S280 shelter electrical system

Going to try to fire up the electrical system in the shelters I got for our Co Communications board this weekend. These are actually print shop shelters (darkroom/typeset in one unit and print press/paper cutter in the 2nd shelter).

To the right/curb side of the door on exterior is a milspec electrical connection. 4 terminal. Inside is a 125amp breaker panel 60hz. Looks like all equipment is (including the Heat/AC units) is single phase 60hz. The genset pigtails are also 4 strand - wires are marked ground, L0, L1, L2.

I can use a MEP003 (terminals are marked same as the wire pigtail). Or I can use a MEP004 (termials are marked L0, L1, L2, L3). I'd prefer to use the MEP004 as easier to access/hitch up.

Question: Are shelters wired for 3ph supply and crossconnect inside the shelter breaker panel to balance the load? Or are they wired single phase? What standard supply voltage?

How hook up the pigtail for correct supply to the shelter for MEP004? What setting on the genset control panel and connection board?

Or is the entire thing 1ph (should use the MEP003?

A WAG but a four pin connector implies single phase (two hots, neutral and ground). You need five pins (three hots or phases, neutral and ground) for three phase.

but an easy answer is to check the box inside, I'm sure the cover comes off easily.

What does the neutral do in a 3 phase circuit?

phil2968 said:

What does the neutral do in a 3 phase circuit?

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If all of the loads are three phase, nothing. It is typically the "grounded" conductor, used to carry the unbalanced load, for the 120 volt single phase.

Neutral is the same on three phase as it is on single phase, it lets you get two voltages, either going from leg to leg (higher voltage) or leg to neutral (lower voltage).

For a WYE setup, you typically get 208 volts from phase to phase, and 120 volts from phase to neutral.

For a high side delta, you get 240 volts from phase to phase, and one phase has a center tap to neutral to give 120 volts.

For anyone using three phase for general purposes (not for dedicated machines only) neutral is important.

Also neutral is not the 'grounded conductor' as it may or may not be grounded from the power source.

PeterD said:

Also neutral is not the 'grounded conductor' as it may or may not be grounded from the power source.

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It is typically the grounded conductor.

Every S280 I have ever come across with air conditioners was 208 volt 3 phase. That configuration uses 3 hot phases and a ground, no neutral. MEP002 and 003 are set up like this.

I was expeceting to see a 3ph A/C & heater unit which is what has me confused.

NEIOWA said:

Going to try to fire up the electrical system in the shelters I got for our Co Communications board this weekend. These are actually print shop shelters (darkroom/typeset in one unit and print press/paper cutter in the 2nd shelter).

To the right/curb side of the door on exterior is a milspec electrical connection. 4 terminal. Inside is a 125amp breaker panel 60hz. Looks like all equipment is (including the Heat/AC units) is single phase 60hz. The genset pigtails are also 4 strand - wires are marked ground, L0, L1, L2.

I can use a MEP003 (terminals are marked same as...?

Click to expand...

MEP003 also are L0, L1, L2, L3