Electronics > Projects, Designs, and Technical Stuff
How safe is it to use a SSR to control power to a spa? Or use a relay?
DougSpindler:
I would like to know how safe and if it would be a good idea to use a SSR to control the power to a spa/hot tub. We are on a Time of Use rate plan with our power company. My plan is to use a TPLink smart-plug to provide the timing. This give me control of a 120 vac circuit. The TP Link would then be used to control a high current SSR to control power to the spa. The SSR would be used to control the mains to the spa. (Placed after the GFCI in the mains power to the SPA.) I'm wondering if this is a good ideas? I read SSRs do not interrupt the circuit like a relay would. The circuit is energized at full voltage be the current is what's being controlled. I'm wondering if an SSR is a good idea? Is it safe? Would it damage and of the electronics or motors?
Or should I just purchase a high current relay?
bob91343:
Before you spend too much time on this, realize that there are concerns regarding insurance, and that any installation working from the power line must have a permit covering its safety.
You may design a perfectly working system but if an insurance claim is made, the company will be ready to deny the claim based on not having a permit.
DougSpindler:
What concerns should I have about insurance claims? Who would be making the insurance claim?
I live in California and a permit is not required for this type of work.
DougSpindler:
Oh just did the calculation based on our power company's current rates. Using the hot tub during peak hours the cost for electricity is $0.54. Manufacture claims 1,875 kWhr are used per month. Cost to power the hot tub over a year would be $1,275.
If limited to off peak it would be $225. Installing an SSR would save me over $1,000 per year. Well worth it.
Gyro:
It tends to be easier to obtain UL approved high current mechanical relays with decent insulation and contact ratings than SSRs. You'll probably have more choice.
An SSR will have a higher thermal dissipation than a relay too.
EDIT: For something high power like a hot-tub, you're probably looking at a 'contactor' rather than a relay too.
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