jac911

I've used the forum before for help in off topic questions and now need help with another issue.

Does anyone on the list have experience with home wiring? Installing a heater in my garage and I have some questions. The installation manual says the the unit uses 31.3 amps. It says to use 8 ga wire and a 50 amp breaker.

My questions are: Can I use a dryer plug cable rated for 30 amps and a hard wired socket also rated at 30 amps? Will a 40 amp breaker suffice or do I need the 50 amp that they call for? If anyone can help with the answers please PM me to not clog up the list.

Thanks in advance for any help.

JC 96 TT

jay@EZimmoblock.com

The difference between 30 and 31 amps is so small and the ratings are so conservative that you should be fine with the 30 amp hardware. The only time I'd go higher on the cable is if the the cable is really long, but that's a voltage drop issue (less power to the load), not a safety issue. As for the breaker, 40 amps probably ok in a situation where you only have the one known device on the circuit (the heater) and no possibility of adding other loads to the circuit.

71-3.0-911

Probably advised 50a since the next most common option is 30a. I always like to underload a circuit vs tap dance on the edge.

pp000830

Hi JC,
I am not a professional electrician, however here are my thoughts.
For safety, I would use a plug and socket rated equal to or above the device's peak demand amperage, in this case, 50 amps.
The reason one should not use a lower one is the heater may draw more current at startup than its rated wattage and a lower-rated socket and plug may experience higher heat cycling temperatures. If a smaller breaker is used you may experience tripping issues.
If a larger breaker than the specified one is used the breaker offers less protection to the circuit and the appliance.
The gauge wire has to do with wire heating and voltage drops, 8 gauge is probably a minimum. If the electrical run is longer even a lower gauge can be considered. There are tables in electrician's manuals available online that specify voltage drops to be expected at a given gauge over specific distances. Also, use copper wire and terminations made for copper. At one time aluminium wire was used in homes and needs to be used with devices (sockets) that are aluminum conductor compatible.
Keep in mind that any electrical wires and devices added to your home will be there for the life of the home and so safety and reliability is king, not saving a few bucks.
Andy

fatmike

Why wouldn’t you just follow the manufacturers recommendation?

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Twilightblue28A

Follow the manufacturer's instructions.

Foxman

IainM

Whatever you do, don’t install a breaker larger that the wiring capacity. That’s how fires start. The breaker is to protect the downstream wiring.

Jeff96-993

If you want an expensive court case with your insurance company, then I'd suggest you do whatever you want. When/if your house burns down, then it's on you. The insurance company instantly wins, when they see you didn't follow both the local building code AND the manufacturer's recommendations.

Your solution is just like riding a bicycle on the street... if anything goes wrong, regardless of who's at fault or what the fault is, you're dead. You lose no matter what. Don't do it to yourself.

With that being said.... building codes are getting ridiculous... who's writing these things?????

jac911

If you want an expensive court case with your insurance company, then I'd suggest you do whatever you want. When/if your house burns down, then it's on you. The insurance company instantly wins, when they see you didn't follow both the local building code AND the manufacturer's recommendations.

Thanks for the input and I agree. I have some experience with house wiring as I've wired multiple 110v circuits. This is the first 220v circuit and I have been scrupulously following the heater manufacturers instructions. I spoken to multiple folks at different electrical supply houses. Each person I spoke with corroborated statements from the others. All the materials are the size and type recommended by the manufacturer and all the connectors are up to the job per the supply house guys.

That being said, I may not be an electrician, but I ain't stupid either. I would never turn it on an forget it. The plan is to get the heater running and monitor heat levels in the connections with my infrared thermometer. Any high draw that doesn't trip the 50 amp breaker required by heater manufacturer will surely show up in high temps in the connections. If that occurs then it's shut it off.

Thanks for your input and your concern is appreciated.

JC 96 TT

PZB993

When sizing the conductors for your electrical space heater you need to consider it a "continuous load". This means you need to multiply the FLA by 125%. This is the reason for the larger wire. Please don't take the advice of running it off your dryer circuit.