[SSBN657]

I have a 5,000w Coleman Powermate generator. I just installed a Gould transfer switch. Now I just need to connect them together. The Coleman requires an L6-20P 3 prong and the Gould requires an L14-20R 4 slots. I cannot find any such cable. I can buy a Levitron L6-20 plug and a L14-20 receptacle and 10 feet of 12 gauge wire to make a cable but what do I need to know to be able to do this? The 3 prongs to 4 slots has me confused... Any suggestions?

[tkrussell]

The L6-20 means the output will be 20 Amps 240 Volts, 3 wire with two hots and one equipment ground.

The L14-20R is a 120 and 240 volt input, two hots, one equipment ground, and a neutral for the 120 volt.

You need a generator that can give an output of 120 and 240 volts in one receptacle, such as the L14-20.

Along with the L6-20 R you have on the genset, there probably is a 5-15R or 5-20R, for separate 120 volt output. Perhaps you can do something with that, but anything doe will not be proper, violate the UL listing of the genset, therefore I cannot offer that advice.

Perhaps a repair shop that works on that genset can modify it for you.

[KISS]

You seemed also to indicate that the generator input connector does not have prongs. This would not be good.

What we don't know is if the generator creates two 120 circuits 180 degrees out of phase.

Would you happen to know if the transfer switch switches the neutral?

[tkrussell]

Kiss a genset has output receptacles, not input.

Why do you insist that 2 - 120 volt circuits off an Edison 3 wire system is 180 out of phase, when it is only one phase.

Why would a switched neutral make any difference on the genset output?

[KISS]

OK, I misinterpreted,

the Gould requires an L14-20R 4 slots

An is "singular". 4-slots is plural. Confusing isn't it? I "A$$ U ME"ed that the singular connector was the connection to the generator and R (Receptacle) is the wrong gender.

I can buy a Levitron L6-20 plug and a L14-20 receptacle and 10 feet of 12 gauge wire

The above sentence makes sense for a generator cord set.
The singular plural thing above is not right. I missed that the cord is correct, but the initial statement is incorrect English. It was interpreted as one l14-20R because of the word an with 4 slots (receptacles) of an undetermined configuration.

The use of a generator input connector was never mentioned. That connector usually has pins because you essentially plug the house into the generator.

Why do you insist that 2 - 120 volt circuits off an Edison 3 wire system is 180 out of phase, when it is only one phase.

If the 120 legs were not 180 deg out of phase they would never add to 240 V, would they?

If the 120 V legs were in phase, only the current would increase. Yes, I agree that the primary is fed from single phase. The secondary is, two 120 V legs 180 deg out of phase. It's not two phase because the ends are tied together.

Why would a switched neutral make any difference on the genset output?

We had a post a while back where a guy did a fair amount of research and talked to a generator company. In his post, the generator company said a transfer switch that switches the neutral would be the best choice.

Remember, there is this issue about ground rods and neutral to ground bonding of the generator set.

If the neutral is switched, the generator can stay in one configuration where the neutral and ground are connected at the generator. (I guess this only makes sense when the generator is supplying the entire panel. i.e. A large genset with it's own grounding system. I'm not sure now if it makes sense for a small generator)

If the neutral is NOT switched, then you need two different configurations of the generator.

A) Ground connected to Neutral at the generator when operated stand-alone. One method to do this, because you don't typically operate 240 pieces of equipment stand alone is to use the twist lock, paint it bright orange, and connect ground to N in the twist lock.

When operating it stand alone, you insert the twist lock and use the 120 receptacles in stand alone mode.

B) When operating it as a backup power source, the 4 wire receptacle is used to connect to the house and ground and neutral are not connected at the generator, but are connected at the panel. This preserves the ground/neutral bond at one place.

The method is simple and elegant.

Thanks.

[KISS]

Deeper thought.

Let's assume for the moment that we have a DC distribution bus, N is our reference, L1 reads 120; L2 would have to read what in order for L1+L2 to be equal to 240.

Meters basically read a value - a reference or Vm = V - Vref.

So, one LEG reads 120 V with respect to neutral.

In order for 240 = 120 - Vref to be equal to 240, Vref with respect to N must be -120 V, so

240 = 120 - (-120) ; this is correct

If these were AC voltages, this would imply 180 deg out of phase.

e.g. V = 150*cos(theta)-150*cos(theta+PI)

cos(theta) = 1 and cos(theta+PI) = -1

The 150 is the zero to peak voltage with respect to neutral and remember how our meters work; Vm = V-Vref

PI is 180 deg; therefore the AC voltages are 180 deg out of phase with respect to neutral.