Sub panel questions

[quickfarms]

I want to add a sub panel in my yard halfway between my main panel and the shop sub panel

The goal is to add a 50 amp RV power box for now and eventually convert it to a sub panel for a future building

My research has lead me to believe that the electrical code has changed since I built the existing shop 18 years ago

When the existing sub panel was installed we ran two empty 3/4” pvc conduits in the trench

Based on the old code I could pull 3 #8 thhn wires and use a ground rod like the sub panel.

Now I think I need to also pull a ground, is this correct?

If I add a third conductor to the conduit I would need to pull #6 for 50 amps or use a 40 amp breaker due to the 80% derating

First question is does the ground need to be the same size or can I use a #10 wire?

Can you actually pull this through the 3/4” pvc conduit?

What is the best way to hook up the wire to the fish tape for pulling?

Do I still need to install a ground rod?

 

[wyliesdiesels]

I want to add a subpanel in my yard halfway between my main panel and the shop subpanel

The goal is to add a 50 amp RV power box for now and eventually convert it to a sub panel for a future building

My research has lead me to believe that the electrical code has changed since I built the existing shop 18 years ago

When the existing sub panel was installed we ran two empty 3/4” pvc conduits in the trench

Based on the old code I could pull 3 #8 thhn wires and use a ground rod like the sub panel.

Now I think I need to also pull a ground, is this correct?

So you want to tap into the feeder running to the shop, to feed the RV pedestal?

Hopefully the wire you ran is THWN. THHN is dry location only.... most THHN is dual rated however...

the answer to your ground wire question can be found in the electrical FAQ sticky.

But yes, you need a 4-wire feeder with an isolated neutral bar in the subpanel, in addition to 2 ground rods.

However, for this i would run a separate feeder to the RV pedestal....

If I add a third conductor to the conduit I would need to pull #6 for 50 amps or use a 40 amp breaker due to the 80% derating

First question is does the ground need to be the same size or can I use a #10 wire?

Can you actually pull this through the 3/4” pvc conduit?

What is the best way to hook up the wire to the fish tape for pulling?

Do I still need to install a ground rod?

#10 is good for up to a 60a breaker per table 250.122

yes you could fit 3 #8 and a #10 in the conduit, however pulling a #10 in after the fact may be a bare, depending on how long it is.

I would run a separate feeder to the RV pedestal.

and yes you need TWO ground rods not just one.

 

[Bert_]

No derating. You will only have two current carrying conductors. The ground obviously does not normally carry current and you do not count a neutral when it only carries the imbalance.

 

[quickfarms]

Next question

Is it still acceptable to use black wire and tape the correct color on the ends in the panels?

 

[Terry D]

Next question

Is it still acceptable to use black wire and tape the correct color on the ends in the panels?

#4 and larger

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[quickfarms]

#4 and larger

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When did that change?

 

[Terry D]

When did that change?

Not sure, its been that way for a long time. This only applies to the grounded and grounding conductor

The grounded conductor #6 or smaller must have a continuous white or gray outer finish its entire length.

The grounded conductor #4 and larger can be identified with white or gray tape at its terminations

The grounding conductor #6 and smaller must have a continuous outer finish green or green with yellow stripe(s).

The grounding conductor #4 and larger may be identified with green tape at each end and every point it is accessible. Conduit bodies that doesn't contain splices are exempt.

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[dcg9381]

In 3/4" conduit, I'm able to pull 6 ga / 4 conductor wire (just barely) that has a jacket on it. I believe it's rated for 60A. It can be done with decent lube and if you can push/pull, maybe one 90 turn. With a de-rated ground / individual cables, you'd be less tight.

The reality is, however, that "50A" RVs run fine on a 30A @ 240V connection... Yes, both ACs. An RV 50A pedestal provides ~4x the power of a 30A pedestal (240v vs 120v). Just protect with the correct breaker. 8 ga wire (40a?) would power pretty much rational "normal" RV, meaning most RVs with less than 3 ACs.


For RV pedestals I buy these Siemens Talon outdoor rated sub-panels. You can get them on Amazon.

They look like this (below), cost <$150. They come with 50A RV outlet (240v), 30A RV outlet (120v) and a 20A GFCI outlet and all breakers. 4 spare slots for additional stuff. I literally have 4 of these things outside my shop for configurations that support buddy's RVs...

 

[Bert_]

In 3/4" conduit, I'm able to pull 6 ga / 4 conductor wire (just barely) that has a jacket on it. I believe it's rated for 60A. It can be done with decent lube and if you can push/pull, maybe one 90 turn. With a de-rated ground / individual cables, you'd be less tight.

Hopefully you aren't talking about Romex. Romex cannot be ran outside or underground. Putting it in conduit does not change that.

 

[wyliesdiesels]

In 3/4" conduit, I'm able to pull 6 ga / 4 conductor wire (just barely) that has a jacket on it. I believe it's rated for 60A. It can be done with decent lube and if you can push/pull, maybe one 90 turn. With a de-rated ground / individual cables, you'd be less tight.

The reality is, however, that "50A" RVs run fine on a 30A @ 240V connection... Yes, both ACs. An RV 50A pedestal provides ~4x the power of a 30A pedestal (240v vs 120v). Just protect with the correct breaker. 8 ga wire (40a?) would power pretty much rational "normal" RV, meaning most RVs with less than 3 ACs.


For RV pedestals I buy these Siemens Talon outdoor rated sub-panels. You can get them on Amazon.

They look like this (below), cost <$150. They come with 50A RV outlet (240v), 30A RV outlet (120v) and a 20A GFCI outlet and all breakers. 4 spare slots for additional stuff. I literally have 4 of these things outside my shop for configurations that support buddy's RVs...

#8 THWN is good for 50a NOT 40a.

were you referring to NM-b or UF-b, which has a 40a ampacity?