere else. That should have been done away with 50 years before it was, in the NEC.

 

[djmartins]

Thanks for starting this thoughtful thread.Please ignore the 3-wire guys .The future is 4 wire. You are on the right track.

Yes, but we are worried about RIGHT NOW and RIGHT NOW you aren't going to find a welder or compressor that needs 4 wires.
Use 6-50s for high amp stuff and 6-30 for the 30 amps stuff.
Now if you have some welders and compressors from the future you might have to do something different.....