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Wiring a mobile specialty truck that will be potentially be

drawing 9000 watts. I have...
Wiring a mobile specialty truck that will be potentially be drawing 9000 watts. I have a 10,000 watt generator that has 2- 30Amp 240 plugs, 1- 30Amp 120 plug and I'm feeding a 100Amp breaker panel and 10 circuits.
I'm worried that one 30Amp side on the gen won't power everything in the truck and am wondering if I need to run both 30Amp runs (and potentially the 30Amp/120) into the panel somehow.
Any help would be appreciated!
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Answered in 3 minutes by:
8/29/2017
George Smith
George Smith, Master Electrician
Category: Electrical
Satisfied Customers: 274
Experience: Superintendent at Electrical Solutions and Data
Verified
Hi this is George. What are you feeding with the 120v feed? And what is the demand of those devices?
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Customer reply replied 2 months ago
The AC is 120V

Give me few minutes to look at everything!

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Customer reply replied 2 months ago
Also, there are no devices that draw 240 V

What are you going yo use on the 100 amp panel

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Customer reply replied 2 months ago
My hope was to tie the generator to the 100Amp panel and distribute all devices off of it. I have a list of everything that's going on the truck. Let me find it.

What are you using the 240v for?

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Customer reply replied 2 months ago
There are no 240 volt appliances. My plan was to feed the panel with it and drive the 120 circuits.

You should not have a problem with most deices. Without knowing what you have it's hard to say!

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Customer reply replied 2 months ago
George, are you saying that one 30Amp/240 run into my panel is sufficient? I'm not sure that's correct is it? Assuming each side leg of the 240/30Amp will feed all devices, it appears that I'll be exceeding the 30 Amps.

that is why I asked you what are you running ?

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Phil
Phil, Mechanical Engineer
Category: Electrical
Satisfied Customers: 8,824
Experience: Retired electrical contractor, 51 years experience.
Verified

Hello, there are two issues....both important.

Always size a generator at twice its full load rating... they will not last at all well if run at their full load rating. Something like a car that will do 125 mph top speed.... it won't last a full day at 125, but it will last 10 years at 60 mph.

Secondly. when figuring loads, we add up all of them, then divide by what we call a 'diversity factor' since it is rare that all loads will be running at the exact same time..... diversity is commonly 60% of the total load.

.

Third, heavy motors, such as AC units take 3 times their full load rating for the first 2 seconds in order to start... the generator MUST have that reserve capacity. If you have it sized at half of the load figuring in the 60% diversity it would normally be enough to allow for motor starting.

.

Let me know the full details of your load (watt ratings on each appliance) and your guess on how many minutes per hour it will be running. We can go from there.

.

Important note about RATING my work:

I am a retired mechanical engineer and HVAC/electrical/ refrigeration and boiler contractor... with 56 years in this business. The last 20 of those years consulting for major firms nationally..

.

All I ask is please respect me and my input by selecting the***RATING LINK***at the top of your page, that is the only way I am credited through the site.Rating does not affect your charges nor ability to refund if not satisfied.

.

If you need to be coached through a full diagnosis/repair,and wiring etc. for up to two days, and wish to be trained to use test instruments...... that goes well beyond' Just a simple Answer' of course, and goes beyond what most other experts here offer.....rate my simple answer so far positively.. and I will deliver that training and coaching to you All on the same dime so to speak.

.

Lacking a positive rating I can spend days helping a person at my own expense and loose my shirt,shorts and socks on the deal.

.

Attach a close up photo of the wiring diagram glued to the inside of the blower access door and I will mark it up with troubleshooting instructions then follow up with step by step training and coaching until you have a solution.

.

Photo must be exceedingly well focused. Use the 'add files' link next to your send button to get the photo to me.

.

Phone call offers:

If you wish to accept the companies $25 phone call offer, if indeed they send you one, this will go a *lot faster, but it IS 100% optional... or we can continue here in this dialog box at no additional charge.

