Thread: branch circuit in detached shop

I'm pretty sure this violates the Canadian Electrical Code, but I have yet to confirm with an expert.

The detached shop built in 1998 is about 30 feet from the house and has one 4 wire feed from a 15 amp double breaker in the service panel. The supply cable goes underground to a junction box just inside the shop and then to a 1500 Watt baseboard heater. From the J-box, they have tapped one of the hots to supply lights and receptacles with 120 volts.
We are allowed to have one branch circuit in a detached building, but I believe this building has two circuits, and therefore a breaker panel should have been installed.

What does your NEC say about this setup?

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Originally Posted by John Kogel

I'm pretty sure this violates the Canadian Electrical Code, but I have yet to confirm with an expert.

The detached shop built in 1998 is about 30 feet from the house and has one 4 wire feed from a 15 amp double breaker in the service panel. The supply cable goes underground to a junction box just inside the shop and then to a 1500 Watt baseboard heater. From the J-box, they have tapped one of the hots to supply lights and receptacles with 120 volts.
We are allowed to have one branch circuit in a detached building, but I believe this building has two circuits, and therefore a breaker panel should have been installed.

What does your NEC say about this setup?

The NEC would say that this is OK since in this instance the 4 wire circuit is a MWBC and for purposes of feeding another structure this would be considered one circuit. The circuit would still require a disconnecting means at the point where they entered the structure. Since it's considered one circuit a grounding electrode system (GES) is not required.

II. More Than One Building or Other Structure
225.30 Number of Supplies.
Where more than one building or other structure is on the same property and under single management, each additional building or other structure that is served by a branch circuit or feeder on the load side of the service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.

225.31 Disconnecting Means.
Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

Originally Posted by John Kogel

I'm pretty sure this violates the Canadian Electrical Code, but I have yet to confirm with an expert.

The detached shop built in 1998 is about 30 feet from the house and has one 4 wire feed from a 15 amp double breaker in the service panel. The supply cable goes underground to a junction box just inside the shop and then to a 1500 Watt baseboard heater. From the J-box, they have tapped one of the hots to supply lights and receptacles with 120 volts.
We are allowed to have one branch circuit in a detached building, but I believe this building has two circuits, and therefore a breaker panel should have been installed.

What does your NEC say about this setup?

John,

I believe the electric baseboard heater should be on a dedicated 20-amp circuit, so a 15 amp breaker is probably using 14 gauge wire and therefore the conductor is undersized; and the circuit, being tapped, is no longer dedicated.

Hope this helps,

Christian

Originally Posted by Christian Mettel

John,

I believe the electric baseboard heater should be on a dedicated 20-amp circuit, so a 15 amp breaker is probably using 14 gauge wire and therefore the conductor is undersized; and the circuit, being tapped, is no longer dedicated.

Hope this helps,

Christian

At least in my end of the country, Ont. may be different, 15 amp is allowed for a baseboard heater circuit, providing the total wattage of the load does not exceed 2880 watts. In fact, the new CEC rule allows for a 20 amp breaker on a 14# copper cable. Electric heat is a fixed load, so the smaller gauge wire is allowed. In this case, the breaker is 15 amp, 240 volt, no problem with that.

I am questioning the addition of a tap for 120 volt lights and outlets. That, I believe, is a violation.

Originally Posted by Christian Mettel

John,

I believe the electric baseboard heater should be on a dedicated 20-amp circuit, so a 15 amp breaker is probably using 14 gauge wire and therefore the conductor is undersized; and the circuit, being tapped, is no longer dedicated.

Hope this helps,

Christian

We do not know what the voltage of the 1500 watt heater is. 120 or 240 ? makes a big difference when determining the electrical load. 1500 @ 120 volt is 12.5 amp
1500 @ 240 volt is 6.25 amps. add in 125% for continuous load and the 1500 @ 240 is 7.81 amps

Originally Posted by ken horak

We do not know what the voltage of the 1500 watt heater is. 120 or 240 ? makes a big difference when determining the electrical load. 1500 @ 120 volt is 12.5 amp
1500 @ 240 volt is 6.25 amps. add in 125% for continuous load and the 1500 @ 240 is 7.81 amps

Thanks, Ken. I didn't open the Junction box to see. I ass-umed 240 to the heater, because it looks like a 240 volt type.
The tie-bar on the breaker prevents operating one leg only.

Is there a rule that prohibits tapping 120 volts off of a 240 volt branch heating circuit?

Originally Posted by John Kogel

Thanks, Ken. I didn't open the Junction box to see. I ass-umed 240 to the heater, because it looks like a 240 volt type.
The tie-bar on the breaker prevents operating one leg only.

Is there a rule that prohibits tapping 120 volts off of a 240 volt branch heating circuit?

John, did you take a look at what posted in post #6?