Multiple 50A 240V in series (branching 240V circuits)

[dcg9381]

Hi.. I just dropped a 100A panel into a 40'x60' shop building. I'm needing to put 50A outlets (largely for an RV OR Welder - but not both) on 3 interior corners of that building.

I can certainly do this with 3 individual runs of 50A circuits and 3 individual 2-pole breakers. However, this is expensive, and it eats up 75% of the total capacity (per NEC) of the panel itself (a 100A panel is limited to 200A worth of breakers).

Nothing in NEC prohibits having 240V circuits in series that I know about, it's just an unusual configuration. However, the 50A sockets are not designed for chained power, so it gets messy.

What I'm thinking about doing is using splices (3 per box).
This is the splice design that I'm considering. But even these would be expensive at 4 splices per box - about $60 per outlet just to splice them.




Anyone done this before or have a better way to do it?

 

[wyliesdiesels]

Hi.. I just dropped a 100A panel into a 40'x60' shop building. I'm needing to put 50A outlets (largely for an RV OR Welder - but not both) on 3 interior corners of that building.

I can certainly do this with 3 individual runs of 50A circuits and 3 individual 2-pole breakers. However, this is expensive, and it eats up 75% of the total capacity (per NEC) of the panel itself (a 100A panel is limited to 200A worth of breakers).

Nothing in NEC prohibits having 240V circuits in series that I know about, it's just an unusual configuration. However, the 50A sockets are not designed for chained power, so it gets messy.

What I'm thinking about doing is using splices (3 per box).
This is the splice design that I'm considering. But even these would be expensive at 4 splices per box - about $60 per outlet just to splice them.




Anyone done this before or have a better way to do it?

What code is telling you that youre limited to 200a in breaker ratings in a 100a panel?

(Hint: there is no code) the panel can have way more than that because its all about the connected load not the breaker ratings.

Also, the 50a outlets would be in parallel not series..

 

[sberry]

How many panel spaces do you have and what brand? Are you going all one way or different directions. What type of welding machines and what wiring method, cable or pipe.
One of my 200's prolly has a thousand amps connected breakers considering there is about 10 50 and 60 in it and even another 100 to the feed thru lugs.

 

[pattenp]

It all depends if you are subject to electrical inspections and if this is on a residential use property. IRC (International Residential Code), which is adopted by Texas, limit circuit size to 20A when having multiple receptacles on the circuit. See E3702.5

 

[nsula_country]

I did this exact thing in our shop. Three 50A receptacles on one 50A breaker, all #6 stranded with #10 stranded ground. Two of these are 4 wire, one 3 wire. Used for RV and welder.

Those Polaris style connectors are IMHO the easiest, fastest way, but not the cheapest. I had a hand full of split bolts, roll of 130C and some extra 4 11/16" boxes... So I split and spliced old school. Tighten split bolts. Wrap in Teflon tape. Wrap with 130C. Wrap with 33. Repeat till done. Install box cover.

CT

 

[dcg9381]

What code is telling you that youre limited to 200a in breaker ratings in a 100a panel?

The one that says you can't exceed the design limits of the panel.

No, you're right - it's not technically a code issue, there is no NEC rule that determines the ratio of max breaker amps to service feed amps. I stand corrected on that. That being said, it IS a minor concern in my circumstance as I've got a dual-fed subpanel (solar and service entrance). The panel itself will have a limit internally.

Regardless, I'd prefer not to eat 3 x 2-pole breaker spaces - unless absolutely necessary.

It all depends if you are subject to electrical inspections and if this is on a residential use property. IRC (International Residential Code), which is adopted by Texas, limit circuit size to 20A when having multiple receptacles on the circuit. See E3702.5

Thank you for this.
You're citing:

E3702.5 Branch Circuits Serving Multiple Loads or Outlets

General-purpose branch circuits shall supply lighting outlets, appliances, equipment or receptacle outlets, and combinations of such. Multioutlet branch circuits serving lighting or receptacles shall be limited to a maximum branch-circuit rating of 20 amperes. [210.23(A), (B), and (C)]

• I'm not subject to any inspection other than a potential inspection upon resale.
• The building is non-residential. However it may be, at some time in the future, partially framed in for residential, which sounds like it might trigger IRC.

