Upgrading my electrical feeds and controls

[storeman]

After a lot of delays, I am about to tackle Peter's auto-start boards. I bought one for each generator. Am putting together a generator selector switch to ensure both units can't conflict should someone start both at one time.

I'm currently feeding my panels off 100' of 8/4. (I know that is too light but have never loaded the 002a over 75% in a lights out situation.) Most of my essential stuff is propane.

Haven't run the 003a as backup yet and don't intend to until upgrade is completed.

My intention is to go 6/4. Currently the 8/4 is above ground in 1.5" pvc conduit. Home depot has #6 stranded easy pull pre-lubricated THHN available for 42 cents a foot, about $160 to replace my 8/4. I would pull the 8/4 and fish the #6 wires through the 1.5" conduit.

My questions are:

1. Would I be better off using SOOW at 2-3 times the cost? If so, why? (I really don't want to bury the cable.)

2. If SOOW is the right approach, can I put it in the exposed 1.5" PVC conduit running down the side of the house?

I'll post pics as I sort out the control panel for the 2 generators using Peter's auto-starts and the associated relays and generator selector switch.

Thanks for your thoughts. Jerry

 

[dependable]

Soow is the right wire if you are running temp setups above ground. It is tough, flexible and therefore expensive. If I were doing a permanent set up, I would use(and bury) 2'' conduit with equivalent of 6/4. No need for SOOW in that application, as you don't need to flex it and insulation is protected by conduit.

I keep my gensets in container and get out with machine to deploy, so I use 6/4 SOOW.

Even with lighter loads, it would be better to use thicker wire on longer runs. 100 ft is probably as long as I would consider with 8/4 and 002.

 

[Jimc]

yeah mine is a 15ft soow feeder fom the gen to a power inlet box. from there its 4-6ga thhn in conduit to my panel. only the soow is used in exposed areas.

 

[storeman]

My conduit is strapped to the house about 3' off the ground. Seems like thhn would be okay in that environment. Leads from generators to the controls will be soow in the shed.
Jerry

 

[coxju04]

Has anyone every used Aluminum wire to hook up their MEP-Generator?

 

[Harleyd315]

I think THHN would be the choice for conduit runs. According to my electrician friend, SOOW cable is not supposed to be in conduit as it needs to be exposed to the air for cooling. Maybe check with some electricians in your area codes may be different in your neck of the woods.

 

[Isaac-1]

Aluminum wire should not be used in high vibration environments due to breakage issues.

Ike

 

[n1oty]

SOOW in conduit would be a code violation in most areas. It is meant to be exposed to the air for cooling. THHN generally carries a higher temperature rating than SOOW, so it has the added benefit of supporting more amperage than typical SOOW for a given conductor size. For example, most THHN is temperature rated in the NEC table for 90 Centigrade, where typical SO derivatives are rated 60 C. #6 AWG 60 C conductors have a maximum table ampacity of 55 amps before applying any de-rating factors. #6 90 C conductors have a maximum table ampacity of 75 amps before de-rating factors. So, THHN can safely carry some addition amperage, assuming the conduit is sized to allow for appropriate conductor cooling.

John

 

[storeman]

N1OTY,
Is 1.5" conduit adequate for #6 THHN 4 wires?
Jerry

 

[Jimc]

jerry i think i ran 4 #6 thhn in 1 1/4". it worked and was a bit of a bear to get it through but i did get it. 1.5" would certainly be better and easier

 

[storeman]

Thanks Jim. I thought it was okay.
Jerry

 

[n1oty]

N1OTY,
Is 1.5" conduit adequate for #6 THHN 4 wires?
Jerry

Jerry,

I will have to break out my NEC to confirm, but I believe that the maximum conduit fill percentage at this ampacity and driving any inductive loads (think motors) is limited to around 35 percent or so. I'll check the NEC later today.

John

 

[storeman]

Thanks John. I wonder what that translates to.

 

[n1oty]

Tables 4 and 5 of Chapter 9 cover the calculation of conduit fill percentage. I calculated the area of four #6 THHN conductors from Table 5 as being .2028 square inches (.0507 per conductor). Table 4 shows a total area of 1.986 square inches for 1.5 inch schedule 40 PVC and 1.711 square inches for 1.5 inch schedule 80 PVC, the difference because of wall thickness. If you are using schedule 40, your fill percentage with 4 conductors is shade over 10 percent. If you are using schedule 80, your fill percentage is 12 percent. Subtract 15 percent conduit area for each elbow. I would surmise that, even with a few ells, you are very safe with 1.5 inch conduit.

John