Charge Point Home Flex Questions
05-08-2022, 09:02 AM
#1
Super Member
Thread Starter
Charge Point Home Flex Questions
I’ve two got 6/3 NM-B runs from a 50A breaker to two separate 14-50 outlets. My plan is to plug in Chargepoint for 40A charging of the EQS suv.
my question is related to the wiring -
Chargepoint supports hardwiring of this unit for 48 or 50 A charging. The unit supports wiring up to 6 gauge but no larger.
my understanding Is that the 6/3 I have may be insufficient for 48 or 50 amp charging despite it having an allowable ampacity of 55 amps (wire needs to follow 80% rule - if 55 amp rating in wire, can only support 44 amps continuous).
not applicable now, to this vehicle, but wondering how people are hardwiring the flex so that it pushes out 48 or 50
my question is related to the wiring -
Chargepoint supports hardwiring of this unit for 48 or 50 A charging. The unit supports wiring up to 6 gauge but no larger.
my understanding Is that the 6/3 I have may be insufficient for 48 or 50 amp charging despite it having an allowable ampacity of 55 amps (wire needs to follow 80% rule - if 55 amp rating in wire, can only support 44 amps continuous).
not applicable now, to this vehicle, but wondering how people are hardwiring the flex so that it pushes out 48 or 50
Last edited by bonboon; 05-09-2022 at 05:33 AM.
05-08-2022, 09:54 AM
#3
Super Member
Thread Starter
Questions mostly boil down to 1) what is max amperage 6-3 can support provided I have right breaker installed (I think 44) and 2) how are others hardwiring the flex if at all?
Question 1 boils down to: Is actual wire subject to 80% rule? In other words, does it need to be rated for 125% of expected continuous draw? (So in case of 50amp continuous draw, does wire need to be rated 62.5 or higher). Wire, not breaker, to be clear
Last edited by bonboon; 05-20-2022 at 09:15 AM.
06-01-2022, 04:19 PM
#4
I always recommend hardwiring the HomeFlex for 2 reasons. 1. If you want to future proof and be able to get the full 50A someday then you must hardwire. 2. Some municipalities require a GFCI CB for all outlets in a garage (including the NEMA14-50 outlet for your HomeFlex). The problem with a GFCI CB is that the HomeFlex already has GFCI built into the unit so when you have a GFCI CB in your panel combined with the GFCI built into the HomeFlex, it creates issues where the HomeFlex will stop charging because 2 GFCIs in the same circuit causes conflicts. If you hardwire, then electrical code won’t require a GFCI CB in your panel and the built in GFCI in the HomeFlex will operate without issue.
As far as the wire size, the largest wire size that can fit in the HomeFlex terminals is 6 AWG and the conduit connection is 3/4 inch. In order for 6 AWG wire to carry 50 continuous amps you need to use THHN wire rated for 90 degrees C or higher. Home Depot and Lowes carry it for sale by the foot. Do NOT use 6 AWG NM (Romex) wire as it is not able to carry 50 continuous amps. 6 AWG 90C THNN wire can safely carry 75 amps and must be enclosed in conduit. 75 amps wire would allow a continuous load of 60 amps which is more than the HomeFlex will ever pull (max it will pull is 50 amps) So the extra 10 amps can account for losses over longer runs and provide a safety factor. The other part of the electric code addresses how many wires you can stuff in conduit of a particular size and still have sufficient cooling for the wires. Occupancy of 3/4 Sch-80 PVC is limited to 35% to allow sufficient cooling. Cross sectional volume of 2x 6AWG (load wires ) + 1x 8AWG (ground) come to 32.5% which is less than the 35% max. The ground wire does not have to be 6 AWG since it is not carrying the continuous load. In summary, if you want to be extra safe and future proof your installation, use 6 AWG 90C THNN wire for you 2 load wires and 8 AWG copper wire for the ground wire. Enclose them in 3/4 inch conduit and use a 60 or 70 amp breaker. If you use 60 amp breaker then the maximum continuous load will be limited to 48 amps but you have a larger margin between the capacity of the wire and your breaker. In other words a 60 amp breaker will trip before the wire gets near its max capacity of 75 amps. Whereas a 70 amp breaker won’t trip until the load is much closer to the max of the wire. I used a 60 amp breaker for that reason but code allows you to use a 70 amp breaker if you want the full 50 amps from the HomeFlex. Of course the EQS max charging rate from an AC charger is 40 amps (9.6 KW) so hardwired this way is overkill but will future proof you and doesn’t add much to the cost of installation. My disclaimer is don’t do it yourself. Have a certified electrician do your installation and make sure he pulls a permit so your local authorities can inspect it.
As far as the wire size, the largest wire size that can fit in the HomeFlex terminals is 6 AWG and the conduit connection is 3/4 inch. In order for 6 AWG wire to carry 50 continuous amps you need to use THHN wire rated for 90 degrees C or higher. Home Depot and Lowes carry it for sale by the foot. Do NOT use 6 AWG NM (Romex) wire as it is not able to carry 50 continuous amps. 6 AWG 90C THNN wire can safely carry 75 amps and must be enclosed in conduit. 75 amps wire would allow a continuous load of 60 amps which is more than the HomeFlex will ever pull (max it will pull is 50 amps) So the extra 10 amps can account for losses over longer runs and provide a safety factor. The other part of the electric code addresses how many wires you can stuff in conduit of a particular size and still have sufficient cooling for the wires. Occupancy of 3/4 Sch-80 PVC is limited to 35% to allow sufficient cooling. Cross sectional volume of 2x 6AWG (load wires ) + 1x 8AWG (ground) come to 32.5% which is less than the 35% max. The ground wire does not have to be 6 AWG since it is not carrying the continuous load. In summary, if you want to be extra safe and future proof your installation, use 6 AWG 90C THNN wire for you 2 load wires and 8 AWG copper wire for the ground wire. Enclose them in 3/4 inch conduit and use a 60 or 70 amp breaker. If you use 60 amp breaker then the maximum continuous load will be limited to 48 amps but you have a larger margin between the capacity of the wire and your breaker. In other words a 60 amp breaker will trip before the wire gets near its max capacity of 75 amps. Whereas a 70 amp breaker won’t trip until the load is much closer to the max of the wire. I used a 60 amp breaker for that reason but code allows you to use a 70 amp breaker if you want the full 50 amps from the HomeFlex. Of course the EQS max charging rate from an AC charger is 40 amps (9.6 KW) so hardwired this way is overkill but will future proof you and doesn’t add much to the cost of installation. My disclaimer is don’t do it yourself. Have a certified electrician do your installation and make sure he pulls a permit so your local authorities can inspect it.
