Hi, I have been trying to figure out the part number to replace the broken CR4395 in my snowmelt control box. The box includes the controller, contactors, and GFCI for the heating elements (sidewalk snow melter). The GFCI is actually a CR4395. I have been able to figure out all the details/code for the CR4395, except the Trip Status type (figure below). For this application (heating element -snow melt mat) what type of Trip Status should be used? The manufacturer website (CR4395) shows four types EH, EL, LH, and LL? I greatly appreciate your help to figure out which of the four types should I choose.
here is a photo of the CR4396 part in the box
I can not be absolutely certain on my reasoning out the likely choice, so your best bet is to ask the manufacturer of the system, if you haven’t already.
For the latching vs. non-latching part it’s pretty easy to determine from usage, or the operating instructions.
- If it’s a latching device then you will need to either manually use a switch or, disconnect power wires from the system, to reset it after a fault is corrected.
- If it’s a non-latching part it will require no user intervention after a fault is corrected.
For the high vs. low sensing, the most likely choice would be a high trip point like standard household circuit breakers.
Hello PaulHunch, Thanks for the reply. I am not an expert and just trying to order the right part to replace it with the current one. Therefore, I am going to repeat what I learned from your reply to make sure that I do not misunderstand the issue. The GFCI is monitoring the flow of current for the contractors’ wire. The controller automatically connects and disconnect the contactors over time and sometimes several times in a day. Therefore, I assume the contractors do not latch. Does it make sense? I greatly appreciate your help
The part numbers for the relay and external current transformer should be indicated on the labels applied to each. This information appears to have been removed from the image on the CR magnetics page shown above, but can be seen in the images for these products.. Removing the device should allow you to view the label and identify the proper replacement.
That said, how did the conclusion that the device in current use is faulty come about?
Unfortunately I believe the answer is no.
My guess about the operation of this device is that the device normally operates turning the heating elements on and off automatically driven by the large green module in your photo.
I believe the current sensing relay with GFCI is a safety device, so it does not operate at all under normal conditions. It will only activate when there is a fault in the system just like a regular circuit breaker in your home.
It’s possible that there is nothing wrong with the system and it has simply tripped due to a temporary fault and you need to disconnect power (flip the regular circuit breaker that feeds the system off and then on) to reset the device.
If you can provide any of the following information I can refine my guesses.
- Model name/number
- Installation manual
- Operation manual
Hi Paul. I have attached a copy of the technical specs for the control box. You are correct in your understanding of the system with a couple of exceptions. The green box is just the power supply that converts 120 VAC to 24 VAC. The controller is not shown in the photo because it is on the cover door of the box. The controller activates or deactivates the four contactors (black boxes in the photo). The GFCI is a safety device that monitors the current going through the wires of the contactors. I think your initial assessment that it is high sensing (vs. low sensing) is correct. I have also attached the spec for the controller. The box has the test and rest bottom for the GFCI which is connected to the controller. Thanks for your input and help.
PYROCON19 SPECS.pdf (629.9 KB)
PYROBOX3-19 DATA SHEET.pdf (697.4 KB)
Additional documents from the two manufacturers web sites:
CR4395 Relay Box Sheet
Major Caveats You Need To Be Aware Of
- There is nothing in the documentation to completely resolve the question and getting it wrong can lead to loss of life and property.
- Depending on local laws, it may be illegal to service this device without a master electricians license.
- Depending on local laws and your policy terms, a DIY repair on this unit may void your homeowners insurance.
My recommendations on how I’d proceed:
- Call the company that installed it and ask for a quote, if $1000.00 US or less I’d pay them for the peace of mind of having the installer assume the legal liability.
The rest of these are 100% at your own risk, following these actions may lead to, or directly cause, loss of life and/or property and it will be 100% your liability.
- The Relay Box Sheet clearly shows the part information label on the side that is hidden by the PYROBOX wires. Looking for that as @rick_1976 suggested above is your best bet.
- If the label has been removed by Meitav-tec, contact them and ask for the part number. Meitav-tec - Support
- Replace the part with the latching high current sensing relay.
Hi Paul. Thanks for the reply and your warnings are correct and fully noted. I have a licenced electrician and he is of the opinion that to bypass the GFCI in the box and install GFCI breaker in the panel for the power feed to the box/heater mats. His solution makes sense to me and it costs almost the same. However, I am not knowledgeable enough to be sure whether his solution is as good as the original box configuration. I was hoping to restore the box to its original condition. The other question in my mind is the GFCI equipment in the box is adjustable and can be adjusted to prevent false trip. On the other hand, GFCI breakers are not adjustable and may cause unnecessary trips.
I just realized you DO NOT have a CR4395 AC current sensing relay as the opening post stated, I think it’s a different device, a CR7310. Therefore at this point I have to consider that all my previous research is potentially invalid and not applicable. I do not have time to look into this issue any further.