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Customer reply replied 2 months ago
Thanks Phil. Do you have access to the photos I sent the previous guy?
Here is a list of the load items.
Also, I want to make sure I'm asking the right question so let me see if I can clarify.
I would LIKE to bring one cable (30Amp/240) into the panel and distribute from there. I suspect that's not possible so I'm looking for recommendations - 2- 30Amp runs? Another method to bring more power?
Customer reply replied 2 months ago
Everything is 120. No 240 appliances

Thanks. the water heater and hair drier will not run 24/7 but only 50% of the time, so that allows us to reduce your required wattage from ~11,000 watts to 7 or 8,000 watts this will require a 1500 watt generator,

Watts = volts x amps.... so that we can solve for amps this way given 24 amps (usable) on 230v

24x230 = 5,520 watts, or not enough to run your load, so you will need a 50 amp 230v two pole breaker and wiring to support your load when plugged into shore power.

Each leg of the 230 v will provide 115vac when using the neutral wire.

.

Important note about RATING my work:

I am a retired mechanical engineer and HVAC/electrical/ refrigeration and boiler contractor... with 56 years in this business. The last 20 of those years consulting for major firms nationally..

.

All I ask is please respect me and my input by selecting the***RATING LINK***at the top of your page, that is the only way I am credited through the site.Rating does not affect your charges nor ability to refund if not satisfied.

.

If you need to be coached through a full diagnosis/repair,and wiring etc. for up to two days, and wish to be trained to use test instruments...... that goes well beyond' Just a simple Answer' of course, and goes beyond what most other experts here offer.....rate my simple answer so far positively.. and I will deliver that training and coaching to you All on the same dime so to speak.

.

Lacking a positive rating I can spend days helping a person at my own expense and loose my shirt,shorts and socks on the deal.

.

Attach a close up photo of the wiring diagram glued to the inside of the blower access door and I will mark it up with troubleshooting instructions then follow up with step by step training and coaching until you have a solution.

.

Photo must be exceedingly well focused. Use the 'add files' link next to your send button to get the photo to me.

.

Phone call offers:

If you wish to accept the companies $25 phone call offer, if indeed they send you one, this will go a *lot faster, but it IS 100% optional... or we can continue here in this dialog box at no additional charge.

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Customer reply replied 2 months ago
Not sure I understand "7 or 8,000 watts this will require a 1500 watt generator"
I have a generator it's a 10,000 watt Honda.
I would like to know how I physically wire from the gen to the panel.
Customer reply replied 2 months ago
Please see the photo of the generator panel I sent previously. Specifically the 30Amp plugs

Hello again, the fact of two 30 amp outlets on that generator does not mean that you have 60 amps of 230v power... to sort out how to wire it I need to see a photo of the wiring diagram that came with the generator.

Regarding connecting to the house (shore) power... let me be very direct. It is possible. It is just not cost effective or practical in most circumstances.... a 'transfer switch' is required, those are made to put generator power to the house, not to put house power into the mobile unit however.

My guess if I understand your situation correctly, is that manually switching power sources will be your best option by a wide margin.

I can write you a book about why if you like, but thats a summary, we can go from there without any time limit what so ever.

Regarding the generator sizing, I posted that earlier, perhaps you needed to scroll the screen up to see it here it is again.

"Always size a generator at twice the listed full load... they will not last at all well if run at their full load rating. Something like a car that will do 125 mph top speed.... it won't last a full day at 125, but it will last 10 years at 60 mph."

In other words if the load is 8,000 watts buy a 15,000 watt generator.

this is a very important concept, often violated, resulting in systems that *work perfectly* but only for a month or so, then the generator fails.... especially if it is a 3500 rpm generator.... most are these days.

For about twice the money you can buy a 1750 rpm generator, those will last longer at full load, but is still recommended to run them at no more than 60% of their full load rating.

.

.

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Hello again, the fact of two 30 amp outlets on that generator does not mean that you have 60 amps of 230v power... to sort out how to wire it I need to see a photo of the wiring diagram that came with the generator.

.

Regarding connecting to the house (shore) power... let me be very direct. It is possible. It is just not cost effective or practical in most circumstances.... a 'transfer switch' is required, those are made to put generator power to the house, not to put house power into the mobile unit however.

.

My guess if I understand your situation correctly, is that manually switching power sources will be your best option by a wide margin.

.

I can write you a book about why if you like, but thats a summary, we can go from there without any time limit what so ever discussing all of your options.

.

Regarding the generator sizing, I posted that earlier, perhaps you needed to scroll the screen up to see it here it is again.

.

"Always size a generator at twice its the calculated load... they will not last at all well if run at their full load rating. Something like a car that will do 125 mph top speed.... it won't last a full day at 125, but it will last 10 years at 60 mph."

