Shed Wiring

RalphPeters

I'd like to be able to use a 230V welder at my shed and would like some advise.
The existing power to my shed was run as follows: Main Service Panel is 125 amps, 40 amp breaker feeds a 8 circuit sub panel next to main panel, 15 amp 2 pole breaker brings 240 v to shed through buried Teck90 cable with 3 conductor 8 gauge wire. Into junction box , 1 leg feeds two outlets, the other leg powers two light fixtures. So only 120 volt circuits are currently being used.

The welder I want to use requires either a 25 amp time delay breaker or fuse or 30 amp standard fuse (manual doesn't mention using a 30 amp breaker only fuse)

So to make this work could I change the sub panel breaker size to 40 amp and install a new sub panel in the shed with two 15 amp single pole breakers for the outlets and lights, and a 25 amp time delay dual pole breaker(if available) for the welder? Or would I be better to go from the new subpanel to a 25 amp fused disconnect box?

Scuba_Dave

What is the distance to the shed ?
Not familiar w/Teck 90 cable

AllanJ

The circuits already in the shed must be protected by 15 amp breakers for 14 gauge wires and at most 20 amp breakers for lights and receptacles. So if the feed to the shed is the 8 gauge cable, then you must install a subpanel or sub-subpanel there to go with a 40 amp breaker back at the main panel or first subpanel.

I would go as you described and with the 25 amp breaker set in the new subpanel.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

J. V.

Search "Sub Panels" at the top of this page and you can read about your application for weeks.

RalphPeters

Length of cable running to shed is 30 feet.

Must be a canadian thing:

Application:
Teck 90 cables are used in the pulp and paper, mining, petroleum, and chemical industries, as well as, in commercial and industrial building applications. They may be used under the following conditions:

• In ventilated, non-ventilated, or ladder-type cable trays in dry or wet location
• exposed or concealed wiring in dry or wet locations
• on walls or beams
• directly buried
• CEC Class 1 Div 1&2 Group A,B,C,D
• -40°C (-40°F) dry or wet environments

Cable running to the outlets and lights are 14 gauge wires so yes, the plan would be to connect these to the new sub panel with either two 15 or one 20 amp breaker and a 25 amp for the welder.
Is a 40 amp breaker feeding this new subpanel sound right?

Attached Images

 

AllanJ

A 40 amp breaker is the maximum for 8 gauge wires.

__________________
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

brric

40 amps is only the maximum ampacity for # 8 conductors in NM cable. Other applications and conductor types allow up to 55 amps.