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Discussion Starter · #1 ·
I would like to control my pool heater (220v, 50A) using a relay/contactor ( Elk heavy duty relay-contactor; the relay box is not recommended for use in wet places). This would be controlled by 120v from a power cord plugged into a Wemo outlet, allowing ipad scheduling.

My question is where to locate the relay box? I think the options are;
1. in the basement next to the house main breaker box,
2. in the garage on the wall; the heater is located outside.

Is there any regulation or recommendation on location? For a novice, which is the simpler?

Basement: If I install it in the basement I think I would have to mount relay box next to main breaker box. Presumably I would have to run power from the breaker box to the relay box, then back to the breaker box outlet. I would have to connect the two with a single (?) metal conduit. Is this correct? I think I would have to extend the wiring to reach the relay box; can I use wire nuts to do this? Is it OK to have these in the main breaker box?

Garage: This strikes me as more complicated: the 240v power line conduit currently emerges from the ground going to a circuit breaker- also mounted outside. Since the relay box is not recommended for wet places I would have to mount this inside the garage. Therefore, I would have to interrupt the conduit and insert a bend to go through the wall into the garage. After connection to the relay box, I would have to connect another conduit through the wall to connect the wires to the breaker.

Many thanks for your help.
 

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Disconnect the wiring from the breaker panel and route to the relay box mounted close by the panel. Then use a short run of cable or a short conduit nipple with wires to go from the breaker to the line side of the relay. The existing wire now goes to the load side of the relay.
 

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Discussion Starter · #4 ·
Thank you for the info.

Placing the relay box next to the breaker box: I will need to extend the original wires to reach the relay box. Is it OK for me to extend these wires using wire nuts that would be located within the main breaker?
 

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haball said:
Thank you for the info. Placing the relay box next to the breaker box: I will need to extend the original wires to reach the relay box. Is it OK for me to extend these wires using wire nuts that would be located within the main breaker?
No. Locate the relay box in a place where you can run the cable to the heater directly into the relay box. Then terminate those wires to the load side terminals. Purchase a short length of wire from breakers to the line side of the relay.
 

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Discussion Starter · #6 ·
OK, thank you. I'll try that.
With regard to the 120v power plug for the relay box: there's an outlet socket attached to the side of the breaker box. Is it OK to use this socket for the Wemo/power plug?
 

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yes. That is a general purpose socket fine to use for Wemo. Just be sure to wire from the wemo to the relay coil properly. Proper strain relief coming out of relay box, suitable cable, 600V rated, if you use less than 14AWG then you'll need a fuse on hot side to protect the wiring.

If you use ZWave instead of WeMo you can get a nice clean box all in one. good to 30A resistive.

http://store.homeseer.com/store/Int...-AOgS6h2VzaZEZdLi6GKF1aOFlJKOEG86EaAvZW8P8HAQ
 

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No. Locate the relay box in a place where you can run the cable to the heater directly into the relay box. Then terminate those wires to the load side terminals. Purchase a short length of wire from breakers to the line side of the relay.
There's no reason he can't do it the way he proposed, and it may be easier. Unless he's in Canada, it's OK to make connections with wire nuts inside a panel. He could just run a single conduit out of the panel to the contactor, and wire it as a switch loop (two wires plus ground).
 

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Discussion Starter · #11 ·
I check in the breaker box and there's plenty of wire length to reach the relay box.
I note the circuit breaker for the heater is rated 50Amp. Does this mean I'll need 10SWG wire to feed from relay back to breaker box? Sorry if this is a silly question but does color of wire matter? Lastly, what do I need to do with regard to earthing the relay box?
Many thanks.
 

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For 50A, you need #8 or #6 depending on the type of wire and what it's connecting to. The hot wires cannot be white, grey, or green - any other color is OK. All metal parts must be grounded. If you use metal conduit from the panel to the relay box, that conduit will provide the grounding means.
 

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Discussion Starter · #13 ·
OK. I've bought the #6 wire to be on the safe side. I was planning on using a 1/2" box spacer connector (3" long) to connect the wires from the relay box to the breaker. However, I now see that inserting 4 x #6 wires through the connector is quite a tight fit. Is this OK, or do you recommend I use a 3/4" fitting?
 
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