.

this is a very important concept, often violated, resulting in systems that *work perfectly* but only for a month or so, then the generator fails.... especially if it is a 3500 rpm generator.... most are these days.

.

For about twice the money you can buy a 1750 rpm generator, those will last longer at full load, but is still recommended to run them at no more than 60% of their full load rating.

.

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Customer reply replied 2 months ago
Phil, I don't think it's clear what I'm trying to do so let me recap.
Firstly, I didn't ask about shore power. That will be the next subject after I figure out getting gen power to the truck.
I am converting an old fedex truck to a mobile barber shop. Most of the time it will be running off of the generator. Shore power is a possibility but may not be practical for most businesses that the truck pulls up to.
The truck will have two barber stations going and therefore two hairdryers, two curling irons, the AC...
so I'm concerned that the 30Amp/240 line off the gen work be enough. Are you indicating that is is enough???
I will try to find the wiring diagram for the gen.

30 amp/240 line power is not enough for your load from that generator. I have attached the math to my earlier responses, maybe you were not able to scroll your screen up to them if you are on a smart phone

.

The 10,000 watt generator you have is not enough to run that 8,000 watt load reliably....

.

your load is ~8,000 watts when we consider diversity.... it would run your generator at 80% of its maximum capacity.... and that will burn your generator out within a month or two.

.

The manufacturers misrepresent the generators capabilities, then cover themselves by calling the rating a PEAK rating, or emergency stand by rating (temporary loads)

.

You need a 15,000 watt generator for that load if you want any sort of decent reliability. (I am telling you this after 56 years in the business)

.... and in some cases will warn you not run more than 60% of that max rating for more than half an hour at a time.

------------------

30 amps/240v is not enough to run your load from the generator reliably. I have attached the math to my earlier responses, maybe you were not able to scroll your screen up to them if you are on a smart phone

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Customer reply replied 2 months ago
Gotcha! I understand. Realistically, the blow dryers will each run for a max of 15 minutes per hour so that should cut down on the draw required dramatically. The AC will likely run while the blow dryers are running.
I believe I was incorrect about the 2- 30Amp/240 plugs. The is one 30Amp and one 50Amp. Can you comment knowing this info now?
Sending a photo...

You cannot total up all of the plug in options on the generator to get its total capability.

Its peak capability is 10,000 watts is what determines its net capability, regardless the number of outlets it has.

.

so that you can run 7200 watts from one of the 30 amp rated outlets, theoretically, however these items are not listed to be run at more than 80% of their rating,

so that one 30 amp/240v outlet should not run more than 6,000 watts by itself

then the other outlet regardless of its rating, 30 amps or 50 amps (which I do not see in the photo) should not be run more than 6,000 watts either.... but that would 12,000 watts, way more than the generator is rated for.

You should only run 6,000 watts on a full load basis on that generator.

If you run only one hair drier at a time, and run the AC only after the hair driers go off,.... you could easily get by with the 10,000 watt generator that you currently have.

If you run them simultaneously though any significant portion of the time you will burn out your generator.

.

If this is a chinese made generator cut that 10,000 watt rating down ever further, if its japanese, honda etc. the figures above apply

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Customer reply replied 2 months ago
Firstly I'm not asking you to size the generator so let's stop talking about that.
Secondly, I have not asked to use multiple of the generator outlets.
The plug on the left in the photo is a 50Amp/240V plug which gives me (approx) 10.000 watts. Is this correct?
So I should be able to use this plug, to power everything, correct?

Yes the 50 amp outlet will give you 10,000 watts... I did not see it marked 50 amp though.

.yes you should be able to use the 50 amp outlet for everything.

Phil
Phil, Mechanical Engineer
Category: Electrical
Satisfied Customers: 8,824
Experience: Retired electrical contractor, 51 years experience.
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Customer reply replied 2 months ago
Very good sir. I appreciate you helping me work thru this. If I had seen that it was a 59Amp plug to begin with I may not have had such issues with this.
I also understand your concern about the generator but this particular generator has already been purchased and that's what we'll be using. During a haircut, the blow dryer will be used briefly so the AC and some clipper along with LES lighting will be the main draw, equaling probably less than 4000 watts, briefly reaching 7000 watts when both blow dryers are going. So I think we'll be ok. We'll keep a sharp eye on the generator because of the concerns you voiced.
Thanks!!!
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Phil
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