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bonboon (06-01-2022)
06-01-2022, 04:24 PM
#5
Super Member
Thread Starter
I always recommend hardwiring the HomeFlex for 2 reasons. 1. If you want to future proof and be able to get the full 50A someday then you must hardwire. 2. Some municipalities require a GFCI CB for all outlets in a garage (including the NEMA14-50 outlet for your HomeFlex). The problem with a GFCI CB is that the HomeFlex already has GFCI built into the unit so when you have a GFCI CB in your panel combined with the GFCI built into the HomeFlex, it creates issues where the HomeFlex will stop charging because 2 GFCIs in the same circuit causes conflicts. If you hardwire, then electrical code won’t require a GFCI CB in your panel and the built in GFCI in the HomeFlex will operate without issue.
As far as the wire size, the largest wire size that can fit in the HomeFlex terminals is 6 AWG and the conduit connection is 3/4 inch. In order for 6 AWG wire to carry 50 continuous amps you need to use THHN wire rated for 90 degrees C or higher. Home Depot and Lowes carry it for sale by the foot. Do NOT use 6 AWG NM (Romex) wire as it is not able to carry 50 continuous amps. 6 AWG 90C THNN wire can safely carry 75 amps and must be enclosed in conduit. 75 amps wire would allow a continuous load of 60 amps which is more than the HomeFlex will ever pull (max it will pull is 50 amps) So the extra 10 amps can account for losses over longer runs and provide a safety factor. The other part of the electric code addresses how many wires you can stuff in conduit of a particular size and still have sufficient cooling for the wires. Occupancy of 3/4 Sch-80 PVC is limited to 35% to allow sufficient cooling. Cross sectional volume of 2x 6AWG (load wires ) + 1x 8AWG (ground) come to 32.5% which is less than the 35% max. The ground wire does not have to be 6 AWG since it is not carrying the continuous load. In summary, if you want to be extra safe and future proof your installation, use 6 AWG 90C THNN wire for you 2 load wires and 8 AWG copper wire for the ground wire. Enclose them in 3/4 inch conduit and use a 60 or 70 amp breaker. If you use 60 amp breaker then the maximum continuous load will be limited to 48 amps but you have a larger margin between the capacity of the wire and your breaker. In other words a 60 amp breaker will trip before the wire gets near its max capacity of 75 amps. Whereas a 70 amp breaker won’t trip until the load is much closer to the max of the wire. I used a 60 amp breaker for that reason but code allows you to use a 70 amp breaker if you want the full 50 amps from the HomeFlex. Of course the EQS max charging rate from an AC charger is 40 amps (9.6 KW) so hardwired this way is overkill but will future proof you and doesn’t add much to the cost of installation. My disclaimer is don’t do it yourself. Have a certified electrician do your installation and make sure he pulls a permit so your local authorities can inspect it.
As far as the wire size, the largest wire size that can fit in the HomeFlex terminals is 6 AWG and the conduit connection is 3/4 inch. In order for 6 AWG wire to carry 50 continuous amps you need to use THHN wire rated for 90 degrees C or higher. Home Depot and Lowes carry it for sale by the foot. Do NOT use 6 AWG NM (Romex) wire as it is not able to carry 50 continuous amps. 6 AWG 90C THNN wire can safely carry 75 amps and must be enclosed in conduit. 75 amps wire would allow a continuous load of 60 amps which is more than the HomeFlex will ever pull (max it will pull is 50 amps) So the extra 10 amps can account for losses over longer runs and provide a safety factor. The other part of the electric code addresses how many wires you can stuff in conduit of a particular size and still have sufficient cooling for the wires. Occupancy of 3/4 Sch-80 PVC is limited to 35% to allow sufficient cooling. Cross sectional volume of 2x 6AWG (load wires ) + 1x 8AWG (ground) come to 32.5% which is less than the 35% max. The ground wire does not have to be 6 AWG since it is not carrying the continuous load. In summary, if you want to be extra safe and future proof your installation, use 6 AWG 90C THNN wire for you 2 load wires and 8 AWG copper wire for the ground wire. Enclose them in 3/4 inch conduit and use a 60 or 70 amp breaker. If you use 60 amp breaker then the maximum continuous load will be limited to 48 amps but you have a larger margin between the capacity of the wire and your breaker. In other words a 60 amp breaker will trip before the wire gets near its max capacity of 75 amps. Whereas a 70 amp breaker won’t trip until the load is much closer to the max of the wire. I used a 60 amp breaker for that reason but code allows you to use a 70 amp breaker if you want the full 50 amps from the HomeFlex. Of course the EQS max charging rate from an AC charger is 40 amps (9.6 KW) so hardwired this way is overkill but will future proof you and doesn’t add much to the cost of installation. My disclaimer is don’t do it yourself. Have a certified electrician do your installation and make sure he pulls a permit so your local authorities can inspect it.
