3 phase (delta) power to single phase space heater

Question

I bought a 240V single phase, space heater for heating up a warehouse space. The warehouse has 240V power in a delta configuration (no neutral). My understanding is that in a delta configuration, the line voltage between any two phases is the same as the phase voltage, in this case, 240V. So I should be able to wire the the heater between any two lines, right?

Answer 1

Here's what 3-phase delta looks like.

This happens to be 240V and uses the common 3-phase colors of black, red, blue.

It's that simple, folks. 3 phases, No Neutral.

One error of belief is thinking every service must have a neutral. It doesn't. This was Tesla's genius.

Delta is used in industrial facilities where a few tools need a medium amount of power for a few larger tools. It would be rare to see lighting or other minor loads run off it. A motor which takes 240V 3-phase can typically be jumpered to also work on 480V 3-phase, and that is much more efficient to distribute. I would never install 240V today, I'd install 480V.

Obviously there's only one voltage. Pretty straightforward. Now what's this?

It's the exact same thing. The only difference is using alternate colors. The point here is that any color may be used (except white, gray or green) including orange. NEC doctrine is the electrician is expected to measure the circuit to determine voltages. Prince fan? Use Purple Pink Black.

Hook your heater between any two hots.

They are all 240V. Done.

The only other issue is balancing. If you have several loads, try to put them on alternate phases so you load the 3 phases evenly.

We're done here.

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So what's this Other Thing then?

This thread is dominated by discussion of some other system which is not relevant to OP. It's a red herring. But since it keeps coming up, let's talk about it. This is "high-leg" or "wild-leg" delta, which is a clever rearrangement of delta to get 120V single-phase loads also - to avoid the cost of a separate 240/120V single-phase service. See how a neutral has been added halfway down a phase.

If you want to use 120V appliances, this only works on 240V delta.

Notice two mandatory wire colors. Of course, neutral must be white or gray. The "wild leg" - with much higher voltage to neutral - must be orange. It's one of very few cases where a "hot" color is mandated. However in any other circuit, you can use orange for any hot, and that's exactly what happened in our second example. That means if you see black-red-orange-white, it could be anything including 600V wye. You better test it.

So when someone says "Delta" they do not mean "wild-leg delta". They mean "delta". Don't go buying something that needs 120V or 208V expecting it to be there in delta service. It won't be unless they specify wild-leg/high-leg.

All the 120V loads load up the A-C phase. If there's a desire to run a significant number of 120V circuits, 208V "wye" 3-phase does a better job of it, while allowing loads to be balanced. If lighting is the primary load, 480V "wye" is a "swiss army" voltage, allowing 240V/480V motors to run in delta connection and lighting to work in wye, using a hot-neutral 277V connection.

Answer 2

Yes, you are correct. You can wire the heater across any two of the three phases.

Answer 3

My understanding is that in a delta configuration, the line voltage between any two phases is the same as the phase voltage, in this case, 240V.

'phase voltage' is not a great term. It would generally be interpreted as phase-to-neutral voltage, but you said you have no neutral.

3-phase delta works like this:

If you're sure you have no neutral, you can ignore the neutral in the diagram and the 120 and 208 that it can provide.

So I should be able to wire the the heater between any two lines, right?

You should be able to wire the heater between any two hots, Yes. Measure voltage first to make sure it's 240 like you expect.

Answer 4

If this is a DELTA usually the B leg is colored Orange and will be 2x the standard voltage. WYE connected systems all 3 legs have the same voltage. Verify the voltages prior to making any connections!!! Added for all those that have not worked on deltas with single phase. By code the system has to be grounded and can create the wild leg. Use of a wild leg will double the voltage to ground when used with single phase. Code requires equipment like this to have the highest voltage rating not dual voltage because of the high leg. At least this is code in the U.S. that has not changed for years. So ether there is a wild leg or a corner grounded. A single phase load would need to be on one of the grounded legs.