> Also, the 50a outlets would be in parallel not series..[/QUOTE]
This is electrically correct.. I should have said "on the same circuit".



With what those connectors cost - it may be a lot less expensive to do the separate breakers, it just results in a lot more wire in the walls than necessary. I'm not willing to do split bolts and tape - although it could be argued that they're the same thing...

 

[Jim greengo]

What code is telling you that youre limited to 200a in breaker ratings in a 100a panel?

(Hint: there is no code) the panel can have way more than that because its all about the connected load not the breaker ratings.

Also, the 50a outlets would be in parallel not series..

 

[75gmck25]

Don't make it overly complicated to save a small amount of money.

Just shop for a good price on 6/3 copper wiring and run 3 different 50 amp circuits that cover each location. 100 amp panels with more breaker positions are not much more expensive than small panels, and 240 volt 50 amp breakers are also relatively cheap. If you do it right the first time you won't have to worry about code compliance down the line.

Bruce

 

[dcg9381]

Don't make it overly complicated to save a small amount of money.
Bruce

It looks like it's more expensive (perhaps) to do these on the same circuit. I believe that it's simpler that way - fewer breakers, less wire, etc. The splices, 3 needed per outlet, are the killer.. But simple is probably subjective.

 

[mike93lx]

Don't make it overly complicated to save a small amount of money.

Just shop for a good price on 6/3 copper wiring and run 3 different 50 amp circuits that cover each location. 100 amp panels with more breaker positions are not much more expensive than small panels, and 240 volt 50 amp breakers are also relatively cheap. If you do it right the first time you won't have to worry about code compliance down the line.

Bruce

Or if you don't hate money, get aluminum wire

 

[u2slow]

Does your welder actually need 50Amps? Mine only needs a 20A/240V circuit. (#12 wire ) Also needs to be quite a large RV before you need more than 30A/120V. (#10 wire)

Maybe consider running conduit to a box at the three locations, and only populate each with wire and receptacle when you're closer to using it?

 

[theoldwizard1]

Does your welder actually need 50Amps? Mine only needs a 20A/240V circuit. (#12 wire ) Also needs to be quite a large RV before you need more than 30A/120V. (#10 wire)

Some GIANT sized RVs are wired for 240V/50A !

Maybe consider running conduit to a box at the three locations, and only populate each with wire and receptacle when you're closer to using it?

If you can "daisy chain" the conduit from box to box, this is a MUCH simpler solution !

Aluminum XHHW is cheaper than copper THHN even when you step up a couple of gauges. Need larger conduit.

 

[nsula_country]

Does your welder actually need 50Amps? Mine only needs a 20A/240V circuit. (#12 wire ) Also needs to be quite a large RV before you need more than 30A/120V. (#10 wire)

Maybe consider running conduit to a box at the three locations, and only populate each with wire and receptacle when you're closer to using it?

For a Harbor Frieght welder and a popup camper this is fine...

We don't know what the OP has for loads other than the size plugs on the cords. They seem to have 50A 3P/4P males.

We have an RV and a welder that can stretch out a 50A circuit. With a 30A/50A combiner, 2 ACs will trip a 30A, 1P. Hence why I personally ran 50A, #6cu.

CT

 

[u2slow]

For a Harbor Frieght welder and a popup camper this is fine...

We don't know what the OP has for loads other than the size plugs on the cords. They seem to have 50A 3P/4P males.

^ Exactly.

Most 240V welders use a 50A plug regardless of the draw. My Milermatic 211 is happy on a 20A circuit. I've also made up a #12 extension cord for it. Best to check the welder's specs for what it requires.

If the OP does only 'need' 30A/120V for his RV (i.e. most RVs up to 30') then smaller circuits could save some cash.