sub panel

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jap2525

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Picture this,

a house panel has a 60a 2p breaker installed.6/3 with ground is extended to an attached garage where there is a 100a mainlug 4 cir panel.
in this subpanel is a 2p 30a for air compressor and (2) 1p 20's for 1 for lights the other for recepts.Customer wants to add another subpanel on the outside of the garage for future 240v rv receptacle,hot tub and outdoor gfi receptacle.He would like to have the breakers for the outside devices in the outdoor subpanel,the items listed are rarely used at the same time.the question is since the indoor subpanel wiring is protected by a 60a 2pole breaker in the house panel,can #6 wiring be extended to the new outdoor subpanel with double barrel lugs installed in the garage subpanel to accomodate this or not? is this considered a tap or just an extension of a 60 amp branch circuit? Thanks in advance.
 
Re: sub panel

I don't think you have to worry about it being a tap since you are using the same size wire. What's wrong with putting the breakers in the same panel anyway?

That aside, I would do some load calcs before assuming that the 60 amp and #6's are adequate. Doesn't matter if customer says everything won't be used at the same time.

-Hal
 
Re: sub panel

The panel in the garage is a 4 circuit and it is full with the 2 1p's and the 1 2p.there would be no need to install a panel inside with more circuit space if the feeder could be extended as stated to the outside subpanel.
 
Re: sub panel

From a design standpoint, I'd want a bigger feeder from the house panel if you're going to be loading it up with all that stuff. Voltage drop could be significant.

The only code thing that struck me was how the 6/3 is protected with a 60A breaker. I'm pretty sure 310.16 limits #6 NM to 55A, and since it will feed receptacles, the round-up rule for breaker sizes doesn't apply. I have 6/3 feeding the subpanel in my own garage, and I have it protected with a 50A breaker.
 
Re: sub panel

I believe this is a feeder instead of a branch circuit since it is feeding the subpanel.My original post may not be worded correctly.
 
Re: sub panel

Originally posted by jeff43222:
the 6/3 is protected with a 60A breaker. I'm pretty sure 310.16 limits #6 NM to 55A, and since it will feed receptacles, the round-up rule for breaker sizes doesn't apply.
Click to expand...
This is not a branch circuit feeding receptacles this is a feeder to a panel, as long as the calculated load is under 55 amps you may use 240.4(B) and round up to the 60 amp breaker. :)
 
Re: sub panel

Iwire,
what do you think about extending this feeder to the new subpanel? yes or no.
 
Re: sub panel

Originally posted by jap2525:
Iwire,
what do you think about extending this feeder to the new subpanel? yes or no.
Click to expand...
Forgetting about the load for a minute I see no violation in extending the feeder to a second panel.

However when we consider the load that they want to run "future 240v rv receptacle, hot tub and outdoor gfi receptacle" IMO the 55 amp feeder will be too small for these loads in addition to the existing "2p 30a for air compressor and (2) 1p 20's for 1 for lights the other for recepts"

RV outlets are 20 to 50 amps 240 volt, Hot tubs can run 50 amps 240 volt, the compressor may be drawing 15 to 25 amps at 240.

The 55 amp feeder is looking kinda small. :p

[ October 05, 2004, 04:11 PM: Message edited by: iwire ]
 
Re: sub panel

I agree with Iwire. This 60 Amp "feeder" is getting too small real fast. I've seen alot of these types of installations, usually by the homeowner. They always ask me "what's wrong" when their "main" 60 Amp breaker keeps tripping.
 
Re: sub panel

All spa prewires we install are 50 amp.The mid to high end units are usually rated at 50 amp.Sounds like a H.O. horror story in the making.Compliant yes but :roll: While online I`ll ask this question,Pool heater data plate has 39.5 min. and max.breaker as 60 .Wire for min and fuse for max. Right # 8NM.
 
Re: sub panel

If I was going to install a 60 amp breaker for the maximum overcurrent protection device,I would rate my wire for 60 amps,but thats just me.
 
Re: sub panel

If I was going to install a 60 amp breaker for the maximum overcurrent protection device,I would rate my wire for 60 amps,but thats just me.
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But this would be a code violation if the cable is type NM, and is certainly not the intent of 240.4(B).


The conductors must be sized to handle the calculated load. If the calculated load does not correspond to a standard sized overcurrent device, section 240.4(B) allows us to use the next higher standard sized one, but it does not allow us to increase the ampacity of the conductors.

[ October 08, 2004, 03:27 AM: Message edited by: itasca_mn ]
 
Re: sub panel

Originally posted by itasca_mn:
If I was going to install a 60 amp breaker for the maximum overcurrent protection device,I would rate my wire for 60 amps,but thats just me.
Click to expand...
But this would be a code violation if the cable is type NM, and is certainly not the intent of 240.4(B).


The conductors must be sized to handle the calculated load. If the calculated load does not correspond to a standard sized overcurrent device, section 240.4(B) allows us to use the next higher standard sized one, but it does not allow us to increase the ampacity of the conductors.
Click to expand...
What are you talking about?
I said if I was going to install a 60amp breaker I would size my wire for 60 amps,,,,,,,,,I didn't say what size that would be.
 
Re: sub panel

Originally posted by jap2525:
If I was going to install a 60 amp breaker for the maximum overcurrent protection device,I would rate my wire for 60 amps,but thats just me.
Click to expand...
So you are saying you run 4 AWG CU for a 60 amp panel?

Overkill IMO unless the run is long.

Table 310.15(B)(6) allows 4 AWG CU for a 100 amp service. :)
 
Re: sub panel

I did'nt say what size wire I would use,or insulation,or installation proceedure. I said I would rate my wire for the 60 amp overcurrent protection device if it were me.
 
Re: sub panel

I understand that you did not specify a size.

The opening post specified NM cable, the only way to use NM cable and have a conductor rating 60 amps or more would be to use a size larger than 6 AWG.

Of course depending on termination temperature ratings you might be able to use 6 AWG MC cable or pipe and have a 65 amp rating.
 
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