Small gennie question

JB Earl · May 2, 2023

Maybe looking for Guy Holt here, but I’m wondering how the 60amp bates conversion works on small generators. I occasionally rent the Honda 6000 from building suppliers and there is no way to get that many amps from one circuit. It seems the hot legs are two 120 V circuits. Are there any small gennies that can supply enough amps for a 5K Without the Bates mod?

Daniel Klockenkemper · May 2, 2023

The simple answer is that they don't. For the Honda EU6500 or 7000 generators, the model number represents the possible momentary peak load. The maximum sustained load is 5500W/45.8A according to the spec sheet, but you should still allocate some some headroom for good measure. The modified generators I've seen have 50A circuit breakers on them.

60A is just the next size up for the cable/connector, which does help to ensure that the cable is less likely to be a limiting factor.

JB Earl · May 2, 2023

Thanks Daniel, i’m not so much worried about the physical connections, I’m trying to figure out why even on the 10,000 W generator I can’t get a single 50 amp 120 V circuit. They seem to be limited to something like 41 A

Edited May 2, 2023 by JB Earl

David Mullen ASC · May 2, 2023

This was an answer on Quora:

In the USA, most small generators are 120/240 volt split phase, and 10 KW would then be about 10,000 / 240 = 42 amps. This would have 2 hot legs and a neutral. In most cases, each hot leg will only handle half of the full generator power. So if you have a single 120 volt load, it would only be able to pull the same 42 amps, and only handle 5,000 watts on either 120 volt hot leg. Each output is just 1/2 of the generator’s power. To use the full 10,000 watts, it would need to use both 120 volt outputs, or run on the full 240 volts across both legs.

At 10 KW, some models might be a 3 phase design where it produces 3 legs of 120 volt at 120 degrees apart in phase. Across any two phases would be 208 volts. That 10 KW would be 10,000 / 120 = 83 amps, but then divide by 3 and you get about 28 amps on all 3 phases. This will have the same limitation as the split phase above. Each leg can only produce 1/3 of the full generator power.

JB Earl · May 2, 2023

Thanks very much David. So it looks like the bates plugs on small gennies is not just a modification, but a completely different generator

Guy Holt · May 3, 2023

On 5/2/2023 at 2:36 PM, JB Earl said:

I occasionally rent the Honda 6000 from building suppliers and there is no way to get that many amps from one circuit. It seems the hot legs are two 120 V circuits. Are there any small gennies that can supply enough amps for a 5K Without the Bates mod?

The Honda EU6500s or EU7000 outfitted with 60A Bates receptacle are standard Hondas (nothing special about them.) Like all Honda EU6500/7000s, they have two inverters that can be operated either in parallel or in series. When the power select knob is set for 120/240V, the two inverters are in series to provide split-phase power (120V line-to-neutral and 240V line-to-line through the 30A 4-pin Twist-lock receptacle). When the power select knob is set for 120V only, the two inverters are in parallel to provide a single large 120V circuit. In 120V only mode the maximum output is 50A (regardless of what kind of Bates receptacle is put on the machine). The only way to get a true 60A/120V circuit is to use a small 240V-to-120V step-down transformer on the 30A 4-pin Twist-lock receptacle when the power select knob is set for 120/240V.

Which means any Honda EU6500 or EU7000 without the Bates modification (even ones from building suppliers) can power a 5k through its 4-pin 240V Twist-Lock receptacle with a 240V-to-120V step-down transformer like the one we sell with our HD Plug-n-Play Pkg. Our transformer/distro is designed to step down the 240V output from a a dryer receptacle or EU6500/7000 to a 60A/120V circuit, or a range receptacle or paralleled EU6500s/7000s to a 100A/120V circuit. As an added feature they can boost the voltage to compensate for voltage-drop over a long cable run so that you can operate the generator/s out of the back of the grip truck or from around the corner of a building where it won't be picked up on your audio tracks.

For more details about these issues see an article I wrote for our company newsletter that explains the electrical engineering principles behind these issues and how to resolve them. The newsletter is available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer, ScreenLight & Grip

Guy Holt · May 3, 2023

On 5/2/2023 at 4:11 PM, Daniel Klockenkemper said:

The maximum sustained load is 5500W/45.8A according to the spec sheet, but you should still allocate some some headroom for good measure. The modified generators I've seen have 50A circuit breakers on them.

60A is just the next size up for the cable/connector, which does help to ensure that the cable is less likely to be a limiting factor.

The Honda EU6500 and EU7000 are capable of sustaining up to 6750W of continuous load through its 240V twist-lock. Like a car, Honda engineered a single base model of the EU6500 and EU7000 for the world market that they then customize for the different national markets. The difference between the various national models is primarily in the power output panel, which is configured according to the electrical system and prevailing codes of the country (that also affects its rating) in which the generator will be sold. For the US market, Honda distributes the generator with a predominantly 120V power output panel that does not provide full access to the power of the generator which is 7650W. To demonstrate this is the case all you have to do is look at the wiring schematic of the UK model - the EU70i. Where the countries that make up the United Kingdom have not conformed entirely to the European Union standard of 230V, but still generates 240V power, the UK model is a good indication of the true generating capacity of the EU6500 an 7000 models sold in the U.S.

The difference between the two machines is in the circuitry of the power output panel and electronic governing system. Where we have a fairly complicated system of 20- and 30A 120V circuits, as well as a 30A/240V circuit, as well as a voltage selector switch to switch between them, and a 50A master breaker to protect the circuits in 120V mode; the UK model, by comparison, is very straight forward with three 240V receptacles wired in parallel

The three receptacles of the UK model have no fused overload protection where we have 20- and 30A fuses on our power output panel. According to Electrical Codes, that can only be the case if Honda has engineered an electronic circuit breaker into the microprocessor controls of the inverter module so that current is shut off to the receptacles if the generator is overloaded. Sure enough, the manual states that the generator has an electronic circuit breaker. rated for a continuous load of up to 7650W. With the EU version of the EU7000is, when you exceed 7650W the power cuts off to the receptacles. To re-energize the receptacles, you must shut the machine completely off and turn it back on again.

It makes perfect sense that Honda would engineer a continuous load capacity of 7650W into the base model of the generator when you consider the electrical systems of the UK countries. Where we have 15- and 20A circuits, they have 13-and 16A circuits. Two 240V/16A circuits provides a total of 7650W (3840W/circuit x 2 = 7650W) which is what we found that the electronic circuit breaker in the inverter module of the EU7000s distributed in the US are also set for. Our 60A transformer/distro taps the inverter as it was designed for the EU market, which gives us access to the full power designed into the generator for these markets. Our 60A transformer/distro will then step-down the 7650W at 240V to a single 60A/120V circuit that is capable of powering bigger lights, or more smaller lights than could be operated on the generator otherwise.

For more details about these issues see an article I wrote for our company newsletter that explains the electrical engineering principles behind these issues and how to resolve them. The newsletter is available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer, ScreenLight & Grip

JB Earl · May 4, 2023

thanks Guy, I appreciate the detail. So Bates mod then eliminates the 20A breaker restrictions at 120v then...in an ideal world I'd love to run 3 1200w fixtures, but we're limitied to two 20a/120v circuits I think...

Edited May 4, 2023 by JB Earl